FI111616B - Hull Construction - Google Patents

Description

The present invention relates to a ship hull structure having a central main hull and two lateral hulls on each side of the main hull.

111616

Ship hull structure

Ships, cargo on board a ship at sea, crew and passengers are all prone to some kind of movement and acceleration. There are e.g. high risk of losing foot hold at an angle of 15 *, which poses a risk of working outdoors eg on an open deck. Another critical limit is the horizontal acceleration of about 0.2 g, where the movable objects on the ship's tables and shelves 15 fall to the floor. Vertical g-loads as low as 0.05 g significantly increase the risk of marine disease.

The relationship between the cargo units on board and the cargo platforms shall be taken into account that they are subject to mass forces during acceleration. These mass forces in turn cause strain on the ropes and cargo securing equipment.

25 With regard to frame structures, it can generally be stated that, when subjected to cyclic stresses, their lifetime depends on the correct dimensioning of • material fatigue. High quality and high strength materials have not proven to be advantageous in allowing 30 cycles of stress concentration to occur, resulting in high load / stress concentrations. In high waves, for example, the ship 's hull is forced to travel. under high acceleration forces, which often lead to high stress concentrations, regardless of whether the body 35 is made very rigid or flexible. Thus, the lifetime of the ship is determined by the fatigue stress in use. In strong waves, these stresses may be due in part to the load on board, but mainly to the g-forces acting directly on the hull 111616 2. Thus, it is desirable to design the hull of the ship so that the ship's hull is subjected to minimal g-forces, especially when traveling in strong waves. Even when driving in a roller-coaster, high cyclic stresses can be transferred to the hull, which means that the design of the bow and its load-bearing capacity are particularly important. Rolling tendency is also important with respect to the expected stresses on the ship's cargo and its ropes 10. The length-to-width ratio, the quality of the cargo, the position of the cargo on or in the hull, the quality of the water in which the ship will move are all factors that must be taken into account when determining the optimal design for each hull.

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The main object of the invention is to provide a hull structure which is very advantageous because it avoids the transfer of acceleration force to the hull and also to the cargo, also at relatively high speeds in high waves, and in addition to being less prone to rolling compared to conventional hull structures. The advantageous features of the structure also apply to the acceleration forces which operate horizontally, which is essential for safety and comfort on board.

25 • *

Another object of the invention is to provide a frame structure which allows high travel speeds with reasonable power consumption.

The objects are achieved by a frame structure that meets the requirements of the claims.

By using a trimaran structure, i.e., a central hull and side hulls, each of which has a freeboard with a limited height of 35 and is opened at least part of its length, the accelerating forces transmitted to the hull of the ship are reduced. This is accomplished by "ringing" or "rolling" the waves through the open portions of the hulls. Thus, most of the waves are trapped in the space between the deck, main body, and side hulls without causing any significant acceleration lift.

With most of the load bearing on the main body while the front portions of the side bodies are located at the bow wave coming from the main body, there is a very advantageous condition for designing the hull lines in an optimum manner. By choosing a bow with a main body bulb, the curvature angle and carrying capacity suitably trimaran has the ability to travel in strong waves without the risk of the bow trying to dig. Although the partial opening of the main body 15 is limited, its total carrying capacity is high due to the relatively long lever arm between the bow and the ship's axis of engagement.

By making the inner sides of the side frames substantially straight and parallel to the longitudinal axis of the ship, the interaction between the head frame and the side frames will be less.

Thus, the invention enables the construction of a lightweight hull for trimaran, which produces very moderate wind acceleration forces when traveling in high waves.

The invention will now be explained with reference to the accompanying drawings 30, in which:

Fig. 1 is a schematic perspective view of a hull structure according to the present invention used on a container ship of 150 to 35 m in length and 40 m in width,

Figure 2 is a schematic longitudinal section through the center of the vessel of Figure 1, showing the basic shape of the center hull and its position relative to the cargo deck;

Figure 3 is a plan view showing the relative position of the center frame and the side-5 frames, as well as the bow wave from the biscuit frame,

Figure 4 is a comparison of the horizontal and vertical acceleration forces in a conventional ship and in the hull structure 10 of the invention.

Figure 1 is a schematic perspective view of a hull structure according to the present invention used on a container ship 150 m long and 40 m wide. The central hull 1 is illustrated with a bulb 1a. The side frame 2 is provided with a hole 4 like a middle frame.

The opening 3 of the center frame 1 is best illustrated in Figure 2, where this frame is also shown with a higher hinge capacity at the front, while the load capacity of each side frame is moved far from the bow of the ship. This is more clearly illustrated in Figure 3. Figure 2 shows the height H above the freeboard of the center frame, which in this case is about 4 m. Thus, there is a large amount of empty space between the cargo deck, ie the waves • ♦ < .

Fig. 3 is a plan view showing the relative position of the center frame and the two side frames 2a and 2b. The side frames 2 are thus located 30 relative to the bow wave 5 so that the bow of each side frame, gon, will be behind the bow wave. This means that the side frames 2 will be on the trough, which reduces the resistance of the side frames during passage. The inner sides of the side frames 2, i.e. the sides facing the center frame, are preferably straight, and the spacing between the side frames and the main body is selectable depending on the shape and size of the body.

5, 111616

Figures 4a and 4b show the distribution of acceleration stresses affecting the shell on board when traveling in high waves, first in a conventional ship 5 in Figure 4a and then in Figure 4g, corresponding to a ship with a trimaran hull in accordance with the structure of the present invention.

The invention is not limited to the embodiments described above, but may be modified within the scope of the appended claims.

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Claims (2)

111616 6 1. Skrovkonstruktion med et centralt interesudskrov (1) ooh 20 vÄderskaterad placerade interesoskskrovet placerade sidoskrov (2), lumbar spine (1) och sido-skrovens (2) fribord är genombrutna (4) utmed en väsent-lig del av sin längd, you att vägor kan roll genome det utrymme som bildas mellan skrov och däck. 25 A ship hull structure having a central main body (1) and two lateral hulls (2) on each side of the main hull, characterized in that the free edges of the main hull (1) and the lateral hulls (2) are substantially open so that the waves are able to creep through the space 10 formed between the frames and the cover. Ship hull structure according to Claim 1, characterized in that the main hull (1) has 50 to 85% of the total carrying capacity, and that 50 to 15% of the carrying capacity is divided into two side hulls (2). 2. The loading device 1, the turn-off device (1) has a 50 to 85% total release rate, and 50 to 15% of the deploading capacity of the link load (2). 30