DE102020117875A1 - watercraft - Google Patents

Abstract

The invention relates to a watercraft (100) which has a support element (1, 1'), in particular in the form of a support platform or a support frame (1.1, 1.1') for carrying a load, a buoyancy generator (2) for generating a force on the watercraft ( 100) acting buoyancy force, and an internal or external propulsion drive (3) for moving the watercraft along a direction of travel (10), wherein the buoyancy generator (2) is a temporary buoyancy generator (2). The invention also relates to a method for operating a watercraft (100).

Description

I. Field of application

The invention relates to a watercraft with a carrying element for carrying a load, a buoyancy generator for generating a buoyancy force acting on the watercraft, and an internal or external propulsion drive for moving the watercraft along a direction of travel. The invention also relates to a method for operating such a watercraft.

II. Technical background

Generic watercraft are known from the prior art, which can be used to carry a load, for example containers or the like, and can be driven either by means of an internal drive system, ie a drive system attached to the watercraft itself, or an external drive system. Drive, ie a driving drive attached to another watercraft or the like, which can be connected to the watercraft, are driven.

Such watercraft can be used, for example, to transport containers or other goods across rivers or other bodies of water. However, it should already be pointed out at this point that although the invention will be partially described below using an example for the transport of containers, no restrictions of any kind can be derived from this.

In order to provide a buoyancy force acting on the watercraft, watercraft of the generic type also include a buoyancy generator. If the watercraft is a support platform, for example a pontoon or a work platform, such buoyancy generators can be designed as floating bodies in the form of air chambers, which can be arranged below the support platform.

The floating bodies can be made of aluminum, for example, which means that they are characterized by a high degree of rigidity, but compared to floating bodies made of plastic, especially in chemically polluted waters, they can be very susceptible to pitting and the associated leaks and other damage, unless particularly so expensive aluminum alloys are used.

In addition, such floating bodies have a relatively high driving resistance during locomotion, especially if they are designed to absorb high loads and to ensure a sufficiently high stability against capsizing, so that the internal or external driving drive must be dimensioned relatively strong and/or only comparatively low driving speeds can be achieved.

III. Presentation of the invention

a) Technical task

It is therefore the object of the invention to provide a watercraft of the type mentioned at the outset and a method for operating such a watercraft which has a reduced driving resistance compared to known watercraft in connection with high reliability and at the same time is also suitable for transporting heavy loads.

b) Solution of the task

According to the invention, this object is achieved by a watercraft according to claim 1 and a method according to claim 16 . Advantageous embodiments emerge from the dependent claims.

With regard to the watercraft, the object is achieved in that the buoyancy generator is a temporary buoyancy generator.

The term "temporary buoyancy generator" is to be interpreted in connection with the present invention in such a way that the buoyancy generator is designed in such a way that it generates the buoyancy force temporarily, i.e. not permanently. Compared to permanent buoyancy generators, such as buoyancy bodies, this results in the advantage that the buoyancy generator can only generate buoyancy when it is actually needed. Also, according to the invention—in contrast to permanent buoyancy generators—the density of the temporary buoyancy generator, preferably of the entire watercraft, does not necessarily have to be lower than the density of water.

If the watercraft according to the invention is used, for example, to transport a load that is itself buoyant, the buoyancy generator can be designed in such a way that it does not generate any buoyancy when the watercraft is stationary, but it does so when the watercraft is moving along the direction of travel The buoyancy that acts causes the load to be transported to be only partially or not at all submerged in the water. As a result, a by the driving drive of the watercraft overcoming driving resistance can be reduced along the direction of travel.

The propulsion drive can be designed as an internal propulsion drive, ie a propulsion drive attached to the watercraft itself, or as an external propulsion drive, which is only assigned to the watercraft and operatively connected to it, but is not part of the watercraft . The external drive can be part of another watercraft, which is coupled to the watercraft and serves as a towing watercraft.

In order to generate the buoyancy force that supports the watercraft, the temporary buoyancy generator can comprise at least one flow control element, which has an angle of attack in relation to the direction of flow and/or which has such a cross-sectional profile that when there is a flow against the flow control element along the direction of flow, the lift force is generated. If the watercraft includes such a flow guidance element, the buoyant force is only generated when the watercraft is moved by means of the internal or external drive, i.e. has a driving speed greater than zero. In this case, the external or internal drive is to be considered functionally as part of the temporary lift generator.

According to one embodiment, the at least one flow guide element can comprise at least one flow guide plate, which has an angle of attack with respect to an inflow direction, which is preferably adjustable. The inflow direction is a direction that is essentially opposite to the direction of travel of the watercraft. The flow guide plate preferably has a profile which essentially corresponds to a flat plate, so that it does not generate any lift when aligned essentially parallel to the direction of travel, i.e. when there is no angle of attack. It is only through the angle of attack that a water flow impinging on the at least one flow control plate is deflected during the movement of the watercraft on the water surface along the direction of travel, resulting in a buoyancy force acting on the watercraft. The angle of attack is to be selected in accordance with the load to be carried, since on the one hand it must be selected sufficiently high that the necessary lift force can be achieved, but on the other hand it should only be selected as high as necessary, since with increasing angle of attack a through the flow guide -Plate generated deceleration effect and thus the driving resistance of the watercraft increases.

In order to be able to generate the buoyancy force similar to that of a hydrofoil boat and preferably to be able to move the watercraft including the load absorbed thereon relative to the water surface with particularly little friction, it can additionally or alternatively be provided that the at least one flow control element has at least one flow control wing covered with an airfoil. Preferably, the flow guide vane can also have an angle of attack that can be adjusted in relation to the direction of flow, in order to be able to adjust the lift force in the desired manner. The airfoil profile is preferably designed in such a way that the buoyancy force causes the watercraft, including the support element and the load carried thereon, to be lifted relative to the water surface when a predetermined speed is reached in the direction of travel. In order to achieve a particularly low driving resistance, after reaching the predetermined driving speed along the direction of travel, preferably only the flow guide vane and/or optionally the support element can be immersed in the water or slide on the water surface.

If the watercraft according to the invention includes the at least one flow guidance element, it is also advantageous that an effective area of the at least one flow guidance element is dimensioned in such a way that it corresponds to more than 10%, preferably more than 50%, of a base area of the support element. As a result of this, a high lift force can be achieved even at comparatively low driving speeds along the direction of travel.

In order to be able to generate sufficient buoyancy when the watercraft is at a standstill, i.e. in a state in which the watercraft is not moving or is only moving slightly, it is proposed according to a further exemplary embodiment of the invention that the temporary buoyancy generator be a fluid jet delivery unit, in particular a A water jet delivery unit or an air jet delivery unit which is set up to deliver a fluid jet directed away from the support element, in particular downwards, the fluid jet delivery unit preferably having a pump, for example an impeller pump. The fluid jet delivery unit is preferably also mounted on the watercraft such that it can be pivoted about a pivot axis running essentially parallel to a transverse direction of the watercraft, so that a delivery direction of the fluid jet can be adjusted. Additionally or alternatively, the fluid jet delivery unit can also be pivotable about an axis that is essentially parallel to the vertical. This can also Direction of travel of the watercraft are influenced.

In order to provide the propulsion force that propels the watercraft in the direction of travel, the internal or external propulsion system is mainly provided, which is preferably in the form of a propeller propulsion drive or in the form of a fluid jet propulsion drive, preferably a water jet propulsion drive or an air jet propulsion drive, can be formed.

If the watercraft includes the internal propulsion drive, this can be arranged on or in the support element to achieve a compact design of the watercraft and to ensure a low center of gravity for the watercraft.

If the temporary buoyancy generator is designed as a pivotable fluid jet delivery unit as described above, this can, however, also act as a driving drive, depending on the pivot angle set.

In addition, it is conceivable to provide a plurality of fluid jet delivery units, in which case a predetermined first number of the plurality of fluid jet delivery units can be used to generate the buoyancy force, while a predetermined second number of the plurality of fluid jet delivery units can be used to generate the driving Driving force can be used along the direction of travel.

In order to be able to ensure sufficient loading space for transporting the load, for example one or more containers, and good access for loading and unloading the watercraft, it is proposed according to one embodiment that the support element is plate-shaped, for example in the form of a support platform.

If a weight-saving and compact design of the support element is to be achieved, the support element can additionally or alternatively comprise a frame. In order to implement a particularly compact embodiment, it is also conceivable to integrate the lift generator, in particular over a large area, into the frame.

Furthermore, depending on the size and shape of the load to be transported, the carrying element can be essentially polygonal, preferably rectangular, or essentially circular or essentially elliptical in plan view.

In order to be able to ensure a particularly high rigidity of the support element, so that only slight twisting of the support element occurs even in strong waves, the support element can, according to one embodiment, be made at least partially from a substantially rigid material. This can prove particularly advantageous in the case of loads to be transported, which themselves would react very sensitively to possible twisting.

However, if instead it is to be ensured that the load to be transported is only influenced as little as possible by the occurring waves, the carrying element can alternatively be made at least partially from a substantially elastic material. As a result, the support element can compensate for the influence of the waves by local deformations that follow the waves that occur, and consequently increased security against swinging and possible tipping of the support element together with the load to be transported can be achieved.

In order to also be able to transport a large number of individual loads to be transported at the same time, the watercraft can also comprise a plurality of carrying elements, which are preferably lined up in the direction of travel and/or essentially transversely to the direction of travel. In addition, this can also be helpful for transporting loads which, although they have relatively large dimensions, are only light in weight, so that selective support and a comparatively low buoyancy force are sufficient. As a result, a particularly low driving resistance can consequently be achieved.

In order to ensure a secure connection of the individual support elements, the majority of the support elements are preferably coupled to one another, in particular detachably, by essentially rigid coupling elements.

It should also be added that the support element for taking up the load can comprise a plurality of supports which are supported at one end on the support element or on a part connected thereto and at the other end take up the load, the supports preferably being telescopic and/or spring-loaded. If the supports are designed to be telescopic, the distance between the load and the support element can be adjusted depending on the situation. If it is preferred to keep the load away from waves potentially occurring on the water surface, a correspondingly increased distance can be set, while a small distance can be advantageous to ensure a low center of gravity of the watercraft.

With regard to the method, the object is achieved in that the watercraft is lowered into the water and a buoyancy force acting temporarily on the watercraft is generated.

It should already be pointed out at this point that all the advantages and effects explained with regard to the watercraft according to the invention also apply to the method according to the invention.

The temporary buoyant force can be generated by moving the watercraft along a direction of travel, in particular by means of a flow control element, for example a flow control wing with an airfoil profile and/or at least one flow control plate. The buoyancy force generated by the movement can preferably be regulated, in particular by adjusting an angle of attack of the flow guide element.

In addition or as an alternative, it is conceivable to generate the temporary buoyancy force while the watercraft is at a standstill, in particular by means of a fluid jet delivery unit. This is particularly advantageous when the load to be transported is not itself buoyant.

Depending on the type and extent of the load to be transported, this can be placed on the watercraft before or after the watercraft is launched. For example, if the load itself is buoyant and is to be used to provide the buoyancy force while the watercraft is stationary, it can be advantageous to place the load on the support element before the watercraft is launched. If the temporary buoyancy force is already generated on the water surface while the watercraft is stationary, the load can also only be placed on the support element after the watercraft has been launched.

character list

• 1a: eine Seitenansicht eines erfindungsgemäßen Wasserfahrzeugs gemäß einer Ausführungsform,
• 1b: eine Vorderansicht des erfindungsgemäßen Wasserfahrzeugs,
• 1c: eine Aufsicht auf das erfindungsgemäße Wasserfahrzeug,
• 2a: eine Seitenansicht einer ersten Ausführungsform eines temporären Auftriebserzeugers für das erfindungsgemäße Wasserfahrzeug,
• 2b: eine Seitenansicht einer zweiten Ausführungsform des temporären Auftriebserzeugers für das erfindungsgemäße Wasserfahrzeug
• 2c: eine Seitenansicht einer dritten Ausführungsform des temporären Auftriebserzeugers für das erfindungsgemäße Wasserfahrzeug,
• 3: eine Aufsicht auf das erfindungsgemäße Wasserfahrzeug, welches um ein weiteres Tragelement ergänzt ist,
• 4a und 4b: jeweils eine Seitenansicht einer Abwandlung der ersten Ausführungsform des temporären Auftriebserzeugers.

Embodiments according to the invention are described in more detail below by way of example. Show it:

• 1a : a side view of a watercraft according to the invention according to one embodiment,
• 1b : a front view of the watercraft according to the invention,
• 1c : a view of the watercraft according to the invention,
• 2a : a side view of a first embodiment of a temporary buoyancy generator for the watercraft according to the invention,
• 2 B : a side view of a second embodiment of the temporary buoyancy generator for the watercraft according to the invention
• 2c : a side view of a third embodiment of the temporary buoyancy generator for the watercraft according to the invention,
• 3 : a top view of the watercraft according to the invention, which is supplemented by a further support element,
• 4a and 4b : each a side view of a modification of the first embodiment of the temporary lift generator.

In 1a a watercraft according to the invention is generally denoted by 100 .

The watercraft 100 according to the invention comprises a support element 1, which has a support frame 1.1 in the illustrated embodiment. A load L to be carried is supported on the support frame 1.1 via a front support 1.2, lateral supports 1.3 and a rear support 1.4. The supports 1.2, 1.3 and 1.4 can preferably be designed to be telescopic and/or spring-loaded. The load L to be carried is formed from a control section Ls and a section L _B to be loaded, which is loaded with containers Lc in the illustrated embodiment. The control section Ls can be provided to accommodate a person (not shown) steering the watercraft 100 and can have corresponding control devices, also not shown in detail, which are used to control the operation of the watercraft 100 and the temporary lift generators 2 and a propulsion drive 3 of the watercraft 100 are provided.

Vessel 100 is in 1a shown in a state in which it is floating on a water surface W, with the supporting frame 1.1 and a part of each of the front support 1.2, the side supports 1.3 and the rear support 1.4 being below the water surface W, and the load L being completely above the water surface W is located. As a result of this, a particularly low driving resistance can be achieved by the sliding of the support frame 1.1 on the water surface W, with only wave peaks occurring during the journey being cut.

As in 1b , the front view of the watercraft 100, the support frame 1.1 in the illustrated embodiment has a profile shape with recesses 1.1a formed in the direction of the vertical 12. The provision of the depressions 1.1a provides sufficient installation space for a compact arrangement of one or more 1b not shown, to allow temporary lift generator 2, which with reference to the 2a , 2 B and 2c to be discribed.

2a shows a first embodiment of a temporary lift generator 2, which is designed as a flow guide plate 2a. The flow guide plate 2a is attached to the support frame 1.1 so that it can _{pivot about a pivot axis S a that is} essentially parallel to a transverse direction 11 2a only a section is shown. In order to generate a buoyancy force acting on the support frame 1.1 and thus on the entire watercraft 100 in a direction essentially parallel to the vertical 12, the flow guide plate 2a has an angle of attack α _a in relation to an inflow direction 10', which is at an angle to the direction of travel 10 of the watercraft 100 is the opposite direction. The angle of attack α _a is preferably defined by an in 2a not shown actuator adjustable, which can be designed for example as a mechanically or electromechanically operated actuator.

2 B shows, however, a second embodiment of the lift generator 2, which is designed as a flow guide wing 2b with an airfoil profile. The airfoil profile of the flow guide wing 2b is designed in such a way that when the flow approaches the flow guide wing 2b along the direction of flow 10′, analogously to the flow guide wing 2a according to FIG 2a , a buoyancy force acting on the support frame 1.1 and thus on the watercraft 100 is generated. The flow guide vane 2b can also be pivotable _{about a pivot axis S b} to regulate an angle of attack α _b and thus the lift force, preferably also by a mechanically or electromechanically driven actuator.

2c finally shows a third embodiment of the lift generator 2, which is designed as a water jet delivery unit 2c. Analogous to the embodiments according to 2a and 2 B the water jet delivery unit 2c is also attached to the support frame 1.1 so that it can be pivoted _{about a pivot axis S c .} If the water jet delivery unit 2c is in an alignment that is essentially parallel to the vertical 12, when a pump (not shown) driving the water jet delivery unit 2c is operated, a water jet is delivered downwards, so that a jet of water also hits the support frame 1.1 and thus the watercraft 100 is generated in a direction essentially parallel to the vertical 11 acting upwards. This alignment is preferably present when the watercraft 100 is stationary. By regulating an angle of attack α _c in the direction of a direction essentially parallel to the direction of travel 10, in addition to the buoyant force, a propulsion force driving the watercraft 100 in the direction of travel 10 can be generated, so that the watercraft 100, similar to the principle of a vertical launcher, travel can record. In the embodiment shown, the water jet delivery unit 2c can consequently also be used as a traction drive 3 .

1c finally shows a top view of the watercraft 100 according to FIG 1a and 1b .

As in 1c recognizable, the watercraft 100 comprises a plurality of water jet delivery units 2c, which can also be used as a propulsion drive 3. As in 1c It can also be seen that the water jet delivery units 2c in the illustrated embodiment can also be _{pivoted about a pivot axis S v} running essentially parallel to the vertical 12 in order to be able to rotate the watercraft 100 about the vertical 12 and thus correct the direction of travel 10.

In addition to the water jet delivery units 2c, several lift generators arranged in a row in the form of flow guide plates 2a and/or flow guide vanes 2b are also provided, so that a comparatively high lift force can be generated even at low speeds along the direction of travel 10.

3 10 is a plan view of the inventive watercraft 100 according to FIG 1c , which is supplemented by a further supporting element 1' with a further supporting frame 1.1', on which a further load L' with further containers L _{C' is} placed. The support element 1 ′ can essentially correspond to the support element 1 , but in contrast to the support element 1 tapering to a point in the direction of travel 10 , it has a substantially rectangular shape. To generate a buoyancy force acting on the supporting element 1', one or more buoyancy generators 2a and/or 2b and/or 2c according to FIGS 2a , 2 B and 2c be provided. The support frame 1.1' is detachably connected to the support frame 1.1 via preferably rigid coupling elements 4, so that the travel drive 3 attached to the support frame 1.1 can be used as an external travel drive for the support element 1'.

As in 3 indicated only schematically, the watercraft 100 can also be supplemented by more than one additional support element L', ie, depending on the design of the traction drive 3, any number of support elements can be lined up. Is a If particularly high drive power or particularly precise maneuverability is required, it is also conceivable to couple several watercraft 100 to one another.

the 4a and 4b finally show a modification of the first embodiment of the temporary lift generator 2a Wherein a flow directing plate are each attached 2a at a front end in the direction of travel 10 of the support frame 1.1 and a further flow directing plate 2a at a rear end in the direction of travel of the support frame about a pivot axis S 1.1 _A pivotable. It should be noted, however, that if desired only one flow guide plate, ie either only the flow guide plate 2a at the front end of the support frame 1.1 or only the further flow guide plate 2a at the rear end of the support frame 1.1 can be provided.

the 4a shows a state in which the flow guide plates 2a have the _{above-described angle of attack α a} relative to the inflow direction 10'. If a lift force is generated by a flow against the flow guide plates 2a along the direction of flow 10', the support frame 1.1 can also assume a driving angle of attack α _{F in} relation to that of the direction of flow 10', which is preferably smaller than the angle of attack α _a , as in 4b shown.

Once the support frame 1.1. has reached the driving angle of attack α _F with respect to the direction of flow 10', the angle of attack α _{a of} the flow guide plates 2a can therefore be reduced to a value which is preferably selected in such a way that the flow guide plates 2a are aligned parallel to the support frame 1.1 . As a result of this, both the flow guide plates 2a and the support frame 1.1 can assume the driving angle of attack α _F with respect to the flow direction 10' and therefore act together as the flow guide elements 2a and 2a1 with a correspondingly enlarged effective area.

It should also be added that the watercraft 100 can, if desired, also, preferably completely, submerge below the water surface W by means of appropriate control of the flow control plates 2a and then move forward like a submarine. In the same way, the watercraft 100 can be brought to the surface by appropriately opposing activation of the flow guide plates 2a. In addition or as an alternative, the immersion of the watercraft 100 while traveling above the water surface W can, if desired, achieve a strong deceleration effect in order to brake the watercraft 100 .

Reference List

1.

Carrying element, carrying platform

1.1.

supporting frame

1.2.

front support bracket

1.3.

side support

1.4.

rear support bracket

1'

another supporting element

1.1'

another support frame

1.3'

additional lateral support

2

lift generator

2a

baffle plate

2 B

flow control vane

2c

fluid jet dispenser, water jet dispenser

3

Drive, water jet drive

4

coupling element

10

driving direction

10'

flow direction

11

transverse direction

12

vertical

S

pivot axis

sat

pivot axis

Sb

pivot axis

sc

pivot axis

Sv

pivot axis

SA

pivot axis

aa

angle of attack

ab

angle of attack

αc

angle of attack

α v

angle of attack

αF

driving angle of attack

100

watercraft

L

load

L'

another load

LC

Container

LC'

more containers

LB

section to be loaded

LS

control section

W

water surface

Claims (19)

Watercraft (100), with - a carrying element (1,1') for carrying a load (L, L'), - a buoyancy generator (2) for generating a buoyancy force acting on the watercraft (100), and - an internal or external one Propulsion drive (3) for moving the watercraft (100) along a direction of travel (10), which can be part of the buoyancy generator (2), characterized in that the buoyancy generator (2) is a temporary buoyancy generator (2). (Wing) watercraft after claim 1 , characterized in that the temporary lift generator (2) comprises at least one flow guide element (2a; 2b) which has an angle of incidence (α _a , α _b ) with respect to an inflow direction (10') and/or which has such a cross section - Profile has that the buoyancy force is generated when the flow directing element (2a; 2b) flows along the flow direction (10'). watercraft after claim 1 or 2 , characterized in that the at least one flow guide element (2a) has at least one flow guide plate (2a) which has the angle of attack (α _a ) in relation to the direction of flow (10'), which is preferably adjustable. watercraft after claim 2 or 3 , characterized in that the at least one flow guide element (2a) comprises at least one flow guide wing (2b) with an airfoil profile which preferably has an adjustable angle of attack (α _b ) in relation to the direction of flow (10'). Watercraft after one of Claims 1 until 4 , characterized in that an effective area of the at least one flow guide element (2a; 2b) is dimensioned such that it corresponds to more than 10%, preferably more than 50%, of a base area of the support element (1). (Beam) Watercraft according to one of the preceding claims, characterized in that the temporary buoyancy generator (2) comprises a fluid jet delivery unit (2c), in particular a water jet delivery unit or an air jet delivery unit, which is set up to project a , in particular downwards, directed fluid jet and, wherein the fluid jet delivery unit (2c) preferably has a pump, for example an impeller pump. Watercraft according to one of the preceding claims, characterized in that the internal or external drive (3) in the form of a propeller drive or in the form of a fluid jet drive, preferably a water jet drive (3) or an air jet drive is formed. Watercraft according to one of the preceding claims, characterized in that the internal drive (3) is arranged on or in the carrying element (1, 1'). Watercraft according to one of the preceding claims, characterized in that the carrying element (1, 1') is plate-shaped, for example in the form of a carrying platform, and/or comprises a frame (1.1). Watercraft according to one of the preceding claims, characterized in that the carrying element (1, 1') is essentially polygonal, preferably rectangular, or essentially circular or essentially elliptical in plan view. Watercraft according to one of the preceding claims, characterized in that the support element (1, 1') is at least partially made of a substantially rigid material. Watercraft after one of Claims 1 until 10 , characterized in that the support element (1, 1 ') is at least partially made of a substantially elastic material. Watercraft according to one of the preceding claims, characterized in that the watercraft (100) comprises a plurality of support elements (1, 1'), which are preferably lined up in the direction of travel (10) and/or essentially transversely to the direction of travel (10). watercraft after Claim 13 , characterized in that the majority of the supporting elements (1, 1') are coupled to one another by essentially rigid coupling elements (4). Watercraft according to one of the preceding claims, characterized in that the support element (1) comprises a plurality of supports (1.2, 1.3, 1.4), which at one end on the support element (1) or with this ver support the connected part and take up the load (L, L') at the other end, the plurality of supports (1.2, 1.3, 1.4) preferably being designed to be telescopic and/or spring-loaded. Method for operating a watercraft (100), in particular according to one of the preceding claims, characterized in that - the watercraft (100) is lowered into the water, and - a buoyancy force temporarily acting on the watercraft (100) is generated. procedure after Claim 16 , characterized in that the temporary buoyant force is generated by moving the watercraft (100) along a direction of travel (10), in particular by means of a flow guide element (2a; 2b), for example a flow guide wing (2b) with an airfoil profile and/ or at least one flow guide plate (2a). Method according to one of the preceding method claims, characterized in that the temporary buoyant force is generated while the watercraft (100) is stationary, in particular by means of a fluid jet delivery unit (2c). Method according to one of the preceding method claims, characterized in that before or after the watercraft (100) is launched, a load (L) is placed on the watercraft (100).

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