SE426465B - PRELIMINARY VESSELS - Google Patents

Description

15 20 25 30 35 8-003444-0 2 An uncertainty factor in most proposals also lies in the fact that the barges during transport, ie when the mother ship is under way, must be thought to be close to or partly also below sea level. "p None of the solutions now mentioned are favorable from a seaworthiness point of view. Barge trailers are of course extremely sensitive to rough seas and the same also applies to a large side cargo container and a hull with stern and stern ships composed of tankers or barge-bearing vessels with barges carried close The stresses on hooks and hydraulic locking devices on such vessels must be enormous, and barges have also been proposed where barges, after being lowered to the appropriate level, have been carried over decks through ports opened in the vessel. The barges are thus unwieldy and vulnerable and do not constitute an ideal solution. In addition, according to this proposal, the ship has not shown any satisfactory stability in the lowered position during loading and unloading of the barges, which appears to have been the most serious and unsolved problem with all known design proposals ..

A measure of a ship's stability is its height at the center, ie the distance between the ship's center of gravity and the intersection between the line of action of the displacement's imprint and the ship's plane of symmetry. This point - the ship's meta center - has a nearly unchanged position up to heeling angles of about 150.

The metacenter height depends on, among other things, the ship's center of gravity position and the moment of inertia of the waterline surface, so that a low center of gravity and a large moment of inertia give a large metacenter height, which, as long as the waterline surface intersects the ship's boarding, depends on water density.

The moment of inertia also decreases, as large free areas are present in the ship's tanks, which in turn reduces the size of the metacenter height. 10 15 20 25 30 35 8003444-0 3 A barge-carrying vessel, which during loading or unloading of barges has the main part of the hull under the loading deck filled with water, has hardly any other stability than that obtained from the fore and aft of the vessel . It has therefore been proposed to save a longitudinal tank along each of the ship's bottoms along each of the ship's types to be used as an air tank. However, it can be questioned whether air tanks in this position significantly contribute to the stability of the ship's submerged position.

The present invention intends to avoid the above-mentioned difficulties of barge-bearing vessels and consists essentially in that the ship's hull below the cargo deck is given in section a substantially trapezoidal shape, where the bottom of the vessel forms the shorter parallel side of the trapezoid, from which the trapezoidal hull's oblique surfaces extends on both sides slightly upwards, suitably up to the main deck.

Such boarding contributes to the ship's stability during ongoing immersion of the same and during ongoing emptying of the ballast tanks in connection with loading and unloading of barges.

A further improved stability is obtained by arranging, in connection with the sloping surfaces of the boarding at the deck closing, a substantially vertical double boarding, in which vertical ballast tanks are arranged, which may be terminated at the top with air tanks.

Alternatively, an existing hull with a rectangular hull in section can be given a trapezoidal shape by arranging on each table side a substantially entire underwater part of the board covering a triangular air tank section in section.

Such a hull provides stability both when loading and unloading barges and during walking. In addition, it exhibits relatively low propulsion resistance. The hull also does not require any sealing gates, as the cargo deck is high above sea level without contact with breaking sea.

Loading and unloading of the barges is then thought to take place in connection with loading and unloading ports, thereby lowering the parent vessel in calm water in a bay near the port, by filling the ballast tanks, so much that the barges will float over deck and can be laterally thrown out or winched in when unloading or loading, after which the mother ship, possibly after loading new barges, by pumping water out of the tanks, can be raised to normal freeboard height.

The proposal according to the invention is based on an in-depth analysis of the transport technology and the unloading and loading technology in port, especially when it comes to bulky goods, such as containers, trailers, cars and general cargo. The difficulties of entering large ports with large ship units and docking at the quay and the requirement for sophisticated loading and unloading devices have led inventors to the realization that the need is to have smaller ship units in port, while during transport between ports such large and sea worthy ship units as possible. These mutually incompatible requirements have led the inventor to the idea that one could be satisfied with a very incomplete utilization of the cargo capacity of a larger seaworthy vessel during transport, if one could thereby simplify and speed up cargo handling in ports. A closer examination has shown that, even if, as under the present proposal, only 20 - 30% of a larger ship's cargo capacity is utilized by distributing it on a plurality of cargo holds on deck, this means such a large gain in savings port dues, in that the parent vessel does not have to enter port, and in cargo handling costs by unloading and loading from or to barges at the quay, thereby largely compensating for the incomplete utilization of the parent vessel's cargo capacity during the voyage.

The invention is further apparent from the following description and the appended subclaims.

The invention will now be described in more detail in connection with the accompanying drawings. In this case, Figs. 1, 2, 4 and 5 show an embodiment of the invention, Figs. 3 and 6 show another embodiment and Fig. 7 a modification of the latter embodiment.

In this case, Fig. 5 is a section along the line V-V in Fig. 4 and Fig. 6 is a section along the line VI-VI in Fig. 3.

Fig. 7 is a similar section in a modified embodiment according to Fig. 3, where the ship is provided with vertical tanks, arranged on each side of the ship, formed by double-sided boarding.

As can be seen from Fig. 1, a barge-bearing vessel is obtained in principle by cutting off on an imaginary ship S with a forepeak F and a stern A about about one fifth of the hull volume under the deck between foreship F and stern A and dividing it into four elongated parts which are considered as barges P1, P2, P3 and P4. These barges, together with the cargo contained in them, are thought to be supported by a lowered but sufficient freeboard deck D on the ship.

The boarding is thought to have wing tanks V of the type shown in Fig. 5.

Unloading of the barges takes place in such a way that the entire hull of the mother ship is filled under the deck D, which is provided with tanks formed by longitudinal and transverse bulkheads. with water. In addition, ballast tanks are also filled in the bow and stern, so that the entire vessel is submerged at the level of the new deck D. In the foreship F and the stern A there is still carrying capacity, at least corresponding to the level of the fore and aft deck, which is assumed to be level deck. Additional water is filled into the ballast tanks in the bow and stern, until the barges are light and can be thrown out sideways from the deck.

- It is appropriate that tugs are available, which from a nearby port have already towed four new loaded barges, intended to replace those that have been unloaded. In this way, the mother ship S can unload its cargo in a few hours and take in new cargo and continue to the next destination, while the barges that have been unloaded are towed into port and can be unloaded in the proper order at the quay. 10 15 20 25 30 35 8003444-0 6 In connection with a practical embodiment of the invention, the realisability of such a seaworthy vessel shall be substantiated by figures. Such an embodiment is shown in Fig. 2.

According to the construction drawings, the vessel shown in Fig. 2 is thought to have a length of 330 m and a width of 40 m and a molded depth of 25 m, meaning a intended total cargo volume of 330,000 m3. However, if, according to the invention, the tire between the fore and aft spikes is lowered by 6 m to 19 m, the load volume is reduced by about 60,000 m3 to 270,000 m3.

Of these, 35,000 m3 are needed, 35,000 tonnes. For support of the four barges and for ballastäna mal åsterscar thus 235,000 m3. y In order for the barges to be able to float in over deck, the mother ship must be lowered further to a depth of 25 m, whereby the following displacement must be overcome.

In front and aft pike 80 x 30 x 6 = 14,400 tons.

For the fore aft bath 4 x 10 x s x äf- = 4080 to In addition, the center shots with 250 X (4 + 6) x 6 = = l5,000.

This gives a total of 33,480 tonnes.

These 33,480 tonnes are obtained as follows: l5,000 tonnes can, for example, consist of pig iron ballast and the rest of water ballast. v As soon as the barges have been winched over the deck and moored, the water ballast will be pumped out and the barges will rest on the deck.

After the ballast has been emptied from the most recently filled tanks, ballast water is also pumped out of the other tanks, until a draft of, for example, 11 m has been reached.

You then have the following situation: The ship is loaded with about 15,000 tons of pig iron and with four barges of a total of 60,000 tons. In addition, you have a ballast load in the tanks of about 60,000 tons. In addition, 8,000 tonnes of bunker oil. Together, this makes 143,000 tons.

There is thus a large quantity of ballast left to regulate the ship's draft and stability. in order to support the weight of the ship, which, in Fig. 2, the same designations have been used as in Fig. 1.

The barges have been fitted with a superstructure and have the designations P1, P2, P3, P4. The barge P3 is just being winched over the ship's deck D.

In the deck shown in the embodiment shown, a longitudinal center tank C has been arranged, which extends between the fore and aft pike and which thus forms a longitudinal, combined box beam and center tank of 6 x 4 in cross-section, and a center tank crossing a ramp, also the one with the dimensions 6 x 4 m. Both towards the ramp and towards the fore and aft pike, the deck is tilted upwards to be adapted to the front and aft inclination of the barges. Likewise, the four tire portions slope upwards towards the center tank, so that the front sides, which suitably for the sake of stability are inclined at a 45 ° angle, should be able to softly connect to said tank.

The boarding is also thought to have wing tanks of the type shown in Fig. 5.

Each of the four barges has a displacement of about 15,000 tons, a length of about 125 m and a width of 20 m and a draft of about 5 m and can carry about 8,000 tons of cargo.

A total of between 30,000 and 35,000 tonnes is thus transported, or together with the barges 60,000 tonnes by means of a vessel of approximately 200,000 tonnes dw with relatively little draft.

The center tank also serves as a walkway between the front and stern picks and to be able to fit winches and mooring bollards, etc.

Fig. 3 shows a barge-bearing vessel which has been designed with a trapezoidal board in section, which is inclined outwards.

In this case, a powerful center tank C has been constructed, which extends from the forepeak over the entire length of the ship to its transom. The center tank has been designed as a sturdy, whole-vessel-supporting structure, which also houses the shaft down to the engine room. Also in this case, the same designations have been used as in the previous figures.

However, here the boarding extends obliquely upwards past the deck and the barges are inserted not from the side but from the stern of the mother ship. Otherwise, this barge-carrying vessel operates in the same manner as those previously described.

It thus has a submerged position produced by water ballast, in which the water level extends about 6 m above the deck, thereby enabling the barges to be pulled into the gutters formed on the deck, and partly a level corresponding to the transport position, in which the mother ship has 8 - 10 m freeboard.

The proposed barge-bearing parent vessels and the barges adapted to them provide significant benefits: Firstly, a significant saving in freight costs is achieved by the consumption of bunker oil being significantly greater than that which would have been incurred for a vessel corresponding to a of the barges' load capacity and this largely also applies to the costs for the crew.

Secondly, you gain in loading and unloading time for the mother ships and at the same time also in port costs, in that the large mother ship does not have to enter the ports but can unload the barges in a quiet bay near the port of destination. Thirdly, in most ports, storage problems arise with the ever-increasing shipments of containers, trailers and cars. These problems can be partly solved by using the proposed barges, which can lie at the quay and be loaded directly with the loads when they come down to the port. The barges can thus be used as storage space.

Fourthly, it is gained that the barges can come to places with less draft to be loaded or unloaded there. 7 Fifth, it is easier to get a return load.

Sixth, combinations of different loads in different barges are possible. This makes the entire transport system more flexible.

Seventh, loading and unloading can take place during the day and thus enables a more even work rate for the stevedoring people. 1 Eighth, minor damage occurs to cargo, as loading and unloading takes place during the day and without agitation. Barge-bearing motor vessels according to the invention can be manufactured in a particularly advantageous manner according to the following guidelines.

It is known that ore and tank tonnage is extremely sensitive to fluctuations in the economy. During the current economic downturn, tank tonnage has been hit very hard and hundreds of tankers in the order of 80,000 to 350,000 tonnes are currently stored. The total set-up figure amounts to 48 million tonnes. In particular, vessels in the order of between 200,000 and 300,000 tonnes are badly damaged. The number of vessels of this size that are laid up is currently estimated to be well over 100. Through the now proposed method of building vessels according to the present invention, a large number of vessels in the order of 250,000 tons can be prepared for work.

The above-mentioned way of manufacturing barge-bearing vessels consists mainly in the fact that in the case of an already existing tanker a) the vessel's boarding between foreship and stern is reduced by 20 - 30% of the vessel's ground depth, either by deflecting the vessel's boarding as necessary. to the extent or by immersing the ship's deck by removing material and adding triangular air sections on the boarding, so that in both cases a substantially trapezoidal ship's hull is obtained, b) transforming part of the original deck between fore and aft pike into a center tank containing a supporting beam with a width of about 10% of the width of the tire, c) builds new tire parts and closes the tanks affected by the tire lowering, so that tire shelves or gutters for accommodating barges are formed on each side of the center beam.

Suitably, the side wing tanks are also provided with protection against breaking sea arranged in front and stern and the foresail is provided with a transversely extending protection.

In Fig. 4, a tanker of 330,000 m3 and 255,000 tonnes dw dw thus rebuilt has been illustrated. The designations are the same as in the previously treated figures. Of the former deck, a longitudinal beam C has been left, which forms a center tank between the fore and aft pegs and a perpendicular to this extending cross beam T, which also forms ballast tanks and also serves to stiffen the ship. .

For the four barges P1, P2, P3 and P4, of which P3 is not shown in the figure, deck shelves have been designed, in which the barges can be winched in, when the ship has been lowered to the level of its original deck. The wing tanks, of which only the port wing tank is shown in Fig. 4, have been denoted by V and are clearer from the cross section shown in Fig. 5 through the vessel. As can be seen, the wing tanks contribute to the stability in the vessel's completely submerged position, as the water level is the upper one shown in Fig. 5 and there is denoted by ÖN. When the ship is underway, the lower level NN applies and the wing tanks are then intended to protect the deck and the barges against breaking sea.

Below is a displacement calculation of the conversion of the tanker shown in Figures 4 and 5.

The deck has been lowered from 26 m to 20 m between the fore and aft piles, whereby the volume of the cargo tanks has been reduced from 330,000 m3 1-.111 2ss.ooo m3. 7 At a depth of 20 m, 255,000 tonnes can then be disposed of in the following way. bunker 5,000 tons of fore and aft pike -8,000 tons of ballast. 242,000 tonnes Total dw: 255,000 tonnes In this case, the center tanks in the center plane have not been used and the sludge tanks of 9,000 m have also been retained as reserves. On the other hand, you have to count on other ballast tanks 13,000 m3.

When the vessel is lowered for unloading to 26 m, the following extra displacement is obtained: fore and aft spike approx. 80 x 30 x 6 = 14,400 tons of center bulkheads approx. 250 x (4 x 6 + 6 x 6) = 15,000 tons of fore and aft beds approx. 4 x 10 x 4 x 50/2 = 4,000 tons of tire wings approx. 40/3 x 225 = 3,000 tons Sununa approx. 36,400 tons 10 15 20 25 30 35 8003444-0 ll These 36,400 tons are obtained as follows: old steel approx. = 3,400 tons extra steel , pig iron, ev. partial steel of the old tire 22,000 tons <-3oo0 m3) approx = 20,000 tons ballast tank as above approx = 13,000 tons Total approx. 36,400 tons For load under load the following figures are obtained: extra steel 22,000 tons barge 60,000 tons water ballast 60,000 tons bunker 8,000 tons Total approx. 150,000 tonnes The barges have a curb weight of 1500 to 2,000 tons and can carry a cargo of 9,000 to 10,000 tons and the barge of the barge vessel thus means that you have a volume-demanding cargo of 60,000 tons (together with the barges' curb weight) and that you operate a vessel of 250,000 tons with relatively little unloading, in that the draft is about 12 m towards the tanker's draft as tanks of 20 m.

In Fig. 6 it has been indicated how the rebuilding of the same tanks as just treated can take place to the supporting vessel shown in Fig. 3 with a trapezoidal hull in section. In this case, the tire is lowered instead of cutting off the board by cutting it off the frame and bending it out.

Fig. 7 shows the section of a barge-bearing vessel of the type shown in Fig. 3 with trapezoidal boarding seen in section leaning outwards. In this case, however, the center tank C has been replaced by the tank's upper sideboard forming tanks ST, which connect to the trapezoid in section trapezoidally outwardly sloping sideboard S and partly to the cargo deck D, the inner sideboard plate leaning against the deck parallel to the outboard's outboard. S to adapt to the side slope of the barge hull sides. Similarly, the deck D is moved upwards against a longitudinal center bulkhead L to be adapted to the lateral inclination of the corresponding barge hull sides. 8003-444-0 12 In this way, transport gutters are formed for the barges P1 and P2 and P4 and P3, respectively, in the longitudinal direction of the vessel, in which the barges, when the parent vessel is in the lowered position ÖN, can be winched.

Although the invention has been described in connection with some embodiments thereof, it may, however, be arbitrarily varied within the scope of the appended claims.

Claims (5)

10 15 20 25 30 8003444-0 PATENT REQUIREMENTS Barge-bearing vessels with an elongated hull shape and an open cargo deck intended to come below the water surface by filling the vessel's ballast tanks and lowering it, so that loaded barges can be made to float in over the deck and thereby either be thrown out during unloading or winched in during loading, characterized in that the hull (S) of the ship under the cargo deck (D) in section has a substantially trapezoidal shape, where the bottom of the ship coincides with the substantially shorter parallel side of the trapezoid, from which bottom the oblique side surfaces of the trapezoidal hull extend obliquely upwards to the cargo deck, between which and the bottom of the ship the ballast tanks are mainly located, whereby in order to stabilize the ship during the filling and emptying of the ballast tanks, a concentration of the ballast water near the lateral plane of the ship and the bottom is made possible. 2. A load-bearing vessel according to claim 1, characterized in that on each side of the ship's hull under the cargo deck (D) and closest to it, preferably by longitudinal bulkhead, a triangular air tank section or wing tank (V) is separated in the the upper part of the trapezoidal section, which wing tanks have a stabilizing effect on the ship's hull (S) in the lowered position. Barge-bearing vessel according to claim 1 or 2, characterized by a double board extending upwards from the cargo deck (D), on each side of the vessel, forming vertical ballast tanks (ST), the upper parts of which may be separated for use as air tanks. Barge-bearing vessels according to claim 2 or 3, characterized in that the trapezoidal hull in addition to the wing tanks separating the bulkheads has additional longitudinal bulkheads (L) which divide the hull (S) into a plurality of ballast tanks. Barge-bearing vessel according to claim 3, characterized in that the ship's double sideboard also contains shafts down to the engine room (M) as well as chimneys (SK) opening exhaust pipes for the engines, heating pipes or ventilation pipes. .