JP7473157B2 - Anchoring support method and anchoring support system - Google Patents
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- JP7473157B2 JP7473157B2 JP2020019077A JP2020019077A JP7473157B2 JP 7473157 B2 JP7473157 B2 JP 7473157B2 JP 2020019077 A JP2020019077 A JP 2020019077A JP 2020019077 A JP2020019077 A JP 2020019077A JP 7473157 B2 JP7473157 B2 JP 7473157B2
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- 238000004873 anchoring Methods 0.000 title claims description 53
- 238000000034 method Methods 0.000 title claims description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 49
- 238000005259 measurement Methods 0.000 claims description 22
- 230000000694 effects Effects 0.000 claims description 17
- 239000002689 soil Substances 0.000 claims description 15
- 238000009795 derivation Methods 0.000 claims description 11
- 238000013459 approach Methods 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 16
- 230000007423 decrease Effects 0.000 description 9
- 230000000630 rising effect Effects 0.000 description 8
- 238000004364 calculation method Methods 0.000 description 6
- 238000011160 research Methods 0.000 description 6
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000001141 propulsive effect Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 230000005856 abnormality Effects 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
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Description
本発明は、錨と錨鎖を有した船舶の錨泊を支援する錨泊支援方法及び錨泊支援システムに関する。 The present invention relates to an anchoring support method and an anchoring support system that support anchoring of a ship equipped with an anchor and anchor chain.
走錨とは、錨泊中の船舶が錨と錨鎖の把駐力（船舶をつなぎ止める力）を超えた外力を風や波などから受けたときに船舶が錨と錨鎖を引きずりながら外力の方向に押し流される現象のことをいう。いったん走錨が始まると船舶を止めることは困難で、これまでにもしばしば衝突や座礁などの重大な海難事故を引き起こす原因となってきた。
走錨を検知するための主な研究例としては、強風下における船舶の振れ回り運動などをＧＰＳやレーダー等によって監視して、その異常を発見することによって走錨をいち早く検知しようとする方法がある（研究例ａ）。また、研究例ａに関連する方法として、ＧＰＳ等で錨と船舶の位置を比較し、これらの距離と錨鎖の長さから走錨を検知しようとする方法がある（研究例ｂ）。また、何らかの方法で計測又は評価した錨鎖に働く張力を、別途推定した錨と錨鎖の形状から決まる静的最大把駐力と比較して、前者が後者を超えたら走錨が発生するとしてこれを検知しようとする方法がある（研究例ｃ）。研究例ｃの方法は、力の理論値と計測値等の比較による方法なので、走錨に至るまでの余裕の程度（危険余裕）を知ることができる点で有用と考えられる。
Anchor dragging is a phenomenon in which a ship at anchor is pushed in the direction of the external force, dragging the anchor and anchor chain, when the ship receives external forces from wind or waves that exceed the holding power of the anchor and anchor chain (the power that holds the ship in place). Once an anchor dragging begins, it is difficult to stop the ship, and in the past it has often been the cause of serious marine accidents such as collisions and groundings.
The main research examples for detecting dragging anchor include a method that monitors the swaying movement of a ship in strong winds using GPS or radar, and detects the dragging anchor as early as possible by finding the abnormality (Research example a). Another method related to Research example a is a method that compares the position of the anchor and the ship using GPS, etc., and detects the dragging anchor from the distance between them and the length of the anchor chain (Research example b). Another method compares the tension acting on the anchor chain, measured or evaluated in some way, with the static maximum holding force determined from the anchor and anchor chain shapes estimated separately, and detects the occurrence of the dragging anchor if the former exceeds the latter (Research example c). The method of Research example c is a method that compares the theoretical value of the force with the measured value, etc., and is therefore considered useful in that it can tell the degree of margin (risk margin) before the anchor drags.
また、特許文献１には、海底土質検出器と、繰出し描鎖長検出器と、錨鎖角検出器と、錨鎖張力検出器と、風向風速検出器と、潮流検出器と、これらの検出器からの検出信号を受けて錨と錨鎖との最大把駐力および船体に働く外力を演算すると共に錨鎖張力を最大把駐力以下に保持するのに必要な縦横方向の守錨制御推進力を演算し、守錨制御推進力に応じた制御信号を主機制御手段、旋回装置制御手段或いは吃水制御手段へ出力する制御装置とを備えた自動守錨制御装置が開示されている。
また、特許文献２には、自船から錨に至る水平距離を、錨鎖張力と水深とを用いて錨鎖カテナリ理論式で求めた錨鎖カテナリと繰出し錨鎖長とから演算し、投錨位置から現在の自船位置に至る水平距離を、自船の船速若しくは加速度を投錨から現在に亙って時間積分することにより演算し、自船から錨に至る水平距離と投錨位置から現在の自船位置に至る水平距離とを比較することにより走錨を検知する走錨検知方法が開示されている。
また、特許文献３には、チェーンの張力を計測する張力測定装置と、測定値を送信する送信器と、船体側に備えられ送信器からの信号を受信する受信器とを有する錨の把駐力測定装置が開示されている。
Patent Document 1 also discloses an automatic anchorage control device that includes a seabed soil detector, a payout chain length detector, an anchor chain angle detector, an anchor chain tension detector, a wind direction and speed detector, a tidal current detector, and a control device that receives detection signals from these detectors to calculate the maximum holding force of the anchor and anchor chain and the external forces acting on the hull, as well as calculates the anchorage control propulsive forces in the longitudinal and lateral directions necessary to keep the anchor chain tension below the maximum holding force, and outputs control signals according to the anchorage control propulsive forces to a main engine control means, a turning gear control means or a draft control means.
Patent Document 2 also discloses a method of detecting anchor dragging in which the horizontal distance from the ship to the anchor is calculated from the anchor chain catenary calculated using the anchor chain catenary theoretical formula based on the anchor chain tension and water depth, and the length of the let-out anchor chain, and the horizontal distance from the anchor drop position to the ship's current position is calculated by integrating the ship's speed or acceleration over time from the anchor drop to the present, and a method of detecting anchor dragging is disclosed in which the horizontal distance from the ship to the anchor is calculated from the anchor chain catenary theoretical formula using the anchor chain tension and water depth, and the horizontal distance from the anchor drop position to the ship's current position is calculated by comparing the horizontal distance from the ship to the anchor with the horizontal distance from the anchor drop position to the ship's current position.
Furthermore, Patent Document 3 discloses an anchor holding force measuring device that has a tension measuring device that measures the tension of a chain, a transmitter that transmits the measured value, and a receiver that is provided on the hull side and receives a signal from the transmitter.
研究例ａの方法では、走錨が発生した段階でこれをいち早く検知することには役立っても、走錨に至るまでの危険性を前もって評価する手段とはなりにくい。また研究例ｂの方法においては、海底土質や錨と錨鎖の性能も考慮されず、錨と船舶の距離がどれくらいになったら走錨に至るかの裏付けが十分とはいえない。
研究例ｃの方法に関するこれまでの研究は、海底土質や錨と錨鎖の性能を考慮しているものの、錨と錨鎖の形状から決まる静的最大把駐力は外力の大きさによって変化するので比較すべき値としては必ずしも適当とはいえない。また、研究例ｃの方法では、錨鎖の一部が海底にある場合を主に対象としてきており、錨鎖のすべてが懸垂曲線を描くような状況を対象とした研究は少ない。錨鎖のすべてが懸垂曲線を描くような状況では錨鎖が錨を斜め上方に引くことになるため錨の把駐力が減少することが知られているが、この効果を考慮した研究も少ない。また、これらを考慮した研究においては、海底から錨鎖が立ち上がる角度と錨の把駐力の関係を用いるため繰り返し計算を必要としており、限界把駐力が陽に求められないほか、どういう条件で錨鎖のすべてが懸垂曲線を描くかの検討も十分とはいえない。
While the method in Study A is useful for quickly detecting anchor dragging when it occurs, it is difficult to use it as a means of evaluating the risk of anchor dragging in advance. Furthermore, the method in Study B does not take into account the seabed soil quality or the performance of the anchor and anchor chain, and it cannot be said that there is sufficient evidence that the distance between the anchor and the ship must be at before anchor dragging occurs.
Previous studies on the method of Study Example C have taken into account the seabed soil quality and the performance of the anchor and anchor chain, but the static maximum holding force determined by the shape of the anchor and anchor chain changes depending on the magnitude of the external force, so it is not necessarily an appropriate value to compare. In addition, the method of Study Example C has mainly focused on cases where part of the anchor chain is on the seabed, and there have been few studies that have looked at situations where the entire anchor chain forms a catenary curve. It is known that the holding force of the anchor decreases when the entire anchor chain forms a catenary curve because the anchor chain pulls the anchor diagonally upward, but there are few studies that take this effect into account. In addition, studies that take these factors into account require repeated calculations to use the relationship between the angle at which the anchor chain rises from the seabed and the holding force of the anchor, so the ultimate holding force cannot be obtained explicitly, and the conditions under which the entire anchor chain forms a catenary curve are not fully examined.
また、特許文献１は、錨自体の把駐力に錨鎖の把駐力を加えたものを最大把駐力とするものであるが、錨鎖の把駐力を決めるにあたっては錨鎖の海底直線部長さと錨鎖単位重量のみを考慮しており、海底における錨鎖の立ち上がり状況は考慮していない。よって、最大把駐力（限界把駐力）を精度よく把握できているとはいい難い。
また、特許文献２は、船舶の現在位置と投錨位置とのなす距離を錨鎖張力等から推定した錨までの距離と比較して走錨を検知しようとするものであるから、走錨が発生したことを早期に検知することはできても、走錨の危険性を事前に評価することは困難である。
また、特許文献３は、実際の把駐力を計測することを主眼においており、理論把駐力については、形状や重量等に基づいて計算により求めることができる程度の記載しかない。よって、理論把駐力（限界把駐力）を精度よく把握できているとはいい難い。
In addition, in Patent Document 1, the maximum holding force is the sum of the holding force of the anchor itself and the holding force of the anchor chain, but when determining the holding force of the anchor chain, only the straight length of the anchor chain on the seabed and the unit weight of the anchor chain are taken into consideration, and the rising state of the anchor chain on the seabed is not taken into consideration. Therefore, it is difficult to say that the maximum holding force (limit holding force) is accurately grasped.
In addition, Patent Document 2 attempts to detect anchor dragging by comparing the distance between the ship's current position and the anchor position with the distance to the anchor estimated from the anchor chain tension, etc., so while it is possible to detect anchor dragging at an early stage, it is difficult to assess the risk of anchor dragging in advance.
In addition, Patent Document 3 focuses on measuring the actual holding force, and only describes the theoretical holding force to the extent that it can be calculated based on the shape, weight, etc. Therefore, it is difficult to say that the theoretical holding force (limit holding force) is accurately understood.
そこで本発明は、限界把駐力を精度よく導出して走錨の危険性を的確に評価する錨泊支援方法及び錨泊支援システムを提供することを目的とする。 The present invention aims to provide an anchoring support method and system that accurately derives the limiting holding force and accurately evaluates the risk of anchor dragging.
請求項１記載に対応した錨泊支援方法においては、錨と錨鎖を有した船舶の錨泊を支援する方法であって、錨鎖の伸出錨鎖長さにより異なる限界把駐力と、錨鎖にかかる錨鎖水平張力とを比較して、走錨の危険性を評価するに当り、限界把駐力を、少なくとも錨の水中重量と、錨の性能と水底土質により決められる錨の把駐力係数、及び錨鎖の水底への横たわり状態を考慮して導出するものであり、限界把駐力を、伸出錨鎖長さに基づいた式（１）及び式（２）で決まる、錨鎖の一部が水底に横たわった状態である第一の状態、錨鎖が水底に横たわっておらず水底から角度０で立ち上がった状態である第二の状態、錨鎖が水底に横たわっておらず水底から０度より大きい角度で立ち上がった状態である第三の状態の３つの状態に分けて導出することを特徴とする。
ｋ
ｃ
：状態分岐錨鎖長さ（ｍ）
ｈ ：水底の錨から錨鎖口までの高さ（ｍ）
ｒ
ａ
：錨の把駐力係数
ｗ
ａ
：錨の水中重量（Ｎ）
ｗ
ｃ
：錨鎖の単位長さ当たり水中重量（Ｎ/ｍ）
請求項１に記載の本発明によれば、錨鎖の伸出錨鎖長さを考慮した精度の高い限界把駐力と、錨鎖水平張力とを用いて走錨の危険性を的確に評価することができる。また、限界把駐力を精度よく導出することができる。なお、さらに錨鎖張力の上向き成分が錨の把駐力におよぼす影響を考慮してもよい。また、第一から第三の状態の内どの状態で限界把駐力が現れるかを判断してその状態における限界把駐力を導出するため、限界把駐力をさらに精度よく導出することができる。
The anchoring support method according to claim 1 is a method for supporting anchoring of a ship having an anchor and anchor chain, and when evaluating the risk of anchor dragging by comparing the limiting holding force, which differs depending on the extended anchor chain length, with the horizontal tension of the anchor chain applied to the anchor chain, the limiting holding force is derived taking into consideration at least the underwater weight of the anchor, the holding force coefficient of the anchor, which is determined by the performance of the anchor and the soil quality of the bottom of the water, and the state of the anchor chain lying on the bottom of the water , and is characterized in that the limiting holding force is derived in three states, determined by formulas (1) and (2) based on the extended anchor chain length: a first state in which a part of the anchor chain is lying on the bottom of the water, a second state in which the anchor chain is not lying on the bottom of the water and is raised from the bottom at an angle of 0 degrees, and a third state in which the anchor chain is not lying on the bottom of the water and is raised from the bottom at an angle greater than 0 degrees .
kc : State branch anchor chain length (m)
h: Height from the anchor on the bottom of the water to the anchor chain opening (m)
r a : Anchor holding power coefficient
wa : Underwater weight of anchor (N)
wc : Underwater weight per unit length of anchor chain (N/m )
According to the present invention as set forth in claim 1, the risk of anchor dragging can be accurately evaluated using a highly accurate limiting holding force that takes into account the extended length of the anchor chain and the horizontal tension of the anchor chain. The limiting holding force can also be derived with high accuracy. The effect of the upward component of the anchor chain tension on the anchor's holding force may also be taken into account. Furthermore, the limiting holding force can be derived with even higher accuracy by determining in which of the first to third states the limiting holding force appears and deriving the limiting holding force in that state.
請求項２記載の本発明は、３つの状態ごとに限界把駐力（Ｔｈ
＊）を、第一の状態は式(３)、第二の状態は式(４)、第三の状態は式(５)から式（８）に基づいて導出することを特徴とする。
ｈ ：水底の錨から錨鎖口までの高さ(ｍ)
ｒａ：錨の把駐力係数
ｗａ：錨の水中重量(Ｎ)
ｒｃ：錨鎖の把駐力係数
ｗｃ：錨鎖の単位長さ当たり水中重量(Ｎ/ｍ)
ｋ ：伸出錨鎖長さ(ｍ)
α ：錨鎖張力の上向き成分が錨の把駐力におよぼす影響を表す係数
請求項２に記載の本発明によれば、各状態における限界把駐力を精度よく導出することができる。
The present invention as described in claim 2 is characterized in that the limit holding force (T h * ) is derived for each of the three states based on equation (3) for the first state, equation (4) for the second state, and equations (5) to (8) for the third state.
ra : Holding power coefficient of anchor wa : Underwater weight of anchor (N)
r c : Holding power coefficient of anchor cable w c : Underwater weight per unit length of anchor cable (N/m)
k: Length of extended anchor chain (m)
α: Coefficient expressing the effect of the upward component of the anchor cable tension on the holding force of the anchor. According to the present invention described in claim 2 , the limit holding force in each state can be accurately derived.
請求項３記載の本発明は、錨鎖水平張力を、錨鎖にかかる張力を計測した結果に基づいて求めることを特徴とする。
請求項３に記載の本発明によれば、張力の計測結果に基づいて錨鎖水平張力を精度よく求めることができる。
The present invention as defined in claim 3 is characterized in that the horizontal tension of the anchor chain is determined based on the result of measuring the tension applied to the anchor chain.
According to the present invention as defined in claim 3 , the horizontal tension of the anchor chain can be determined with high accuracy based on the tension measurement results.
請求項４記載の本発明は、錨鎖水平張力を、錨鎖口における錨鎖の錨鎖鉛直（上下）角度、錨鎖の空中長さ、及び錨鎖の空中部分の水平長さの少なくともいずれか１つを用いて推定することを特徴とする。
請求項４に記載の本発明によれば、錨鎖の状態から錨鎖水平張力を精度よく推定することができる。
The present invention as set forth in claim 4 is characterized in that the horizontal tension of the anchor chain is estimated using at least one of the vertical (up and down) angle of the anchor chain at the anchor chain mouth, the length of the anchor chain in the air, and the horizontal length of the part of the anchor chain in the air.
According to the present invention as defined in claim 4 , the horizontal tension of the anchor chain can be estimated with high accuracy from the state of the anchor chain.
請求項５記載の本発明は、限界把駐力と錨鎖水平張力との比較を、限界把駐力時における錨鎖鉛直（上下）角度と現在の錨鎖鉛直（上下）角度、限界把駐力時における空中長さと現在の空中長さ、及び限界把駐力時における空中部分の水平長さと現在の空中部分の水平長さの少なくともいずれか１つを比較して行うことを特徴とする。
請求項５に記載の本発明によれば、走錨の危険性を、限界把駐力時と現在の錨鎖鉛直（上下）角度、錨鎖の空中長さ、又は錨鎖の空中部分の水平長さを用いて評価することができる。
The present invention as described in claim 5 is characterized in that the comparison between the limit holding force and the horizontal tension of the anchor chain is made by comparing at least one of the anchor chain vertical (up and down) angle at the limit holding force and the current anchor chain vertical (up and down) angle, the aerial length at the limit holding force and the current aerial length, and the horizontal length of the aerial portion at the limit holding force and the current horizontal length of the aerial portion.
According to the present invention as set forth in claim 5 , the risk of anchor dragging can be evaluated using the vertical (up and down) angle of the anchor chain at the time of maximum holding force and the current time, the length of the anchor chain in the air, or the horizontal length of the part of the anchor chain in the air.
請求項６記載の本発明は、限界把駐力と錨鎖水平張力を時系列的に表示することを特徴とする。
請求項６に記載の本発明によれば、船長等は、錨鎖水平張力が刻々変化することによる限界把駐力と錨鎖水平張力との差分の増減傾向を把握しやすくなるため、走錨の危険性を把握して走錨を防ぐための対応をより的確に行うことができる。
The present invention as set forth in claim 6 is characterized in that the limit holding force and the horizontal tension of the anchor cable are displayed in chronological order.
According to the present invention described in claim 6 , the captain, etc. can easily grasp the increasing/decreasing trend of the difference between the limit holding force and the horizontal anchor chain tension due to the moment-to-moment change in the horizontal anchor chain tension, so that he or she can grasp the risk of anchor dragging and take more appropriate measures to prevent it.
請求項７記載の本発明は、限界把駐力と錨鎖水平張力の差分を表示又は差分に基づいて警報することを特徴とする。
請求項７に記載の本発明によれば、差分を表示することで船長等に走錨の危険性をより正確に知らせることができる。また差分に基づいて警報することで船長等に走錨を防ぐための対応を促すことができる。
The present invention as set forth in claim 7 is characterized in that the difference between the limit holding force and the horizontal tension of the anchor chain is displayed or an alarm is given based on the difference.
According to the seventh aspect of the present invention, by displaying the difference, it is possible to more accurately inform the captain or the like of the risk of anchor dragging. Also, by issuing an alarm based on the difference, it is possible to encourage the captain or the like to take measures to prevent anchor dragging.
請求項８記載に対応した錨泊支援システムにおいては、錨と錨鎖を有した船舶の錨泊を支援するシステムであって、錨鎖の伸出錨鎖長さにより異なる限界把駐力を導出する限界把駐力導出手段と、錨鎖にかかる錨鎖水平張力を導出する錨鎖水平張力導出手段と、限界把駐力と錨鎖水平張力とを比較して走錨の危険性を推定する走錨危険性推定手段とを備え、限界把駐力導出手段が、限界把駐力を、錨泊支援方法に基づいて導出することを特徴とする。
請求項８に記載の本発明によれば、錨鎖の伸出錨鎖長さを考慮した精度の高い限界把駐力と、錨鎖水平張力とを用いて走錨の危険性を的確に評価することができる。また、限界把駐力を精度よく導出することができる。
The anchoring support system according to claim 8 is a system for supporting anchoring of a ship having an anchor and anchor chain, and is provided with a limit holding force deriving means for deriving a limit holding force which differs depending on the extended length of the anchor chain, an anchor chain horizontal tension deriving means for deriving the horizontal tension of the anchor chain on the anchor chain, and an anchor dragging risk estimating means for estimating the risk of anchor dragging by comparing the limit holding force with the horizontal anchor chain tension, and is characterized in that the limit holding force deriving means derives the limit holding force based on the anchoring support method.
According to the present invention as set forth in claim 8 , the risk of anchor dragging can be accurately evaluated using the highly accurate limit holding force that takes into account the extended length of the anchor chain and the horizontal tension of the anchor chain. Also, the limit holding force can be derived with high accuracy.
請求項９記載の本発明は、錨鎖水平張力導出手段が、錨鎖の張力を検出する張力計測手段の計測結果に基づいて錨鎖水平張力を導出することを特徴とする。
請求項９に記載の本発明によれば、張力の計測結果に基づいて錨鎖水平張力を精度よく導出することができる。
The present invention as recited in claim 9 is characterized in that the anchor chain horizontal tension deriving means derives the anchor chain horizontal tension based on a measurement result of a tension measuring means which detects the tension of the anchor chain.
According to the present invention as defined in claim 9 , the horizontal tension of the anchor chain can be derived with high accuracy based on the tension measurement results.
請求項１０記載の本発明は、錨鎖水平張力導出手段が、錨鎖口における錨鎖の錨鎖鉛直（上下）角度を計測する錨鎖角度計測手段、錨鎖の空中長さを計測する空中長計測手段、及び錨鎖の空中部分の水平長さを計測する水平長計測手段の少なくともいずれか１つの計測結果に基づいて錨鎖水平張力を導出することを特徴とする。
請求項１０に記載の本発明によれば、錨鎖の状態から錨鎖水平張力を精度よく導出することができる。
The present invention as defined in claim 10 is characterized in that the anchor chain horizontal tension deriving means derives the horizontal anchor chain tension based on at least one measurement result of anchor chain angle measuring means which measures the vertical (up and down) angle of the anchor chain at the anchor chain mouth, aerial length measuring means which measures the aerial length of the anchor chain, and a horizontal length measuring means which measures the horizontal length of the aerial portion of the anchor chain.
According to the present invention as defined in claim 10 , the horizontal tension of the anchor chain can be derived with high accuracy from the state of the anchor chain.
請求項１１記載の本発明は、錨泊支援を行う報知手段をさらに備え、走錨危険性推定手段の推定結果を報知手段を用いて報知することを特徴とする。
請求項１１に記載の本発明によれば、船長等に走錨の危険性の推定結果を提供することができる。
The present invention as defined in claim 11 is characterized in that it further comprises an informing means for performing anchoring support, and the informing means is used to inform of the result of estimation by the anchor dragging risk estimating means.
According to the present invention as defined in claim 11 , it is possible to provide the captain or the like with an estimated result of the risk of anchor dragging.
請求項１２記載の本発明は、報知手段として表示手段を用い、限界把駐力導出手段で導出された限界把駐力と、錨鎖水平張力導出手段で導出された錨鎖水平張力を時系列的に表示し、走錨の危険性を限界把駐力と錨鎖水平張力の差分として表示することを特徴とする。
請求項１２に記載の本発明によれば、船長等は、錨鎖水平張力が刻々変化することによる限界把駐力と錨鎖水平張力との差分の増減傾向を時系列的に表示された限界把駐力と錨鎖水平張力から把握しやすくなり、また表示された差分により走錨の危険性を正確に把握しやすくなるため、走錨を防ぐための対応をより的確に行うことができる。
The present invention as described in claim 12 is characterized in that a display means is used as the notification means, and the limit holding force derived by the limit holding force derivation means and the horizontal anchor chain tension derived by the horizontal anchor chain tension derivation means are displayed in chronological order, and the risk of anchor dragging is displayed as the difference between the limit holding force and the horizontal anchor chain tension.
According to the present invention as described in claim 12 , the captain, etc. can easily grasp the increasing or decreasing trend of the difference between the limit holding force and the horizontal anchor chain tension due to moment-to-moment changes in the horizontal anchor chain tension from the limit holding force and horizontal anchor chain tension displayed in chronological order, and the displayed difference makes it easier to accurately grasp the risk of anchor dragging, so that measures to prevent anchor dragging can be taken more appropriately.
請求項１３記載の本発明は、差分に閾値を設け、走錨の危険性が所定の閾値以下になった場合、または差分の閾値に近づく速度を判断して、警報をして報知することを特徴とする。
請求項１３に記載の本発明によれば、警報により船長等に走錨を防ぐための対応を的確に促すことができる。特に、差分の閾値に近づく速度を判断して警報する場合は、走錨の危険性の状況変化に対応して緊急に報知することができる。
The present invention as described in claim 13 is characterized in that a threshold value is set for the difference, and when the risk of anchor dragging falls below a predetermined threshold value, or when the speed of the difference approaches the threshold value, an alarm is sounded to notify the driver.
According to the present invention as set forth in claim 13 , the alarm can appropriately prompt the captain or the like to take measures to prevent anchor dragging. In particular, when the alarm is issued based on the speed approaching the difference threshold, it is possible to notify the captain or the like urgently in response to a change in the situation of the risk of anchor dragging.
本発明の錨泊支援方法によれば、錨鎖の伸出錨鎖長さを考慮した精度の高い限界把駐力と、錨鎖水平張力とを用いて走錨の危険性を的確に評価することができる。また、限界把駐力を精度よく導出することができる。なお、さらに錨鎖張力の上向き成分が錨の把駐力におよぼす影響を考慮してもよい。 According to the anchoring support method of the present invention, the risk of anchor dragging can be accurately evaluated using a highly accurate limiting holding force that takes into account the extended length of the anchor chain and the horizontal tension of the anchor chain. In addition, the limiting holding force can be derived with high accuracy. Furthermore, the effect of the upward component of the anchor chain tension on the holding force of the anchor can be further taken into account.
また、限界把駐力を、伸出錨鎖長さに基づいた式（１）及び式（２）で決まる、錨鎖の一部が水底に横たわった状態である第一の状態、錨鎖が水底に横たわっておらず水底から角度０で立ち上がった状態である第二の状態、錨鎖が水底に横たわっておらず水底から０度より大きい角度で立ち上がった状態である第三の状態の３つの状態に分けて導出するので、第一から第三の状態の内どの状態で限界把駐力が現れるかを判断してその状態における限界把駐力を導出するため、限界把駐力をさらに精度よく導出することができる。 In addition, the limit holding force is derived by dividing it into three states, which are determined by equations (1) and (2) based on the extended anchor chain length: a first state in which part of the anchor chain is lying on the bottom of the water; a second state in which the anchor chain is not lying on the bottom of the water but stands up from the bottom at an angle of 0 degrees; and a third state in which the anchor chain is not lying on the bottom of the water but stands up from the bottom at an angle of greater than 0 degrees. Therefore , it is possible to determine which state out of the first to third states the limit holding force appears in and derive the limit holding force in that state, thereby making it possible to derive the limit holding force with even greater accuracy.
また、３つの状態ごとに限界把駐力Ｔｈ ＊を、第一の状態は式(３)、第二の状態は式(４)、第三の状態は式(５)から式（８）に基づいて導出する場合は、各状態における限界把駐力を精度よく導出することができる。 Furthermore, if the limit holding force T h * is derived for each of the three states based on equation (3) for the first state, equation (4) for the second state, and equations (5) to (8) for the third state, the limit holding force in each state can be derived with high accuracy.
また、錨鎖水平張力を、錨鎖にかかる張力を計測した結果に基づいて求める場合は、張力の計測結果に基づいて錨鎖水平張力を精度よく求めることができる。 In addition, when the horizontal tension of the anchor chain is calculated based on the results of measuring the tension applied to the anchor chain, the horizontal tension of the anchor chain can be calculated with high accuracy based on the results of the tension measurement.
また、錨鎖水平張力を、錨鎖口における錨鎖の錨鎖鉛直（上下）角度、錨鎖の空中長さ、及び錨鎖の空中部分の水平長さの少なくともいずれか１つを用いて推定する場合は、錨鎖の状態から錨鎖水平張力を精度よく推定することができる。 In addition, if the horizontal tension of the anchor chain is estimated using at least one of the vertical (up and down) angle of the anchor chain at the anchor chain mouth, the length of the anchor chain in the air, and the horizontal length of the part of the anchor chain in the air, the horizontal tension of the anchor chain can be estimated with high accuracy from the condition of the anchor chain.
また、限界把駐力と錨鎖水平張力との比較を、限界把駐力時における錨鎖鉛直（上下）角度と現在の錨鎖鉛直（上下）角度、限界把駐力時における空中長さと現在の空中長さ、及び限界把駐力時における空中部分の水平長さと現在の空中部分の水平長さの少なくともいずれか１つを比較して行う場合は、走錨の危険性を、限界把駐力時と現在の錨鎖鉛直（上下）角度、錨鎖の空中長さ、又は錨鎖の空中部分の水平長さを用いて評価することができる。 In addition, if the comparison between the limit holding force and the horizontal tension of the anchor chain is made by comparing at least one of the vertical (up and down) angle of the anchor chain at the limit holding force and the current vertical (up and down) angle of the anchor chain, the aerial length at the limit holding force and the current aerial length, and the horizontal length of the aerial portion at the limit holding force and the current horizontal length of the aerial portion, the risk of anchor dragging can be evaluated using the vertical (up and down) angle of the anchor chain at the limit holding force and the current aerial length of the anchor chain, or the horizontal length of the aerial portion of the anchor chain.
また、限界把駐力と錨鎖水平張力を時系列的に表示する場合は、船長等は、錨鎖水平張力が刻々変化することによる限界把駐力と錨鎖水平張力との差分の増減傾向を把握しやすくなるため、走錨の危険性を把握して走錨を防ぐための対応をより的確に行うことができる。 In addition, if the maximum holding force and horizontal anchor chain tension are displayed over time, the captain and other personnel can easily grasp the increasing or decreasing trend in the difference between the maximum holding force and the horizontal anchor chain tension due to the moment-to-moment change in the horizontal anchor chain tension, and can therefore grasp the risk of anchor dragging and take more appropriate measures to prevent it.
また、限界把駐力と錨鎖水平張力の差分を表示又は差分に基づいて警報する場合は、差分を表示することで船長等に走錨の危険性をより正確に知らせることができる。また差分に基づいて警報することで船長等に走錨を防ぐための対応を促すことができる。 In addition, when the difference between the maximum holding force and the horizontal tension of the anchor chain is displayed or an alarm is issued based on the difference, the difference can be displayed to more accurately inform the captain and other personnel of the risk of anchor dragging. Furthermore, an alarm based on the difference can be issued to encourage the captain and other personnel to take measures to prevent anchor dragging.
また、本発明の錨泊支援システムによれば、錨鎖の伸出錨鎖長さを考慮した精度の高い限界把駐力と、錨鎖水平張力とを用いて走錨の危険性を的確に評価することができる。また、限界把駐力を精度よく導出することができる。 In addition, the anchoring support system of the present invention can accurately assess the risk of anchor dragging using a highly accurate limit holding force that takes into account the extended length of the anchor chain and the horizontal tension of the anchor chain. It can also accurately derive the limit holding force.
また、錨鎖水平張力導出手段が、錨鎖の張力を検出する張力計測手段の計測結果に基づいて錨鎖水平張力を導出する場合は、張力の計測結果に基づいて錨鎖水平張力を精度よく導出することができる。 In addition, when the anchor chain horizontal tension derivation means derives the anchor chain horizontal tension based on the measurement results of a tension measurement means that detects the tension of the anchor chain, the anchor chain horizontal tension can be derived with high accuracy based on the tension measurement results.
また、錨鎖水平張力導出手段が、錨鎖口における錨鎖の錨鎖鉛直（上下）角度を計測する錨鎖角度計測手段、錨鎖の空中長さを計測する空中長計測手段、及び錨鎖の空中部分の水平長さを計測する水平長計測手段の少なくともいずれか１つの計測結果に基づいて錨鎖水平張力を導出する場合は、錨鎖の状態から錨鎖水平張力を精度よく導出することができる。 In addition, if the anchor chain horizontal tension deriving means derives the anchor chain horizontal tension based on at least one of the measurement results of the anchor chain angle measuring means that measures the vertical (up and down) angle of the anchor chain at the anchor chain mouth, the aerial length measuring means that measures the aerial length of the anchor chain, and the horizontal length measuring means that measures the horizontal length of the aerial portion of the anchor chain, the anchor chain horizontal tension can be derived with high accuracy from the state of the anchor chain.
また、錨泊支援を行う報知手段をさらに備え、走錨危険性推定手段の推定結果を報知手段を用いて報知する場合は、船長等に走錨の危険性の推定結果を提供することができる。 In addition, if a notification means for providing anchoring assistance is further provided and the results of the anchor dragging risk estimation means are notified using the notification means, the estimated results of the anchor dragging risk can be provided to the captain, etc.
また、報知手段として表示手段を用い、限界把駐力導出手段で導出された限界把駐力と、錨鎖水平張力導出手段で導出された錨鎖水平張力を時系列的に表示し、走錨の危険性を限界把駐力と錨鎖水平張力の差分として表示する場合は、船長等は、錨鎖水平張力が刻々変化することによる限界把駐力と錨鎖水平張力との差分の増減傾向を時系列的に表示された限界把駐力と錨鎖水平張力から把握しやすくなり、また表示された差分により走錨の危険性を正確に把握しやすくなるため、走錨を防ぐための対応をより的確に行うことができる。 In addition, when a display means is used as the notification means to display the limit holding force derived by the limit holding force derivation means and the horizontal anchor chain tension derived by the horizontal anchor chain tension derivation means in a time series and to display the risk of anchor dragging as the difference between the limit holding force and the horizontal anchor chain tension, the captain, etc. can easily grasp the increase/decrease trend of the difference between the limit holding force and the horizontal anchor chain tension due to the moment-to-moment change in the horizontal anchor chain tension from the limit holding force and horizontal anchor chain tension displayed in a time series, and the displayed difference makes it easier to accurately grasp the risk of anchor dragging, so that measures to prevent anchor dragging can be taken more appropriately.
また、差分に閾値を設け、走錨の危険性が所定の閾値以下になった場合、または差分の閾値に近づく速度を判断して、警報をして報知する場合は、警報により船長等に走錨を防ぐための対応を的確に促すことができる。特に、差分の閾値に近づく速度を判断して警報する場合は、走錨の危険性の状況変化に対応して緊急に報知することができる。 In addition, if a threshold is set for the difference, and an alarm is issued when the risk of anchor dragging falls below a specified threshold, or when the speed is judged to be approaching the difference threshold, the alarm can accurately prompt the captain, etc. to take action to prevent anchor dragging. In particular, if an alarm is issued based on the speed being approached to the difference threshold, an emergency alarm can be issued in response to changes in the risk of anchor dragging.
以下に、本発明の実施形態による錨泊支援方法及び錨泊支援システムについて説明する。 The anchoring support method and anchoring support system according to an embodiment of the present invention are described below.
図１は錨泊時を３つの状態に分けて示した図であり、（ａ）は第一の状態、（ｂ）は第二の状態、（ｃ）は第三の状態を示している。
船舶１は、水底２におろされる錨１０と、先端が錨１０と接続し後端が船舶１と接続した錨鎖２０を有する。錨鎖２０は、船舶１の船首部に設けられた錨鎖口３０から繰り出される。
錨１０が水底２におりると、錨鎖２０は船舶１と錨１０との間で懸垂曲線を描く。本実施形態では、懸垂曲線を描く錨１０と錨鎖２０の状況を、第一の状態、第二の状態、及び第三の状態の３つの状態に分ける。
錨１０と船舶１との水平距離は、第一の状態が最も近く、第三の状態が最も離れている。図１中の▼は、錨鎖２０の立ち上がり位置Ａを示している。
FIG. 1 is a diagram showing three states during anchoring, where (a) shows a first state, (b) shows a second state, and (c) shows a third state.
The ship 1 has an anchor 10 that is lowered to the bottom of the water 2, and an anchor chain 20 whose front end is connected to the anchor 10 and whose rear end is connected to the ship 1. The anchor chain 20 is let out from an anchor chain port 30 provided at the bow of the ship 1.
When the anchor 10 descends to the bottom of the water 2, the anchor chain 20 forms a catenary curve between the ship 1 and the anchor 10. In this embodiment, the state of the anchor 10 and the anchor chain 20 forming the catenary curve is divided into three states: a first state, a second state, and a third state.
The horizontal distance between the anchor 10 and the ship 1 is closest in the first state and is farthest in the third state. ▼ in Fig. 1 indicates the rising position A of the anchor chain 20.
図１（ａ）に示す第一の状態は、錨鎖２０の一部が水底２に横たわった状態である。第一の状態では、錨鎖２０の立ち上がり位置Ａは水底２上となる。錨鎖２０は、立ち上がり位置Ａにおいて水平（水底２と平行）であり、水底２から角度０（ゼロ）で立ち上がっている。
図１（ｂ）に示す第二の状態は、錨鎖２０が水底２に横たわっておらず、錨鎖２０が水底２から角度０（ゼロ）で立ち上がった状態である。第二の状態では、錨鎖２０の立ち上がり位置Ａは錨１０との接続部となる。錨鎖２０は、立ち上がり位置Ａにおいて水平（水底２と平行）である。
図１（ｃ）に示す第三の状態は、錨鎖２０が水底２に横たわっておらず、錨鎖２０が水底２から０度よりも大きい角度θで立ち上がった状態である。第三の状態では、錨鎖２０の立ち上がり位置Ａは錨１０との接続部となる。錨鎖２０は、立ち上がり位置Ａにおいて水底２に対して傾いている。
1(a) is a state in which a part of the anchor chain 20 is lying on the water bottom 2. In the first state, a rising position A of the anchor chain 20 is on the water bottom 2. The anchor chain 20 is horizontal (parallel to the water bottom 2) at the rising position A, and rises from the water bottom 2 at an angle of 0 (zero).
1(b) is a state in which the anchor chain 20 is not lying on the water bottom 2, but rises from the water bottom 2 at an angle of 0 (zero). In the second state, the rising position A of the anchor chain 20 is the connection part with the anchor 10. The anchor chain 20 is horizontal (parallel to the water bottom 2) at the rising position A.
1(c) is a state in which the anchor chain 20 does not lie on the water bottom 2, but rises from the water bottom 2 at an angle θ greater than 0 degrees. In the third state, the rising position A of the anchor chain 20 is the connection part with the anchor 10. The anchor chain 20 is inclined with respect to the water bottom 2 at the rising position A.
本実施形態では、水深と水底土質等を考慮した上で、伸出錨鎖長さｋに応じて３つの状態の内のどの状態で限界把駐力Ｔｈ
＊が現れるか、すなわちどの状態で走錨が発生するかを判断すると共に、その限界把駐力Ｔｈ
＊の値を導出する。なお、水底土質は海図等から判断する。
第一から第三の状態の内どの状態で走錨が発生するかの判断と、限界把駐力Ｔｈ
＊の導出には、錨１０と錨鎖２０の性能、水底土質、水深、及び伸出錨鎖長さｋを用いる。錨１０と錨鎖２０の性能、水底土質、及び水深は、船舶１（錨１０、錨鎖２０）と錨泊地から決まり、伸出錨鎖長さｋ［ｍ］は、船長等の判断によって決まる。
In this embodiment, taking into consideration the water depth and the soil quality of the bottom of the water, a determination is made as to which of the three conditions, depending on the length of the extended anchor chain k, will result in the critical holding force T h * , i.e., in which condition the anchor will drag, and the value of the critical holding force T h * will be derived. The soil quality of the bottom of the water will be determined from a nautical chart, etc.
The performance of the anchor 10 and the anchor chain 20, the bottom soil quality, the water depth, and the extended anchor chain length k are used to determine which of the first to third conditions will cause anchor dragging and to derive the limit holding force T h * . The performance of the anchor 10 and the anchor chain 20, the bottom soil quality, and the water depth are determined by the ship 1 (anchor 10, anchor chain 20) and the anchorage, and the extended anchor chain length k [m] is determined by the judgment of the captain, etc.
第一から第三の状態の内、どの状態で限界把駐力Ｔｈ
＊が現れるか、すなわちどの状態で走錨が発生するかを判断するにあたっては、次式（１）に示すように、状態分岐錨鎖長さｋｃ［ｍ］が重要な役割をもつ。
式（１）に示すように、伸出錨鎖長さｋが状態分岐錨鎖長さｋｃよりも長い場合は第一の状態で限界把駐力Ｔｈ
＊が現れ、伸出錨鎖長さｋが状態分岐錨鎖長さｋｃと等しい場合は第二の状態で限界把駐力Ｔｈ
＊が現れ、伸出錨鎖長さｋが状態分岐錨鎖長さｋｃよりも短い場合は第三の状態で限界把駐力Ｔｈ
＊が現れる。このように、伸出錨鎖長さｋを状態分岐錨鎖長さｋｃと比較することで、走錨が第一から第三の状態のいずれの状態で発生するかを判断することができる。
In determining in which of the first to third states the limiting holding force T h * appears, i.e., in which state the anchor dragging occurs, the state branch anchor chain length k c [m] plays an important role as shown in the following formula (1).
As shown in formula (1), when the extended anchor chain length k is longer than the state branch anchor chain length kc , the limit holding force T h * appears in the first state, when the extended anchor chain length k is equal to the state branch anchor chain length kc , the limit holding force T h * appears in the second state, and when the extended anchor chain length k is shorter than the state branch anchor chain length kc , the limit holding force T h * appears in the third state. In this way, by comparing the extended anchor chain length k with the state branch anchor chain length kc , it is possible to determine in which of the first to third states the anchor dragging will occur.
３つの状態ごとの限界把駐力Ｔｈ
＊を導出するにあたっては、それぞれの状態に適した計算式を適用する。限界把駐力Ｔｈ
＊を３つの状態に分けて導出することで、各状態における限界把駐力Ｔｈ
＊を精度よく導出することができる。
第一の状態の限界把駐力Ｔｈ
＊は、次式（３）に基づいて導出する。
The limit holding force T h * in the first state is derived based on the following equation (3).
第二の状態の限界把駐力Ｔｈ
＊は、次式（４）に基づいて導出する。
第三の状態の限界把駐力Ｔｈ
＊は、次式（５）に基づいて導出する。
なお、式（３）から式（５）は次式（Ａ１）を解くことによって求めることができる。
また、錨鎖２０は水面３より下側の水中部分と水面３より上側の空中部分とからなり、水中重量と空中重量は異なるため水底２から錨鎖口３０までの曲線は厳密には懸垂曲線にはならない。本実施形態ではこの重量の違いの影響を小さいと仮定して伸出錨鎖長さｋ全体に亘って水中重量をもとに懸垂曲線を考えているが、より正確な判断を行うために水中重量と空中重量の違いによる影響を考慮することもできる。 In addition, the anchor chain 20 consists of an underwater portion below the water surface 3 and an aerial portion above the water surface 3, and because the underwater weight and the aerial weight are different, the curve from the bottom of the water 2 to the anchor chain mouth 30 is not strictly a catenary curve. In this embodiment, the effect of this difference in weight is assumed to be small, and the catenary curve is considered based on the underwater weight over the entire extended anchor chain length k, but to make a more accurate judgment, the effect of the difference between the underwater weight and the aerial weight can also be taken into account.
また、錨鎖２０には自重と張力によって伸びが発生する。本実施形態では錨鎖２０の伸びの影響を小さいと仮定して無視して懸垂曲線を考えているが、より正確な判断を行うために伸びの影響を考慮することもできる。 The anchor chain 20 also stretches due to its own weight and tension. In this embodiment, the effect of the stretch of the anchor chain 20 is assumed to be small and ignored when considering the catenary curve, but the effect of the stretch can also be taken into account to make a more accurate judgment.
また、錨鎖張力の鉛直成分によって船の喫水とりわけ船首喫水が変化することが考えられる。本実施形態では喫水の変化の影響は無視しているが、より正確な判断を行うために喫水の変化による影響を考慮することもできる。 It is also possible that the vertical component of the anchor cable tension will change the ship's draft, particularly the bow draft. In this embodiment, the effect of changes in draft is ignored, but the effect of changes in draft can also be taken into account to make a more accurate judgment.
走錨の危険性の評価は、限界把駐力Ｔｈ
＊と時々刻々の錨鎖水平張力Ｔｈとを比較して判断する。そのため、錨泊中の錨鎖水平張力Ｔｈを、計測により求めるか、又は推定する必要がある。
計測により求める場合は、錨鎖２０にかかる張力を張力計等で計測し、計測結果に基づいてその水平成分である錨鎖水平張力Ｔｈを求める。錨鎖２０にかかる張力を計測することで、張力の計測結果に基づいて錨鎖水平張力Ｔｈを精度よく求めることができる。
また、推定する場合は、錨鎖口３０における錨鎖鉛直（上下）角度θＨ、錨鎖２０の空中長さｓ１、及び錨鎖２０の空中部分の水平距離ｂの少なくともいずれか一つを計測し、計測結果から錨鎖水平張力Ｔｈを推定する。これにより、錨鎖２０の状態から錨鎖水平張力Ｔｈを精度よく推定することができる。
The risk of dragging an anchor is assessed by comparing the anchor holding force limit T h * with the horizontal tension T h of the anchor chain at every moment. Therefore, the horizontal tension T h of the anchor chain while anchored must be measured or estimated.
When determining by measurement, the tension applied to the anchor chain 20 is measured with a tension meter or the like, and the horizontal component, that is, the horizontal anchor chain tension T h is determined based on the measurement results. By measuring the tension applied to the anchor chain 20, the horizontal anchor chain tension T h can be determined with high accuracy based on the tension measurement results.
In addition, when estimating, at least one of the anchor chain vertical (up and down) angle θ H at the anchor chain opening 30, the aerial length s 1 of the anchor chain 20, and the horizontal distance b of the aerial portion of the anchor chain 20 is measured, and the anchor chain horizontal tension T h is estimated from the measurement results. This makes it possible to accurately estimate the anchor chain horizontal tension T h from the state of the anchor chain 20.
また、錨鎖口３０における錨鎖鉛直（上下）角度θＨ、錨鎖２０の空中長さｓ１、又は錨鎖２０の空中部分の水平距離ｂを計測する場合は、それらの限界把駐力Ｔｈ
＊に対応する値をθＨ
＊、ｓ１
＊、ｂ＊とすると、錨鎖水平張力Ｔｈを含めて次式（９）、次式（１０）、次式（１１）、又は次式（１２）で走錨までの危険余裕を評価することができる。このように、走錨の危険性を、限界把駐力Ｔｈ
＊時と現在の錨鎖鉛直（上下）角度θＨ、錨鎖２０の空中長さｓ１、又は錨鎖２０の空中部分の水平長さｂを用いて評価することができる。
以上のように、錨鎖２０の伸出錨鎖長さｋにより異なる限界把駐力Ｔｈ ＊と、錨鎖２０にかかる錨鎖水平張力Ｔｈとを比較して、走錨の危険性を評価することで、錨鎖２０の伸出錨鎖長さｋを考慮した精度の高い限界把駐力Ｔｈ ＊と、錨鎖水平張力Ｔｈとを用いて走錨の危険性を的確に評価することができる。 As described above, by comparing the limit holding force T h * , which varies depending on the extended anchor chain length k of the anchor chain 20, with the horizontal anchor chain tension T h applied to the anchor chain 20 to evaluate the risk of anchor dragging, it is possible to accurately evaluate the risk of anchor dragging using the highly accurate limit holding force T h * that takes into account the extended anchor chain length k of the anchor chain 20 and the horizontal anchor chain tension T h .
図２は某船舶の某錨泊地における伸出錨鎖長さと限界把駐力の関係を示した図であり、横軸は伸出錨鎖長さ［ｍ］、縦軸は限界把駐力［ｋＮ］である。
船舶１が備える錨１０及び錨鎖２０の仕様・性能と錨泊地の水底土質によって、錨１０の水中重量ｗａ、錨鎖２０の単位長さ当たり水中重量ｗｃ、錨１０の把駐力係数ｒａ、及び錨鎖２０の把駐力係数ｒｃが決まるので、図２に示す限界把駐力Ｔｈ
＊と伸出錨鎖長さｋの関係が求まる。船長等は、錨泊中の最大風速の予想値等を考慮して図２をもとに必要な限界把駐力Ｔｈ
＊を推定し、推定した限界把駐力Ｔｈ
＊を確保する伸出錨鎖長さｋを決めることができる。
図２中の長破線は第一の状態の計算式（式（３））を用いて導出した限界把駐力Ｔｈ
＊を示し、●は第二の状態の計算式（式（４））を用いて導出した限界把駐力Ｔｈ
＊を示し、短破線は第三の状態の計算式（式（５））を用いて導出した限界把駐力Ｔｈ
＊を示している。また、実線は採用する限界把駐力Ｔｈ
＊を示している。
上述した通り、３つの状態のうちどの状態で限界把駐力Ｔｈ
＊が現れるかは、式（１）に示す伸出錨鎖長さｋと状態分岐錨鎖長さｋｃとの関係から判断できる。図２においては、状態分岐錨鎖長さｋｃは約１９０［ｍ］である。伸出錨鎖長さｋが状態分岐錨鎖長さｋｃよりも大きい場合は第一の状態で限界把駐力Ｔｈ
＊が現れ、伸出錨鎖長さｋが状態分岐錨鎖長さｋｃよりも短い場合は第三の状態で限界把駐力Ｔｈ
＊が現れるため、伸出錨鎖長さｋと状態分岐錨鎖長さｋｃが等しい第二の状態を境として、それよりも右側では式（３）を用いて導出した限界把駐力Ｔｈ
＊を採用し、左側では式（５）を用いて導出した限界把駐力Ｔｈ
＊を採用する。また、第二の状態では式（４）を用いて導出した限界把駐力Ｔｈ
＊を採用する。
例えば伸出錨鎖長さｋが約１２０［ｍ］の場合は、ｋ＜ｋｃであるから、第三の状態で限界把駐力Ｔｈ
＊が現れ、このときの限界把駐力Ｔｈ
＊は２００［ｋＮ］となる（図２に示す▲の位置）。このように、図２の▲に対応する伸出錨鎖長さｋを選択したとき、自動的にこれに対応した限界把駐力Ｔｈ
＊が決まる。
Figure 2 shows the relationship between the length of extended anchor chain and the maximum holding force at a certain anchorage of a certain ship, with the horizontal axis representing the length of extended anchor chain [m] and the vertical axis representing the maximum holding force [kN].
The underwater weight w a of the anchor 10, the underwater weight per unit length w c of the anchor chain 20, the holding power coefficient r a of the anchor 10, and the holding power coefficient r c of the anchor chain 20 are determined by the specifications and performance of the anchor 10 and anchor chain 20 provided on the ship 1 and the bottom soil quality of the anchoring area, so the relationship between the limit holding power T h * and the extended anchor chain length k shown in Figure 2 can be obtained. The captain or other personnel can estimate the necessary limit holding power T h * based on Figure 2, taking into account the expected maximum wind speed during anchoring, and can determine the extended anchor chain length k that will ensure the estimated limit holding power T h * .
2, the long dashed line indicates the limit holding force T h * derived using the calculation formula (3) for the first state, the black dots indicate the limit holding force T h * derived using the calculation formula (4) for the second state, and the short dashed line indicates the limit holding force T h * derived using the calculation formula (5) for the third state. Also, the solid line indicates the limit holding force T h * to be adopted.
As described above, in which of the three states the limit holding force T h * appears can be determined from the relationship between the extended anchor chain length k and the state branch anchor chain length k c shown in formula (1). In Fig. 2, the state branch anchor chain length k c is about 190 [m]. When the extended anchor chain length k is longer than the state branch anchor chain length k c , the limit holding force T h * appears in the first state, and when the extended anchor chain length k is shorter than the state branch anchor chain length k c , the limit holding force T h * appears in the third state. Therefore, the limit holding force T h * derived using formula (3) is adopted on the right side of the second state where the extended anchor chain length k and the state branch anchor chain length k c are equal, and the limit holding force T h * derived using formula (5) is adopted on the left side. In the second state, the limit holding force T h * derived using formula (4) is adopted.
For example, when the extended anchor cable length k is about 120 m, k< kc , so the limit holding force T h * appears in the third state, and the limit holding force T h * at this time is 200 kN (position ▲ shown in Figure 2). In this way, when the extended anchor cable length k corresponding to ▲ in Figure 2 is selected, the corresponding limit holding force T h * is automatically determined.
図３は水平外力と錨及び錨鎖の把駐力との関係を示した図であり、横軸は水平外力［ｋＮ］、縦軸は把駐力［ｋＮ］である。
図３中の実線は式（Ａ２）、式（Ａ３）、及び式（Ａ４）で表される公称把駐力ｆ(Ｔｈ)を示し、破線は（錨泊に必要な）把駐力［ｋＮ］（又は（錨泊に必要な）錨鎖水平張力Ｔｈ［ｋＮ］）を示す。
走錨が発生するまでは（錨泊に必要な）把駐力は水平外力に等しく釣り合い状態にあるはずなので、縦軸と横軸のスケールを合わせれば破線は傾き４５度の線になる。一方、水平外力が大きくなると錨鎖２０は水底２に横たわっている部分が少なくなり、さらに錨鎖２０の水底２に横たわっている部分がなくなって以降は錨１０に上向きの力が働くので、公称把駐力ｆ(Ｔｈ)は水平外力の増加に伴って減少する。
図３中の★は限界把駐力Ｔｈ
＊を表し、◆は現在の（錨泊に必要な）把駐力（又は（錨泊に必要な）錨鎖水平張力Ｔｈ）を表す。破線で示す（錨泊に必要な）把駐力が実線で示す公称把駐力ｆ(Ｔｈ)を超えたときにと走錨が発生すると考えられる。錨鎖水平張力Ｔｈはこの公称把駐力ｆ(Ｔｈ)を超えることはできない。したがって実線と破線の交点★が限界把駐力Ｔｈ
＊に対応する。また、図３中の⇔は把駐力の危険余裕ΔＴｈ
＊を表している。把駐力の危険余裕ΔＴｈ
＊は、現在の（錨泊に必要な）把駐力（又は（錨泊に必要な）錨鎖水平張力Ｔｈ）と限界把駐力Ｔｈ
＊との差である。
図３では、水平外力が約１２０［ｋＮ］のときに錨鎖２０が水底２に横たわらず角度０で立ち上がる第二の状態となる。
水平外力が更に増加して第三の状態となった場合でも、錨鎖２０が錨１０を上方に引く影響を考慮しなければ、公称把駐力ｆ(Ｔｈ)は第二の状態のときと変わらず一定となる。また、仮に錨鎖２０が錨１０を上方に引く影響を考慮したとしても、従来のように水底２から錨鎖２０が立ち上がる角度と錨１０の把駐力の関係を用いると繰り返し計算が必要となり限界把駐力Ｔｈ
＊を陽に求められず効率が悪い。また、どのような条件で錨鎖２０のすべてが懸垂曲線を描くかの検討も困難である。
これに対して本実施形態では、第三の状態では錨鎖２０が錨１０を上方に引くことを錨１０の見掛けの重量が減少したと見なし、錨鎖張力の上向き成分が錨１０の把駐力におよぼす影響を表す係数αを導入することによって、第三の状態でも陽に限界把駐力Ｔｈ
＊の推定を可能としている。
FIG. 3 is a diagram showing the relationship between horizontal external force and the holding force of the anchor and anchor chain, with the horizontal axis representing the horizontal external force [kN] and the vertical axis representing the holding force [kN].
The solid lines in FIG. 3 indicate the nominal holding force f (Th) expressed by formulas (A2), (A3), and (A4), and the dashed lines indicate the holding force [kN] (required for anchoring) (or the horizontal anchor chain tension T h [kN] (required for anchoring)).
Until the anchor drags, the holding force (necessary for anchoring) should be equal to the horizontal external force and in a balanced state, so if the scales of the vertical and horizontal axes are matched, the dashed line will be a line with a 45 degree inclination. On the other hand, as the horizontal external force increases, less of the anchor chain 20 is lying on the bottom 2, and after the portion of the anchor chain 20 lying on the bottom 2 disappears, an upward force acts on the anchor 10, so the nominal holding force f (Th) decreases as the horizontal external force increases.
In Figure 3, ★ represents the limit holding force T h * , and ◆ represents the current holding force (necessary for anchoring) (or horizontal anchor chain tension T h (necessary for anchoring)). It is believed that anchor dragging will occur when the holding force (necessary for anchoring) shown by the dashed line exceeds the nominal holding force f (Th) shown by the solid line. The horizontal anchor chain tension T h cannot exceed this nominal holding force f (Th) . Therefore, the intersection ★ of the solid line and dashed line corresponds to the limit holding force T h * . Also, ⇔ in Figure 3 represents the risk margin of holding force ΔT h * . The risk margin of holding force ΔT h * is the difference between the current holding force (necessary for anchoring) (or horizontal anchor chain tension T h (necessary for anchoring)) and the limit holding force T h * .
In FIG. 3, when the horizontal external force is about 120 kN, the anchor chain 20 enters a second state in which it stands at an angle of 0 and does not lie on the bottom 2 .
Even if the horizontal external force further increases to the third state, if the effect of the anchor chain 20 pulling the anchor 10 upward is not taken into consideration, the nominal holding force f (Th) will remain constant as in the second state. Even if the effect of the anchor chain 20 pulling the anchor 10 upward is taken into consideration, repeated calculations are required if the relationship between the angle at which the anchor chain 20 rises from the bottom 2 and the holding force of the anchor 10 is used as in the past, and the limit holding force T h * cannot be obtained explicitly, which is inefficient. In addition, it is difficult to consider under what conditions the entire anchor chain 20 will draw a catenary curve.
In contrast to this, in the present embodiment, in the third state, the anchor chain 20 pulling the anchor 10 upward is regarded as a decrease in the apparent weight of the anchor 10, and by introducing a coefficient α which represents the effect of the upward component of the anchor chain tension on the holding force of the anchor 10, it is possible to explicitly estimate the limit holding force T h * even in the third state.
図４は錨鎖水平張力と錨鎖鉛直（上下）角度との関係を示した図であり、横軸は水平外力［ｋＮ］、縦軸は錨鎖鉛直角度［ｄｅｇ］である。
θＨ
＊は、限界把駐力Ｔｈ
＊時における錨鎖鉛直（上下）角度である。錨鎖鉛直（上下）角度θＨが限界把駐力Ｔｈ
＊時における錨鎖鉛直（上下）角度θＨ
＊に達することは、水平外力（錨鎖水平張力Ｔｈ）が限界把駐力Ｔｈ
＊に達することと同値である。
水平外力が大きくなると船舶１と錨１０との距離が離れて錨鎖鉛直（上下）角度θＨは小さくなる。図４では錨鎖鉛直（上下）角度θＨが約２０度を下回ったときに走錨が発生する（図４中の★）。図４中の◆は現在の錨鎖鉛直（上下）角度θＨを表し、縦向きの⇔は錨鎖鉛直（上下）角度の危険余裕ΔθＨ
＊を表し、横向きの⇔は把駐力の危険余裕ΔＴｈ
＊を表している。
錨鎖鉛直（上下）角度の危険余裕ΔθＨ
＊は、現在の錨鎖鉛直（上下）角度θＨと限界把駐力Ｔｈ
＊時における錨鎖鉛直（上下）角度θＨ
＊との差分である。把駐力の危険余裕ΔＴｈ
＊は、現在の把駐力と限界把駐力Ｔｈ
＊との差分である。
図４に示すように、走錨の危険度又は走錨までの余裕を、錨鎖鉛直（上下）角度θＨを用いて評価することができる。このことは、伸出錨鎖長さｋにより異なる限界把駐力Ｔｈ
＊と、錨鎖２０にかかる錨鎖水平張力Ｔｈとを比較して走錨の危険性を評価することと等価となる。
FIG. 4 is a diagram showing the relationship between the horizontal tension of the anchor chain and the vertical (up and down) angle of the anchor chain, with the horizontal axis representing the horizontal external force [kN] and the vertical axis representing the vertical angle of the anchor chain [deg].
θ H * is the anchor chain vertical (up and down) angle at the time of the limit holding force T h * . When the anchor chain vertical (up and down) angle θ H reaches the anchor chain vertical (up and down) angle θ H * at the time of the limit holding force T h * , it is the same as when the horizontal external force (anchor chain horizontal tension T h ) reaches the limit holding force T h * .
When the horizontal external force increases, the distance between the ship 1 and the anchor 10 increases and the anchor chain vertical (up and down) angle θH decreases. In Figure 4, anchor dragging occurs when the anchor chain vertical (up and down) angle θH falls below approximately 20 degrees (★ in Figure 4). In Figure 4, ◆ represents the current anchor chain vertical (up and down) angle θH , the vertical ⇔ represents the risk margin ΔθH * of the anchor chain vertical (up and down) angle, and the horizontal ⇔ represents the risk margin ΔT h * of the holding force.
The risk margin Δθ H * of the anchor chain vertical (up and down) angle is the difference between the current anchor chain vertical (up and down) angle θ H and the anchor chain vertical (up and down) angle θ H * at the time of the limit holding force T h * . The risk margin ΔT h * of the holding force is the difference between the current holding force and the limit holding force T h * .
As shown in Figure 4, the risk of anchor dragging or the margin of safety before anchor dragging can be evaluated using the anchor chain vertical (up and down) angle θ H. This is equivalent to evaluating the risk of anchor dragging by comparing the limit holding force T h * , which differs depending on the extended anchor chain length k, with the horizontal tension T h of the anchor chain applied to the anchor chain 20.
図５は錨鎖水平張力と錨鎖の空中長さとの関係を示した図であり、横軸は水平外力［ｋＮ］、縦軸は錨鎖２０の空中長さｓ１［ｍ］である。
ｓ１
＊は、限界把駐力Ｔｈ
＊時における錨鎖２０の空中長さである。錨鎖２０の空中長さｓ１が限界把駐力Ｔｈ
＊時における錨鎖２０の空中長さｓ１
＊に達することは、水平外力（錨鎖水平張力Ｔｈ）が限界把駐力Ｔｈ
＊に達することと同値である。
水平外力が大きくなると錨鎖鉛直（上下）角度θＨが小さくなるため錨鎖２０の空中長さｓ１が長くなる。図５では、錨鎖２０の空中長さｓ１が約１７ｍを上回ったときに走錨が発生する（図５中の★）。図５中の◆は現在の錨鎖２０の空中長さｓ１を表し、縦向きの⇔は錨鎖２０の空中長さの危険余裕Δｓ１
＊を表し、横向きの⇔は把駐力の危険余裕ΔＴｈ
＊を表している。
錨鎖２０の空中長さの危険余裕Δｓ１
＊は、現在の錨鎖２０の空中長さｓ１と限界把駐力Ｔｈ
＊時における錨鎖２０の空中長さｓ１
＊との差分である。
図５に示すように、走錨の危険度又は走錨までの余裕を、錨鎖２０の空中長さｓ１を用いて評価することができる。このことは、伸出錨鎖長さｋにより異なる限界把駐力Ｔｈ
＊と、錨鎖２０にかかる錨鎖水平張力Ｔｈとを比較して走錨の危険性を評価することと等価となる。
FIG. 5 is a diagram showing the relationship between the horizontal tension of the anchor chain and the length of the anchor chain in the air, with the horizontal axis representing the horizontal external force [kN] and the vertical axis representing the length s 1 of the anchor chain 20 in the air [m].
s 1 * is the length in the air of the anchor chain 20 at the limit holding force T h * . When the length in the air s 1 of the anchor chain 20 reaches the length in the air s 1 * of the anchor chain 20 at the limit holding force T h * , this is the same as when the horizontal external force (horizontal anchor chain tension T h ) reaches the limit holding force T h * .
When the horizontal external force increases, the anchor chain vertical (up and down) angle θH decreases, and the length s1 of the anchor chain 20 in the air becomes longer. In Figure 5, anchor dragging occurs when the length s1 of the anchor chain 20 in the air exceeds approximately 17m (★ in Figure 5). In Figure 5, ◆ represents the current length s1 of the anchor chain 20 in the air, the vertical ⇔ represents the risk margin Δs1 * of the length of the anchor chain 20 in the air, and the horizontal ⇔ represents the risk margin ΔT h * of the holding force.
The risk margin Δs 1 * of the length of the anchor chain 20 in the air is the difference between the current length s 1 of the anchor chain 20 in the air and the length s 1 * of the anchor chain 20 in the air at the time of the limit holding force T h * .
As shown in Fig. 5, the risk of anchor dragging or the margin of safety before anchor dragging can be evaluated using the aerial length s1 of the anchor chain 20. This is equivalent to evaluating the risk of anchor dragging by comparing the limit holding force T h * , which varies depending on the extended anchor chain length k, with the horizontal tension T h applied to the anchor chain 20.
図６は錨鎖水平張力と錨鎖の空中部分の水平長さとの関係を示した図であり、横軸は水平外力［ｋＮ］、縦軸は錨鎖２０の空中部分の水平長さｂ［ｍ］である。
ｂ＊は、限界把駐力Ｔｈ
＊時における錨鎖２０の空中部分の水平長さである。錨鎖２０の空中部分の水平長さｂが限界把駐力Ｔｈ
＊時における錨鎖２０の空中部分の水平長さｂ＊に達することは、水平外力（錨鎖水平張力Ｔｈ）が限界把駐力Ｔｈ
＊に達することと同値である。
水平外力が大きくなると錨鎖鉛直（上下）角度θＨが小さくなるため錨鎖２０の空中部分の水平長さｂが長くなる。図６では、錨鎖２０の空中部分の水平長さｂが約１６ｍを上回ったときに走錨が発生する（図６中の★）。図６中の◆は現在の錨鎖２０の空中部分の水平長さｂを表し、縦向きの⇔は錨鎖２０の空中部分の水平長さの危険余裕Δｂ＊を表し、横向きの⇔は把駐力の危険余裕ΔＴｈ
＊を表している。
錨鎖２０の空中部分の水平長さの危険余裕Δｂ＊は、現在の錨鎖２０の空中部分の水平長さｂと限界把駐力Ｔｈ
＊時における錨鎖２０の空中部分の水平長さｂ＊との差分である。
図６に示すように、走錨の危険度又は走錨までの余裕を、錨鎖２０の空中部分の水平長さｂを用いて評価することができる。このことは、伸出錨鎖長さｋにより異なる限界把駐力Ｔｈ
＊と、錨鎖２０にかかる錨鎖水平張力Ｔｈとを比較して走錨の危険性を評価することと等価となる。
FIG. 6 is a diagram showing the relationship between the horizontal tension of the anchor chain and the horizontal length of the aerial portion of the anchor chain, where the horizontal axis is the horizontal external force [kN] and the vertical axis is the horizontal length b [m] of the aerial portion of the anchor chain 20.
b * is the horizontal length of the air portion of the anchor chain 20 at the limit holding force T h * . When the horizontal length b of the air portion of the anchor chain 20 reaches the horizontal length b * of the air portion of the anchor chain 20 at the limit holding force T h * , this is the same as the horizontal external force (horizontal anchor chain tension T h ) reaching the limit holding force T h * .
When the horizontal external force increases, the anchor chain vertical (up and down) angle θH decreases, so the horizontal length b of the airborne portion of the anchor chain 20 increases. In Figure 6, anchor dragging occurs when the horizontal length b of the airborne portion of the anchor chain 20 exceeds approximately 16 m (★ in Figure 6). In Figure 6, ◆ represents the current horizontal length b of the airborne portion of the anchor chain 20, the vertical ⇔ represents the risk margin Δb * of the horizontal length of the airborne portion of the anchor chain 20, and the horizontal ⇔ represents the risk margin ΔT h * of the holding force.
The risk margin Δb * of the horizontal length of the air portion of the anchor chain 20 is the difference between the current horizontal length b of the air portion of the anchor chain 20 and the horizontal length b * of the air portion of the anchor chain 20 at the time of the limit holding force T h * .
As shown in Figure 6, the risk of anchor dragging or the margin of safety before anchor dragging can be evaluated using the horizontal length b of the aerial portion of the anchor chain 20. This is equivalent to evaluating the risk of anchor dragging by comparing the limit holding force T h * , which varies depending on the extended anchor chain length k, with the horizontal tension T h of the anchor chain 20.
図７は錨鎖水平張力と把駐力の危険余裕の時間的推移を例示した図であり、縦軸は把駐力、横軸は時間である。
図７中の点線は限界把駐力Ｔｈ
＊を表し、曲線は錨鎖水平張力Ｔｈを表している。錨鎖水平張力Ｔｈは風や波の状態によって刻々と変動するが、図７に示すように、限界把駐力Ｔｈ
＊と錨鎖水平張力Ｔｈを時系列的に表示することで、船長等は、錨鎖水平張力Ｔｈが刻々変化することによる限界把駐力Ｔｈ
＊と錨鎖水平張力Ｔｈとの差分ΔＴｈ
＊の増減傾向を把握しやすくなるため、走錨の危険性を把握して走錨を防ぐための対応をより的確に行うことができる。また、現時点における限界把駐力Ｔｈ
＊と錨鎖水平張力Ｔｈとの差である把駐力の危険余裕ΔＴｈ
＊を併せて表示することで、船長等に走錨の危険性をより正確に知らせることができる。また、把駐力の危険余裕（差分）ΔＴｈ
＊に所定の閾値を設け、把駐力の危険余裕（差分）ΔＴｈ
＊が閾値以下となった場合に警報を発することで、船長等に走錨を防ぐための対応を促すことができる。なお、把駐力の危険余裕ΔＴｈ
＊の表示、走錨の危険性の報知、把駐力の危険余裕（差分）ΔＴｈ
＊に所定の閾値を設け、把駐力の危険余裕（差分）ΔＴｈ
＊が閾値以下となった場合に警報を発すること等は、図３から図６の図等を利用して行うこともできる。
FIG. 7 is a diagram showing an example of the time transition of the horizontal tension of the anchor chain and the risk margin of holding force, with the vertical axis representing holding force and the horizontal axis representing time.
The dotted line in Fig. 7 represents the limit holding force T h * , and the curve represents the horizontal tension of the anchor chain T h . The horizontal tension of the anchor chain T h fluctuates from moment to moment depending on the wind and wave conditions, but by displaying the limit holding force T h * and the horizontal tension of the anchor chain T h in a chronological order as shown in Fig. 7, the captain, etc. can easily grasp the increase/decrease tendency of the difference ΔT h * between the limit holding force T h * and the horizontal tension of the anchor chain T h due to the moment-to-moment change of the horizontal tension of the anchor chain T h , and can grasp the risk of anchor dragging and take more appropriate measures to prevent it. In addition, by also displaying the risk margin ΔT h * of the holding force, which is the difference between the limit holding force T h * at the current time and the horizontal tension of the anchor chain T h , the captain, etc. can be more accurately informed of the risk of anchor dragging. Also, by setting a predetermined threshold for the holding force danger margin (difference) ΔT h * and issuing an alarm when the holding force danger margin (difference) ΔT h * falls below the threshold, it is possible to urge the captain, etc. to take measures to prevent anchor dragging. Note that displaying the holding force danger margin ΔT h * , notifying the risk of anchor dragging, setting a predetermined threshold for the holding force danger margin (difference) ΔT h * and issuing an alarm when the holding force danger margin (difference) ΔT h * falls below the threshold, etc. can also be performed using the diagrams in Figures 3 to 6, etc.
図８は錨泊支援システムのブロック図である。
錨泊支援システムは、錨鎖２０の伸出錨鎖長さｋにより異なる限界把駐力Ｔｈ
＊を導出する限界把駐力導出手段４０と、錨鎖２０にかかる錨鎖水平張力Ｔｈを導出する錨鎖水平張力導出手段５０と、走錨の危険性を推定する走錨危険性推定手段６０と、錨鎖２０の張力を計測する張力計測手段７０と、報知手段８０を備え、錨１０と錨鎖２０を有した船舶１の錨泊を支援する。
FIG. 8 is a block diagram of the anchoring support system.
The anchoring support system comprises a limit holding force derivation means 40 which derives a limit holding force T h * which differs depending on the extended anchor chain length k of the anchor chain 20, an anchor chain horizontal tension derivation means 50 which derives the horizontal anchor chain tension T h applied to the anchor chain 20, an anchor dragging risk estimation means 60 which estimates the risk of anchor dragging, a tension measurement means 70 which measures the tension of the anchor chain 20, and an alarm means 80, and supports anchoring of a ship 1 having an anchor 10 and an anchor chain 20.
限界把駐力導出手段４０は、錨１０の水中重量ｗａ及び性能（型式、寸法）と、水底土質と、錨鎖２０の伸出錨鎖長さｋ及び単位長さ当たりの水中重量ｗｃを取得し、上述の錨泊支援方法で説明した式（１）から式（８）を用いて、第一から第三の状態の内どの状態で限界把駐力Ｔｈ ＊が現れるかを判断し、そのときの限界把駐力Ｔｈ ＊を導出する。なお、水底土質は海図等から取得する。 The limit holding force deriving means 40 obtains the underwater weight wa and performance (type, dimensions) of the anchor 10, the bottom soil quality, the extended anchor chain length k and the underwater weight per unit length wc of the anchor chain 20, and determines in which of the first to third states the limit holding force T h * appears using equations (1) to (8) described in the above anchoring support method, and derives the limit holding force T h * at that time. The bottom soil quality is obtained from a nautical chart, etc.
錨鎖水平張力導出手段５０は、張力計測手段７０の計測結果に基づいてその水平成分としての錨鎖水平張力Ｔｈを導出する。張力計測手段７０は例えば張力計である。張力計測手段７０を用いて錨鎖２０の張力を計測することで、張力の計測結果に基づいて錨鎖水平張力Ｔｈを精度よく導出することができる。
なお、錨鎖水平張力Ｔｈの算出に当たっては、張力計測手段７０の計測結果に加え、伸出錨鎖長さｋ、錨鎖２０の角度等を考慮してもよい。
また、張力計測手段７０に代えて、図８に点線で示すように、錨鎖口３０における錨鎖２０の錨鎖鉛直（上下）角度θＨを計測する錨鎖角度計測手段９０、錨鎖２０の空中長さｓ１を計測する空中長計測手段１００、及び錨鎖２０の空中部分の水平長さｂを計測する水平長計測手段１１０の少なくとも一つを設け、錨鎖水平張力導出手段５０が、錨鎖角度計測手段９０の計測結果、空中長計測手段１００の計測結果、及び水平長計測手段１１０の計測結果の少なくとも一つに基づいて、予め定めた関係式を用いて錨鎖水平張力Ｔｈを導出することもできる。これにより、錨鎖２０の状態から錨鎖水平張力Ｔｈを精度よく導出することができる。
The anchor chain horizontal tension deriving means 50 derives the anchor chain horizontal tension T h as the horizontal component based on the measurement result of the tension measuring means 70. The tension measuring means 70 is, for example, a tension meter. By measuring the tension of the anchor chain 20 using the tension measuring means 70, the anchor chain horizontal tension T h can be derived with high accuracy based on the measurement result of the tension.
In addition, when calculating the horizontal tension T h of the anchor chain, in addition to the measurement result of the tension measuring means 70, the length k of the extended anchor chain, the angle of the anchor chain 20, etc. may be taken into consideration.
8, instead of the tension measuring means 70, at least one of anchor chain angle measuring means 90 for measuring the vertical (up and down) angle θH of the anchor chain 20 at the anchor chain opening 30, air length measuring means 100 for measuring the air length s1 of the anchor chain 20, and horizontal length measuring means 110 for measuring the horizontal length b of the air portion of the anchor chain 20 may be provided, and the anchor chain horizontal tension deriving means 50 may derive the horizontal anchor chain tension T h using a predetermined relational expression based on at least one of the measurement results of the anchor chain angle measuring means 90, the measurement results of the air length measuring means 100, and the measurement results of the horizontal length measuring means 110. This makes it possible to accurately derive the horizontal anchor chain tension T h from the state of the anchor chain 20.
走錨危険性推定手段６０は、限界把駐力導出手段４０によって導出された限界把駐力Ｔｈ
＊と錨鎖水平張力導出手段５０によって導出された錨鎖水平張力Ｔｈを比較して、走錨の危険性を推定する。
また、走錨危険性推定手段６０は、限界把駐力Ｔｈ
＊と錨鎖水平張力Ｔｈとの差分（把駐力の危険余裕）ΔＴｈ
＊を導出すると共に、導出した差分（把駐力の危険余裕）ΔＴｈ
＊が所定の閾値以下か否かを判断する。
The anchor dragging risk estimating means 60 compares the limit holding force T h * derived by the limit holding force deriving means 40 with the horizontal anchor chain tension T h derived by the horizontal anchor chain tension deriving means 50 to estimate the risk of anchor dragging.
In addition, the anchor dragging risk estimation means 60 derives the difference (holding force risk margin) ΔT h * between the limit holding force T h * and the horizontal anchor chain tension T h , and determines whether the derived difference (holding force risk margin) ΔT h * is equal to or less than a predetermined threshold value.
報知手段８０は、走錨危険性推定手段６０の推定結果を報知する。これにより、船長等に走錨の危険性の推定結果を提供することができる。
報知手段８０は、表示手段８１と警報器８２を有する。表示手段８１は、例えば船橋等に設置されたモニタであり、図７のように、限界把駐力導出手段４０で導出された限界把駐力Ｔｈ
＊と、錨鎖水平張力導出手段５０で導出された錨鎖水平張力Ｔｈを時系列的に表示すると共に、走錨の危険性を限界把駐力Ｔｈ
＊と錨鎖水平張力Ｔｈの差分ΔＴｈ
＊として表示する。これにより船長等は、錨鎖水平張力Ｔｈが刻々変化することによる限界把駐力Ｔｈ
＊と錨鎖水平張力Ｔｈとの差分ΔＴｈ
＊の増減傾向を時系列的に表示された限界把駐力と錨鎖水平張力Ｔｈから把握しやすくなり、また表示された差分ΔＴｈ
＊により走錨の危険性を正確に把握しやすくなるため、走錨を防ぐための対応をより的確に行うことができる。
また、錨泊支援システムは、走錨危険性推定手段６０において差分（把駐力の危険余裕）ΔＴｈ
＊が所定の閾値以下であると判断された場合は、警報器８２から警報を発する。警報を発することにより、船長等に走錨を防ぐための対応を的確に促すことができる。
The notification means 80 notifies the result of estimation by the anchor dragging risk estimation means 60. This makes it possible to provide the captain, etc. with the estimation result of the risk of anchor dragging.
The notification means 80 has a display means 81 and an alarm 82. The display means 81 is a monitor installed on the bridge, for example, and displays the limit holding force T h * derived by the limit holding force derivation means 40 and the horizontal anchor chain tension T h derived by the horizontal anchor chain tension derivation means 50 in chronological order, as well as the risk of anchor dragging as the difference ΔT h * between the limit holding force T h * and the horizontal anchor chain tension T h . This makes it easier for the captain, etc. to grasp the increase/decrease tendency of the difference ΔT h * between the limit holding force T h * and the horizontal anchor chain tension T h due to the moment-to-moment change of the horizontal anchor chain tension T h from the limit holding force and horizontal anchor chain tension T h displayed in chronological order, and also makes it easier to accurately grasp the risk of anchor dragging from the displayed difference ΔT h * , so that measures to prevent anchor dragging can be taken more appropriately.
Furthermore, when the anchor dragging risk estimation means 60 determines that the difference (the risk margin of the holding force) ΔT h * is equal to or less than a predetermined threshold, the anchoring support system issues an alarm from the alarm device 82. By issuing an alarm, it is possible to appropriately prompt the captain or the like to take measures to prevent anchor dragging.
また、錨泊支援システムは、所定時間の間に差分（把駐力の危険余裕）ΔＴｈ
＊が閾値に近づく度合いと、そのときの速度にそれぞれ基準値を設定しておき、走錨危険性推定手段６０において、所定時間の間に差分（把駐力の危険余裕）ΔＴｈ
＊が閾値に近づく度合いが基準値を超え、かつそのときの速度が基準値を超えたと判断された場合は、警報器８２から警報を発してもよい。このように差分（把駐力の危険余裕）ΔＴｈ
＊が閾値を超える蓋然性が高いと考えられる状態で警報を発することで、走錨の危険性の状況変化に対応して緊急に報知することができる。
なお、走錨の危険性の評価に当たっては、船体の受ける風向や風速の変化、波高や波向の変化、潮流や海流の変化等を検出して、あるいは予測して評価することもできる。また、評価結果を守錨や危険回避等のための制御や操船等に反映することもできる。
The anchoring support system may also set reference values for the degree to which the difference (holding force risk margin) ΔT h * approaches the threshold value during a predetermined time and for the speed at that time, and when the dragging anchor risk estimation means 60 determines that the degree to which the difference (holding force risk margin) ΔT h * approaches the threshold value during a predetermined time exceeds the reference values and that the speed at that time exceeds the reference value, it may issue an alarm from the alarm device 82. By issuing an alarm in this way when it is considered highly likely that the difference (holding force risk margin) ΔT h * will exceed the threshold value, it is possible to give an emergency alert in response to changes in the situation regarding the risk of dragging anchor.
The risk of dragging anchor can be evaluated by detecting or predicting changes in wind direction and speed, wave height and direction, and tidal and ocean currents, etc. The results of the evaluation can also be reflected in control and maneuvering for anchor keeping and risk avoidance.
本発明は、海洋や湖沼等における錨泊中の船舶や浮体等に適用でき、走錨に起因する他船や構造物等との接触や衝突、また浅瀬や岩礁等への座礁などの重大な海難事故の発生防止に大きく寄与することができる。 The present invention can be applied to ships and floating bodies anchored in oceans, lakes, and other locations, and can contribute greatly to preventing serious marine accidents such as contact or collision with other ships or structures caused by dragging anchors, or running aground on shallow waters or reefs.
１ 船舶
２ 水底
１０ 錨
２０ 錨鎖
３０ 錨鎖口
４０ 限界把駐力導出手段
５０ 錨鎖水平張力導出手段
６０ 走錨危険性推定手段
７０ 張力計測手段
８０ 報知手段
８１ 表示手段
９０ 錨鎖角度計測手段
１００ 空中長計測手段
１１０ 水平長計測手段
ｈ 水底の錨から錨鎖口までの高さ
ｋ 伸出錨鎖長さ
ｋｃ 状態分岐錨鎖長さ
ｒａ 錨の把駐力係数
ｒｃ 錨鎖の把駐力係数
Ｔｈ 錨鎖水平張力
ｗａ 錨の水中重量
ｗｃ 錨鎖の単位長さ当たり水中重量
Ｔｈ
＊ 限界把駐力
θＨ
＊ 限界把駐力時における錨鎖鉛直（上下）角度
ｓ１
＊ 限界把駐力時における錨鎖の空中長さ
ｂ＊ 限界把駐力時における錨鎖の空中部分の水平長さ
α 錨鎖張力の上向き成分が錨の把駐力におよぼす影響を表す係数
θＨ 錨鎖鉛直（上下）角度
ｓ１ 錨鎖の空中長さ
ｂ 錨鎖の空中部分の水平長さ
ΔＴｈ
＊ 限界把駐力と錨鎖水平張力の差分（把駐力の危険余裕）
Reference Signs List 1 Ship 2 Seabed 10 Anchor 20 Anchor chain 30 Anchor chain opening 40 Means for deriving maximum holding force 50 Means for deriving horizontal tension of anchor chain 60 Means for estimating risk of anchor dragging 70 Tension measuring means 80 Notification means 81 Display means 90 Anchor chain angle measuring means 100 Aerial length measuring means 110 Horizontal length measuring means h Height from the anchor on the water bottom to the anchor chain opening k Length of extended anchor chain k c Length of branched anchor chain in state r Holding force coefficient of anchor a r Holding force coefficient of anchor chain T h Horizontal tension of anchor chain w Underwater weight of anchor a w c Underwater weight per unit length of anchor chain T h * Maximum holding force θ H * Vertical (up and down) angle of anchor chain at maximum holding force s 1 * Aerial length of anchor chain at maximum holding force b * The horizontal length of the air part of the anchor chain at the limit holding force α Coefficient expressing the effect of the upward component of the anchor chain tension on the holding force of the anchor θ H Anchor chain vertical (up and down) angle s 1 Length of the anchor chain in the air b Horizontal length of the air part of the anchor chain ΔT h * The difference between the limit holding force and the horizontal tension of the anchor chain (hazard margin of holding force)
Claims (13)
前記限界把駐力を、前記伸出錨鎖長さに基づいた式（１）及び式（２）で決まる、前記錨鎖の一部が前記水底に横たわった状態である第一の状態、前記錨鎖が前記水底に横たわっておらず前記水底から角度０で立ち上がった状態である第二の状態、前記錨鎖が前記水底に横たわっておらず前記水底から０度より大きい角度で立ち上がった状態である第三の状態の３つの状態に分けて導出することを特徴とする錨泊支援方法。
ｋ ｃ ：状態分岐錨鎖長さ［ｍ］
ｈ ：水底の錨から錨鎖口までの高さ［ｍ］
ｒ ａ ：錨の把駐力係数
ｗ ａ ：錨の水中重量［Ｎ］
ｗ ｃ ：錨鎖の単位長さ当たりの水中重量［Ｎ/ｍ］ A method for supporting anchoring of a ship having an anchor and an anchor chain, comprising: comparing a limiting holding force, which varies depending on an extended length of the anchor chain, with a horizontal tension of the anchor chain applied to the anchor chain to evaluate a risk of the anchor dragging; deriving the limiting holding force taking into consideration at least the underwater weight of the anchor, a holding force coefficient of the anchor determined by the performance of the anchor and the soil quality of the water bottom, and a state of the anchor chain lying on the water bottom ,
The anchoring support method is characterized in that the limit holding force is derived by dividing it into three states, determined by equations (1) and (2) based on the extended anchor chain length: a first state in which a part of the anchor chain is lying on the water bottom; a second state in which the anchor chain is not lying on the water bottom but rises up from the water bottom at an angle of 0 degrees; and a third state in which the anchor chain is not lying on the water bottom but rises up from the water bottom at an angle greater than 0 degrees.
k c : State branch anchor chain length [m]
h: Height from the anchor on the bottom of the water to the anchor chain opening [m]
r a : Anchor holding power coefficient
wa : Underwater weight of anchor [N]
wc : Underwater weight per unit length of anchor chain [N/m ]
ｈ ：水底の錨から錨鎖口までの高さ［ｍ］
ｒａ：錨の把駐力係数
ｗａ：錨の水中重量［Ｎ］
ｒｃ：錨鎖の把駐力係数
ｗｃ：錨鎖の単位長さ当たりの水中重量［Ｎ/ｍ］
ｋ ：伸出錨鎖長さ［ｍ］
α ：錨鎖張力の上向き成分が錨の把駐力におよぼす影響を表す係数 The anchoring support method according to claim 1, characterized in that the limit holding force (T h * ) for each of the three states is derived based on equation (3) for the first state, equation (4) for the second state, and equations (5) to (8) for the third state.
ra : anchor holding power coefficient wa : underwater weight of anchor [N]
r c : Holding power coefficient of anchor cable w c : Underwater weight per unit length of anchor cable [N/m]
k: Length of extended anchor chain [m]
α: Coefficient expressing the effect of the upward component of the anchor cable tension on the holding power of the anchor
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