US2936728A - Ship construction for use with fin stabilizing arrangements - Google Patents

Description

May 17, 1960 BELL 2,936,728

SHIP CONSTRUCTION FDR USE WITH FIN STABILIZING ARRANGEMENTS Filed Dec. 17, 1956 mm Bell, 'Beckenham, England, assignor to Muirhead & Co. Limited, Beckenham', England Application December-17, 1956, Serial No. 628,653

Claims priority, application Great Britain December 22, 1955 1 Claim. (Cl. 114-126) This invention relates to the construction of ships which are to be stabilized against roll or pitch by the use of activated fins, that is, fins which project from the sides of the vessel and are tilted in either direction from a central, neutral position in order to impose a torque upon the vessel to oppose the undesired movement.

The general construction of activated fin installations for ships is of two known types. In one type the fins are retractable and may be withdrawn into the sides of the ship. In this construction water-tight boxes must be let into the ships sides and provision must be made for extending and retracting the fins. Thus the installation is quite elaborate and occupies a good deal of space inside the ship at the expense of that available for cargo or stores. The equipment is also heavy and costly.

The other type of stabilizer fin is not retractable and the gear is therefore smaller, lighter and cheaper. The disadvantage is that the projecting fins may foul jetties or other underwater structures and reduce the manoeuvreability of the vessel when not in action for stabilizing. This disadvantage may be reduced to a minimum by using small fins which do not extend beyond the bilge keel (if used) or are located within the angle formed by producing the substantially straight side and the substantially fiat bottom of the ship.

This requirement imposes a serious limitation on the size of the fin and to secure effective stabilization, the number of fins required may become excessive. Accordingly, the present invention has for its object to provide an improved design and construction of fin mounting and fin which enables a much larger fin to be employed without allowing the fin to project beyond the limits hereinbefore laid down. The invention consists of a ship construction for use with fin stabilizing arrangements in which local depressions are provided in the side of the vessel for mounting the stabilizing fins. This enables a greater width or outreach of fin to be used. The depressions may be formed by removing alength of the arcuate portion at the turn of the bilge and substituting, for example, a substantially flat plate so that in section it is in the form of a chord to the original arc.

The local depressions in the ships hull may be formed by plates which are substantially [flat where the fin is adjacent to them and the plates are faired ofi both forward and aft of the fin, to allow a smooth streamline flow of water past the hull and the fins.

Any type of fin may be employed with the invention, for example, a unitary fin of streamline form or a high efficiency type of articulated fin having one or more flaps which are tilted to greater angles than the body of the fin.

In order further to increase the efficiency of fin operation, additional fixed fins set in the direction of the stream line flow may be fitted either forward or both forward and astem of the activated fins in order to direct the flow of water to and/or from the activated fin in such a manner as will ensure maximum operating efliciency of the latter.

Ueied S es P w 2,936,728 Patented May 17, 1960 "ice . 'Iheinvention will be further described in conjunction with the accompanying drawings in which:

. and 15 at 23 and 23 Figure 1 shows a part section of the hull of a ship with a stabilizing fin.

Figure 2 shows a part section of the with a stabilizing fin and three fixed fins.

Fig. 3 is an underneath view of Fig. 2.

Referring to Figure 1, the substantially vertical side of the ships hull is shown at 11 and the substantially horizontal bottom at 12 and these are produced as dotted lines 13 and 14 respectively. The normal curve of the hull is shown at 15 but this portion has been removed locally and replaced by a flat portion 16. To avoid fouling jetties or other underwater obstructions the outreach of fin 17 is kept within the angle formed by lines 13 and 14. Fin 17 is attached to fin shaft 18 which is carried in a bearing contained in bracket 19 attached to hull plates 16.

Fin shaft 18 is coupled by suitable mechanism (not shown) to a power drive arranged to tilt fin 17 in either direction from the neutral position to provide the stabilizing torque. Such mechanism is well known in the art.

Figure 2 shows a section of a ships hull on the centre line A-A looking in the direction of arrow B and in this figure three fixed fins are shown in addition to the stabilizing fin 17 which, as in Figure 1, is carried on fin shaft 18 supported in a bearing bracket 19. In Figure 2, 15 and 15 show the unaltered curved portion of the hull corresponding to the portion 15 of Figure 1, whilst 16 corresponds to the fiat portion 16 of Figure 1. A fixed fin 21 is set forward of the stabilizing fin 17 and is so positioned that when stabilizing fin 17 is in the neutral position fin 21 is directly in line with it.

Forward of fin 21 and interlocking with it is a further fixed fin 22 which is at right-angles to fin 21 and is so shaped as to promote a smooth streamline flow of water into the depression in the hull at 16 The substantially fiat portion of 16 is smoothly faired into portions 15 and Fin 22 is attached to fin 21 and to the portion 23 of the hull by means of a support or supports 24, of streamlined form.

A further fixed fin 25, also set at right-angles to stabilizhull of a ship ing fin 17 and shaped to promote a smooth streamlined flow of water out of depression 16 is attached to the hull by streamlined supports 26 and 27.

It will be understood that a single fixed fin 22 could be used on its own or the composite arrangement consisting of fixed fins 21 and 22 could be used without fin 25.

It will be evident that the use of larger fins is made possible by the depressions according to the invention without these projecting beyond the limits hereinbefore laid down. I

As an example of the improvement afforded by the invention, a fin width of 18 inches would be permissible with an 18-inch bilge keel; but by the construction according to the invention, the width of the fin may be increased to 2 ft. 6 inches and since the length of the fin may be increased in the same ratio the eifective fin area is made 2.8 times as great. In this way the number of fins required to provide a given degree of stabilization is very largely reduced.

The plate for closing the depressions, the activated fin together with any fixed fins and the operating mechanism, as well as an outboard bearing for the activated fin, if desired, may be formed as a unitary structure which may be inserted in the side of the ship either in construction or as a modification after removal of the necessary plates;

Various modifications may be made within the scope of the invention.

I claim:

A ships hull having a substantially vertical side, a substantially horizontal bottom, a curved portion in between, a depression in the curved portions of the hullof form such that the streamline water flow along the hull Will flow smoothly into, through and out of the depression, an adjustable stabilizer fin mounted on the hull within the depression so as to be subjected to the streamline water flow therethrough and thereby exert its stabilizing effect on the hull and at least 'one fixed fin With axis at right angles to the axis of the adjustable stabilizer fin mounted on the hull to promote streamlined water flow through the depression.

References Cited in the file of this patent UNITED STATES PATENTS

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