US2288490A

US2288490A - High-speed motorboat

Info

Publication number: US2288490A
Application number: US328171A
Authority: US
Inventors: Scott-Paine Hubert
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-03-25
Filing date: 1940-04-06
Publication date: 1942-06-30
Anticipated expiration: 1959-06-30

Description

June 30, 1942. H. SCOTT-PAINE HIGH-SPEED MOTORBOAT Filed April 6, 1940 3 Sheets-Sheet l wmme Nw m a m Q R R June 30, 1942, H.- Sco'rT-PArNE HIGH-SPEED MOTORBOA'I' Filed April 6, 1940 3 Sheets-Sheet 2 June 30,- 1942 H. sco'rr-PAmE 1 men-swan mowomsom Filed A rii s. 1940 3 Sheets-Sheet 3 INVENTOR. W Jm- ATTORNEYS;

Patented June 30, 1942 HIGH-SPEED MOTORBQAT Hubert Scott- Paine, Hythe, Southampton,

- England Application April 6, 1940, Serial No. 328,171 In Great Britain March 25, 1939 25 Claims. (01. 114- 665) This invention is for improvements in or relating to high-speed motor-boats and has for its object to provide new and improved constructions and arrangementsof such craft which are particularly suited for use as war vessels such, for example, as torpedo boats.

'One of the most desirable characteristics of sucdayes'sel is that it should be inconspicuous i as a target, and in general this is effected by -constructing-the vessel so that it has a low silhouette; but it is also essential that it should have good sea-keeping qualities in all weathers and also it should be'capable of high speeds even in rough seas, and this is attained by the novel hull lines hereinafter described.

Numerous attempts have been made in the past to provide hulls the main purpose of which,

was to reduce the resistance at high speed by making such hulls of a planing type so that the area of the wetted surface of the hull was rethe expense of introducing some of the inherent disadvantages of other types of hull.

The present invention has resulted in the provision of a surface or planning type of hull of the hard-chine type with novel characteristics giving improved performance as to manoeuvreability, steerability and seaworthiness at all speeds, and particularly at very high speeds, in comparison with any previously known type of hull, while maintaining at the same time the good qualities of a displacement hull at low speeds. More particularly stated, the invention I results in theprovision of a hull of the planing type which, by reason of the physical forces brought into'use, maintains its longitudinal and lateral stability throughout the speed range, that is, has minimum pitching and rolling irrespective of the direction of the sea; has such excellent directional stability that it does not yaw in-a following sea' to any objectionable extent; may

, be driven safely against a head'sea at higher speeds than has hitherto been consideredsafe:

and meinteins'thevariations of its longitudinal trim between very-narrow limitsthroughout the 5' According to mother feature of the invention,

tim

duced at speed by such planing motion. Some speed range; thereby improving the hull as a gun or torpedo firing platform and as a platform from which depth charges, mines and the like may be launched, and contributing to the general seaworthiness of the boat,and increasing the comfort and lessening the fatigue of the crew and passengers.

The hull lines which make possible the advantageous characteristics Just mentioned will be hereinafter described in detail, but the following features of the invention may be here mentioned. I

The most suitable type of vessel is the wellknown hard-chine type, and according to this lodnvention the sheer lines of the hull are such as to provide, with a continuous smoothly curved contour or deck-line, a high free-board forward and a low free-board aft. In the case of a torpedo boat, the after portionof low freevboard is of such a length as to provide adequate accommodation for a torpedo tube. The benefits obtained by this construction are:

(a) The extra buoyancy provided by the higher freeboard at the forward part of the vessel prevents it from diving or boring into waves when running at high speed, and improves the general seaworthiness of the vessel.

(b) The after portion of lower freeboard provides a torpedo launching platform which is sutliciently low and near the water level to facilitate the discharge of torpedoes, or if the vessel is used for other war-like purposes it provides a convenient platform for launching depth charges, mines and the like, and

(c) It is possible with this general construction of the hull to provide an adequately seaworthy boat having a very low silhouette and therefore inconspicuous as a target.

In practice it has been found that it is possible to provide a seaworthy boat as above described when the freeboard aft is about one-third to onehalf of the freeboard forward.

According to one feature of this invention the inconspicuousness of the boat which has a smoothly continuous deck-line is enhanced by so constructing the boat and its fittings that it presents a completely smooth and unbroken.

silhouette. This is effected by the omission of all parts such as masts, rigging, hatches, skylights, bollards, which present a broken and sharpedged silhouette, and further by shaping any outstanding parts, such as deck-houses, so that v theybrgaez-ge smoothly into the silhouette lines of the ' the camber of the forward part of the deck is her on the forward part of the deck enables the sight-line forward from the control-positions I of the craft, which are arranged somewhat forward of amidships, to be substantially lower than with a high cambered deck, without sacrificing the advantages above-mentioned of extra-buoyancy forward. I

According to yet another feature of the invention the centre-line of the deck immediately. adjacent the bow is sloped slightly downward, for the same purpose of giving a low sight-line forwardly from the control positions.

According to another feature of the invention, the sides of the boat are flared outwards towards the gunwale throughout their entire length.

- charge water therefrom, but the flattened cam-.

' Figure 2,

This flaring curvature "increases progressively from the transom tothe stem and the stem itself is flared forward to secure 'cdntinuitypfmieieature. The stem overhangs the forefoot consfd' erably, having in elevation a sloping S-shaped curve up to the deck. By this means onsiderable up-draught is created and a verydry deck is ensured and a good platform is provided for mooring operations and the like.

It will be appreciated that in view of the general requirement of a low silhouette for the craft, the control-positions which are normally situated in a super-structure or deck-house must also be kept-low, and it is for this purpose that the special constructions just mentioned for giving a low sight-line are provided, and according to another feature of the invention, the low silhouette and low height of the control-positions are obtained by constructing the vessel so that the maximum head-room available below the deck is not substantially greater than the height rofgig ga lifieonstruc ingtheriheekhouseavith One example of the'invention is shown in the 4 accompanying drawings in which:

Figure 1 is a side elevation of the boat,

Figure. 2 is a. plan view of the boat, Figure 3 a plan view of the boat with the deck removed, I I I Figures 4, 5 and 6 are outline. section on the lines i -4, 5-5 and 6-6 respectively of Figure ,7 is a side elevation showing the lines of the hull,

Figure 8 is a plan View the hull,

Figure 9 shows the transverse sections of the hull at the various stations indicated in Figure 8.

The vessel is of the hard-chine type consisting of a hull l0, deck 9 and wheel-house 12. The A boat isconstructed so that the sheer lines ll provide a high free-board forward 'and'a low, free-board aft with a continuous smoothly curved contour or deck-line, as is clearly seen in Figures 1 and 7. v

The vessel shown in the drawings is. of the; order of 70 ft. in length and the line indicated by showing the lines of .the reference in Figure 1 is the still water-- f lihe flhe free-board between this line and'the deck amorwardseniof the boat is about 8 5' ft. and at the aft .end about half this amount, and, in between, the sheer lines curve smoothly between these limits as may be seen from Figure 1. V I

The camber of the forward part of the deckis substantially less than that of the after part of the deck, and in this example the camber between the stem of the boat and thefpoint indicated by the reference 51 is about 10" on the full beam. This camber decreases uniformly from the point 58 up to the stem and near to the stein it is practically nothing, this change being illustrated by the camber 45 in Figure 5 and 44 in The vessel is constructed so that the. maxi- 4 its fiodr below deck level, but of substantially less 45 mum hea N vailable below the deck 9 is idth than the vessel so as to provide belowdeck cabin accommodation which whilst partlyof reduced head-room is also partly of the full available head-room. In this way it is possible to provide adequate cabin accommodation whilst I maintaining minimum overall height of the vessel. In so far as the cabin accommodation is concerned a sleeping berth or the like is preferably provided near the. floorlevel of the cabin in the space below the floor of the. wheel-house.

According to another feature of this invention, there is provided in a vessel as above described,

a wheel-house as described in my co-pending ap- I plication Ser. No. 328,170, now Patent No. 2,268,- 425, issued December 30, 1941.

According to yet another feature of this invention, additional armament for a craftas abovedescribed is provided by automatic gun-turrets of the enclosed type now used on aircraft, and I these are arranged so that access to the interior is obtained below deck level, so that they are accessible under any weather conditions.

. Preferably three such turrets are used, and ac- I cording to another feature of this invention one of these is disposed as far aft as possible and the other two are arranged one at each side of the after end ofthe wheel-house; in this way the maximum concentrationof fire in any direction, forward, aft or upwards is obtained.

wheel-house to be substantially lower than would be possible with a high'cambered deck without reducing the free-board forward and thesloping of the centre-line of the deck downward also: assists in giving a low sight-line forward from the controlpositions. I

The sides of the boat are flared outwards towards the gunwale throughout their entire length and this curvature increases progressively from the transom to the stein as may be seen from Figures 5, Gland 4 in which the flare at 48 in Figure 5 increases to the flare shown at 41 in Figure 4; all of which is shown more in detail in Figure 9. In addition, the stein itself is flared forward to securecontinuity of this feature. The stem overhangs the forefoot considerably having in elevation a sloping S-shaped curve up to the deck as indicated by the, reference 49 in Figure 1. 1

With the aid of the drawings, the novel hull lines to which the satisfactory performance of parent that said hull in transverse placement-length ratio, projected keel area and planing area have the following meanings:

Length-beam ratio is the length of the boat in feet divided by the beam of the boat in feet, at either the gunwale or the chine, that is,

B Displacement-length ratio is the displacement of the hull at rest in long tons divided by the cube of the ratio comprising the length in feet along the load water line divided by 100, that is Projected keel area is the area of the side elevation of any described under-water longitudinal elevational section through the centre line of the hull.

Planing area. means the area ofthat part of the bottom of the hull in contact with the water when the boat is supported mainly by the resultant force of forward speed and the longitudinal angle of incidence of said bottom, or the area available for such use, as the case may be.

The improved hull which is the subject of the present invention has a length-beam ratio substantially between 3.5 and 4.5, preferably ap-' proximately 3.5 to 3.9 at the gunwale and 4.1 to 4.5 at the chine. It has what are commonly known as a V bottom" and hard chines and it will be noted that said bottom has no steps and in transverse section has a dihedral angle on each side of the centre line throughout its length; and that said bottom sections are preferably concave in transverse section throughout the forebody, and are preferably concav or straight in cross section in the afterbody., The sides of the hull above the chines are preferably concave in cross section throughout their length and form stressed members which give most of the longitudinal strength to the hull. The distinctive knuckle or chine formed where the sides meet the bottom is a prominent feature throughout the length of the hull and does not merge at any point into either the sides or the bottom of the hull. The said chine in plan view, as will be obvious from Figures 8 and 9, has its maximum beam located well forward of amidships. The chines converge toward each other from the point of maximum beam to the stern of the boat, and the beam at the chine at the stern of the boat is preferably about 70% 'of the maximum beam at the chine, though my invention is not limitedto this ratio. It will also be noted from Figure 7 that the chines, in longitudinal side elevation,

are substantially straight from the stern throughout about of the over-all length of the hull; after which they curve upwardly to a slight extent which may be substantially between 6 inches and 12 inches in 40 feet; and that said chines in longitudinal side elevation from the stern throughout about of the over-all length of the hull have a relatively small angle to the load water line of the boat. It will also be ap section has an angle between the bottom and the sides, at and adjacent to the chine, which increases only slightly from the stem forward for about of the over-all length of the hull. It will also be apparent from Figures 4, 5, 6 and 9 that the sides of the hull in transverse section flare outwardly throughout the length of the hull and particularly in the forepart of the hull, so as to make the deck in plan similar in shape to the plan of the chines, but with somewhat greater beam and with somewhat greater length along the centre line,

i as best shown in Figure 8. As best shown in Figures 1 and 7, said hall in longitudinal elevation has a gunwale line characterized by considerable freeboard forward and a relatively lower stern, and with a peculiar sheer which generally may be described as having a convex curvein the forebody and a concave curve in the afterbody and as a whole having a mean angle of incidence to the horizontal or substantially between 2 and 10 depending on the length of the hull. The highest pointof the sheer of the gunwale and centre line is approximately 18% of l the over-all length of the hull from the bow. It is also a feature of my improved and unique hull that the section of greatest beam is always forward of amidships, and can be at a point between 25% and of the total over-all length of the hull measuring from the bow.

F01'ebody.In my unique hull, the area of the deck forward of the section of widest beam at the chine line, preferably greatly exceeds the area within the chine lines forward of the same section. The maximum beam at the chine is preferably about 80% of the maximum beam at the gunwale. Thev angle of intersection of the chine lines in plan at the stem post is preferably approximately 105, but my invention is not limited to this specific angle.

The aforesaid features provide for my hull a buoyancy in the forebody and an amount of planing areaat an optimum angle of incidence, which together make it impossible for the hull to dive and substantially impossible for the bottom of the afterbody to leave contact with the water. Another feature of my unique hull is that the projected keel area of the forebody is greater than the projected keel area of the afterbody (which latter may include that provided by the rudders and the propeller brackets) and the relations between these keel areas is substantially maintained throughout the speed range and in variations of sea conditions, this relationship being contributed to by the configuration of the chine line in longitudinal elevation as described, and the large planing area provided in the forebody; all of which combine to decrease yawing in a following sea to a very marked degree in comparison with previous hulls. Furthermore, the propeller and rudders are alway in solid water in a seaway. Tests have demonstrated that my unique hull form does in fact provide seaworthiness, manoeuverability, steerability and safety in a seaway at high speed, hitherto unobtainable with any other form of hull.

Afterbody.-It will be noted that the chine lines in the afterbody of myhull converge towards each other in the direction of the stem at a small angle substantially between 8 and 16". At no point in the afterbcdy do the chine lines or any of the water lines or the buttock lines have anyconcavity or reverse curvature, thereby allowing the water a fair flow aft from the point of widest beam of the hull, and insuring an adequate and fair flow of water to the propellers and rudders. It'is a. valuable characteristic of my hull that at any speed above approximately 15 knots littlevif any solid ,water washes the sides of the hull'above thechines, thereby preventing wide variations of projected keel area, particularly in the afterbody of the hull.

In planing types of hulls at speed, the lift provided by thepressure on the bottom, resulting from the forward speed and the angle of incidence of the bottom of the hull, to a very considrable ,degree takes the place of the support of displaced water; and it is a feature of my unique hull that the centre of pressure throughout its speed range is so close to the centre of ravity and moves only within such narrow limits that the longitudinal trim of the hull varies within very narrow limits throughout the speed range, approximately a maximum of 4.

Sides.--The sides of the hull flare outboard from the chine to the gunwale and are preferably I concave in transverse section throughout the length of the hull, such concavity being very pronounced at the bow and gradually reducing towards the stern, as will be apparent from Figs. 4, 5, 6 and 9. The angle formed between the sides and the bottom of the boat. adjacent the 6.5% of the over-all length of the hull, but this proportion may also diminish as the size of the vessel increases,

Bottom surfaces.--It has already been pointed out that, as shown in Figure 9, the bottom of the hull in cross-section is concave on each side of the centre line to the chines throughout the forebody, and from amidships the concavity decreases until the bottom sides are substantially flat near the stern. It will also be noted that the dihedral angles between the bottom sides and a, horizontal plane (or dead rise) are large angles at the forward end of'the hull, and that they decrease from the bow to approximately the section of maximum beam beyond which they decrease at a less rapid rate. Figure 9 illustrates these features. ihe characteristics of the bottom sides of the hull, in combination with the length-beam'ratio and the other described characteristics of the hull, result in causing the buoyancy of the hull to increase with increased immersion at a much higher rate than in any previous hulls. Moreover, the concave form of the bottom sides in transverse section in the forebody, and the absence of concavity or of reverse curvature ofthe water lines in plan and of the buttock lines in the afterbody, combine to re- A boat of the displacement type, or having certain displacement type characteristics, with or without forward speed and with headseas approaching, has-a time lag'in responding to the lift on the forebody providedby the added buoyancy as each wave in passing covers with solid water a larger volume of the hull; and this la encourages the boat, after the wave has passed the forebody and increases the buoyancy of the afterbody, to dive or plunge into the trough of the sea and subsequently into the next wave. Efiorts have been made to alleviate this by various means, but a hull, operating under displacement characteristics suffers from this inherent disadvantage. In the case of previous known planing types of hulls, driving at a headsea has been dangerous because of pounding and the risk I of the boat diving into a sea. With my improved hull, the tendency to dive .in a seaway is overcome by the coordination of its various characteristics including the described location of the greatest beam of the hull, the lengthbeam ratio as described, the provision of a substantial planing area in the forebody at an optimum angle of incidence as determined by the rise in the longitudinal elevation of the chine lines, I

and by the very large amount of buoyancy provided above the chine lines by the sides of the boat as described. Moreover, in my unique hull, those features contribute effectively to deterring the bottom of the afterbody frombreaking contact with the water in a seaway and also contribute to the control of the effective keel area of the hull.

In the case of a hull having displacement type characteristics, in a seaway with the seaeither ahead or following, the projected keel areas of the forebody and the afterbody are increased and decreased alternatelythrough wide limits, with the result that in the case of a following sea the stern may be pivoted around the bow or in' the case of a head-sea the bow may be pivoted around the stern though to a much lesser extent; these actions being commonly called yawing and broaching and being caused by the lack of control of the alternate changing of the effective projected keel areas of the forebody and afterbody. In my improved type of hull, the pro-- Jected keel areas of the forebody and afterbody are so disposed and controlled as described, that adequate efiective keel area is always maintained in the afterbody whilst in the foreboiv the maximum projected keel area islimited by the specific characteristics as described irrespective of the amount of rise given to the afterbody in passing over a wave or sea. It is also a characteristic of my improved hull that relative duce the amount of wetted surface of the hull and reduce the waves and wake created by the vessel. Furthermore, these forms of the bottom sections in cooperation with other features of the hull increase the righting forces and contribute to lateral stability of the hull at speed.

Balance of keel areaQ-Another feature of my unique hull which improves its seaworthiness,-

maneouverability and stability characteristics in a seaway is the disposition of the projected keel area. The problem of maintaining steady longitudinal trim when a high speed boat is being driven against wave formations heading toward it at angles forward of abeam, is a difficult one.

variations in the projected keel areas of the forebody and the afterbody are limited by the described form of the hull throughout its speed range. Tests have shown that this coordination and control of the projected keel area in the forebody and afterbody provides steering and maneouvering characteristics hitherto unobtainable.

Aerodynamic features-The sheer .of the gun-= wale of my improved hull in longitudinal elevation, and the longitudinal angle of incidence between the bottom of my hull and the water have been described so far in connection with their direct and indirect hydrostatic and hydrodynamic contributions to seaworthiness. These two features of my hull, however, offer additional advantages by bringing into action certain aero-, dynamic forces. The sheer of the gunwale, as

described herein and shown in the drawings, corresponds generally to the longitudinal elevation of the deck which is kept as free as possible from obstructions and superstructures so that the air-flow over the deck provides a negative pressure and therefore some aerodynamic lift. The sheer line of the gunwale from a position substantially between Va and A; of the length of the hull from the stem should be substantially horizontal or with a slight downward trend towards the stem, and the superstructures on the deck should be suitably streamlined as shown. The relatively small angle of'incidence of the bottom of my hull to the water line, the small dead-rise of the chine line in longitudinal elevation, and the low length-beam ratios all cooperate so that throughout the planing-speed range of the hull there is an air cushion between the bottom portion of the forebody and the water which contributes to the longitudinal stability of the boat and to the elimination or reduction of pounding.

Example of typical hulL-A hull typical of my invention, as shown in the drawings, has an over-all length of 70 feet,- a load water line length of about 64 feet, a maximum beam of approximately 15 feet, 3 inches at the chine and 19 feet, Binches at the zunwale, a beam at the stern of 9 feet, 9 inches at the chine and 11 feet, 8 inches at the gunwale, the maximum beam being located at approximately 40 feet from the stem. The chine in longitudinal elevation is at an angle to the load water line of approximately 2'/ at the stern, which increases to a tangential angle of approximately 6 at the bow. The greatest molded depth is about 9 feet, 9 inches and is preferably located at a position about 55 feet forward of the transom measured along the centre line. The molded depth at amidships is about 7 feet, inches, and at the transom is about 5 feet, 1 inch. The freeboard is approximately 8 feet at the point of greatest beam, and is approximately 3 feet, 6 inches at the stern. These dimensions, together with the lines illustrated in the drawings, provide the hull with a substantial well-faired sheer, which together with the described length-beam ratio, and the deck gunwale line in plan provide a configuration that gives the hull an aerodynamic lift. v

The centre of gravity of the boat should be located at a point about 26 feet 6 inches from the stern measured along the load water line. The displacement ofthe boat with the engines, but without the useful and consumable load, should be about 49,000 to 54,000 lbs. Such a hull has a normal fully loaded displacement of about 70,000 lbs. or 31 long tons; but can be loaded in excess of the normal displacement up to atotal displacement of about 80,000 lbs. or 36 long tons. Therefore, the displacement-length ratio of such a boat when loaded as mentioned ranges from about 120 to 140. Even when fully loaded, sucha hull is able to pass the hump" of the horse-power speed curve; which means that there is relatively little drop in top speed with said higher displacement as compared with the top speed with the normal displacement.

2,ses,4ao

Teses have shownv that my unique, hull possesses qualities of seaworthiness and manoeuverability superior to those of any previous 7 i. type hulls ofcomparative size and superior to those of many vessels of much larger size. it has been demonstrated that my hull will make a 90 fully stabilized turn to port or starboard at about "60 knots in approximately 8 seconds with a heel or bank inward of the turning circle; and will hold any course in a seaway with the sea in any direction relative to the course, without substantial tendency to yaw.

The wheel-house I2 is provided with a conning bridge as described in my copending patent application Serial No. 328,170, new Patent No. 2,268,425, issued December 30, 1941.

The conning bridge is constituted by a cockpit 62 which opens through the roof of the wheelhouse so as to provide a conning osition which commands the whole of the boat. The conning bridge is provided with a floor 52 which is above the level of the floor. I 4 of the wheel-house and scuppers 61 in the floor 52 leadoutside the wheel-house so that the cockpit can be cleared of water and although the conning bridge is left open, the water-tight closing of the wheel-house of the vessel is not impaired. Access to the conning bridge is attained from inside the wheelhouse by a watertight door 64 (Figure 3) and oral communication is established from the conning bridge with the coxswainstationed inside the wheel-house at by the opening 80, and with a chart room 63 aft of the conning bridge by the opening 6|. The openings may be provided with doors or windows and the conning bridge can thus be left open at the top without impairing the watertight closing of the whole vessel. The wheel-house can be entered directly by the hatch 12, Figure 2, which, however, is normally closed when under way.

The wheel-house occupies nearly half the length of the vessel and is arranged approximately in the middle of it. Three water-tight bulk-heads, l5, ii, "are provided below the deck-line and underneath the wheel-house. These bulk-heads divide the boat into a compartment 2i constituting the crews quarters, a compartment I 56 for officers accommodation and wireless, a compartment 22 which may contain fuel tanks, and a compartment 23 which constitutes the engine room in which three engines 24 are carried.

The full available head-room beneath the deck 9 is provided in the crews quarters 2| since the floor of the wheel-house terminates at the forward bulk-head 11. The wheel-house extends slightly further forward than this bulk-head and access to the crew's quarters is obtained from inside the wheel-house by the door 53 on the starboard side of the wheel-house forward of the cockpit.

The next compartment III has the floor 14 of the wheel-house .in it and sleeping berths are provided under the floor H in the part II (Figure 6) of reduced head-room. The width of the wheel-house I 2, however is less than half the width of the vessel, so that the remainder of the space beneath the parts la and 8b of the deck,

room up to the deck level, and the compartments so formed, indicated at I! and II in Figures 3 and 6, provide respectively accommodation for officers, and a wireless cabim Access to the come partments 51 and 50 is provided by

steps

54 and 55 at the aft end of these compartments.

The next compartment 22 between the bulkheads i5 and It has the floor ll of the wheelhouse in it and is occupied by fuel tanks and the like, and access to'the engine'room is obtained from the interior of the wheel-house by an'opening 56 formed partly in the bulk-head l5 and partly in a continuation of the deck extending from the bulkhead I I to an instrument panel 10 mountedin the aft part of the wheel-house.

Immediately behind the opening 56 is a soundproof bulk-head H. The aftpartlof the wheelhouse provides lighting and additional head-room in the engine room. A hatch I6 for access to the engine room directly from the after part of the deck may also be provided.

It ill be appreciated therefore that the wheel'- house serves the purpose of providing communication under cover. between the compartments 2 i 23'and I56 without it being necessary td go on to the deck of the boat or to provide doors in the water-tight bulk-heads l5, l6 and ii. Further, the inconspicuousness of the boat is enhanced by the streamlined wheel-house of low height, which,

, with the boat, presents a completely smooth and unbroken silhouette.

Protection from aircraft orgunfire may be'obtained by covering the wheel-house, or the forward part of it, with armour-plate, such protection extending aft at least as far as the after end of the conning bridge, which itself may be accommodation on the port and starboard sides of it.

The aft part of the vessel of low free-board is of sufficient length to provide accommodation for two torpedo-tubes 33, and torpedoes 34 are stored on the deckforward of these tubes.

Additional armament for the craft is provided by automatic gun-

turrets

30, 3!, 32. These are of the enclosed type now used on aircraft.

The turret 30 is disposed as far aft aspossible and access to it is obtained below deck level from the engine room 23; the other gun-turrets 3i, and 32 are arranged one on each side of the after end of the wheel-house and are accessible from the latter. By this arrangement of the guns the maximum concentration of fire is obtained in any direction. The two forward turrets 3i and 32 are preferably high enough to fire above the roof of the Wheel-house and each of them can therefore fire in any direction from directly aft, outboard, forward and across the boat until obstructed by the other turret, giving a horizontal range of nearly 270. Similarly, the after turret can fire in any direction from directly aft outboard on either-side and forward to the point where it is obstructed by the forward turrets,

giving a horizontal range of about 330. Additional bulk-heads l8 and E26 may be provided forward and an additional bulk-head 25 aft, and access'to the compartments formed by them is obtained by water-tight doorssuch as its and |2Ba (Figure 3);

It will be seen -therefore that a vessel constructed in accordance with this invention although very small as compared with ordinary torpedo boats, provides adequate accommodation for the ofi'icers and crew and carries adequate armament, and is well suited for high-speed work at sea, being eminently sea-worthy under all conditions of weather. The complete closure of the boat is an important factor for this purpose.

Finally, it may be emphasized that when used for war-like purposes, it is extremely advantageous that the boat should be to the highest degree, inconspicuous as a target and this is achieved, as above described, by the use of an unbroken or continuously curved silhouette; for

this purpose all parts which when in use project from the silhouette and present a broken sharp-edged silhouette such as the mast, bollard, towing post and so forth, are arranged to be housed below deck level when not in use. This arrangement also offers the subsidiary advantage of reducing wind resistance which is important in the case of high-speed boats.

I claim:

1. A sea-going boat hull of the hard chine type, capable of high-speed planing operation and having displacement characteristics of moderate resistance at low speeds, having the following characteristics which in combination contribute to improved longitudinal and lateral stability, improved seaworthiness, improved manoeuverability, reduction of wetted surface and high speeds: a length-beam ratio substantially between 3.5 and 4.5, the section of maximum beam being forward of amidships; bottoni -sides which in the forebody are concave in transverse cross-section, the angles of deadrise of said bottom-sides decreasing from the bow substantially throughout the length of the hull and being large at the fore part of the hull and small at the transom, top-sides flaring outwardly from the chines at the fore part of the hull, the chines in longitudinal elevation being substantially straight but with a gradual rise from the stern throughout about A; of the over-all length of the hull.

2. A boat hull according to claim 1, in which the length-beam ratio at the gunwale is about 3.6 and at the chine is about 4.2.

from the bow.

4. A boat hull according to claim 1, in which the maximum beam at-the chine is about of the maximum beam at the gunwale, and the beam at the chine at the stern is about 70% of the maximum beam at the chine.

5. A boat hull according to claim 1, in which the maximum freeboard is in the forebody and is about 8% to 12% of the over-all length of the hull, and the minimum freeboaid is at the stern and is aboutone-half the maximum freeboard.

6. A boat hull according to claim 1, in which the concavity of the bottom-sides extends throughout substantially the length of the hull.

7. A boat hull according to claim 1, in which in still water the angle of incidence to the water of the bottom portion as determined by the chine in longitudinal elevation is substantially between 2 and 10.

8. A boat hull according to claim '1; in which the concavity of the bottom sides extends sub: stantially throughout the length of the hull, and the angle of incidence to the water of the bottom portion as determined by the chines in longitudinal elevation is substantially between 2 and 10.

9. A boat hull according to claim 1, in which the top-sides flare outwardly substantially the top-sides are concave in cross-section and I moderate resistance about 8% to 12%"of hull, and the minimum freeboard is at the stern flare outwardly and the cave. 12. A boat hull according to claim 1,' in which the angle between the top-sides and the bottomsides at and adjacent to the chine varies from about 95 at the stem to about 115 at a point about 80% of the over-all length of the hull from the stern.

13. A boat hull according to claim 1, in which the chines converge from the section of greatest beam toward the stern.

14. A boat hull according to claim 1, in which the sheer lines of the deck the bow for a distance about 18% of the over-all length of the hull and then slope downwardly to the stern, whereby the flow of air longitudinally over the deck produces a lifting eilect on the hull.

15. A sea-going boat hull of the hardchine type, capable of high-speed planing operation and having displacement characteristics of at low speeds, having the following characteristics which in combination contribute to improved longitudinal and lateral stability. improved seaworthiness, improved manoeuverability, reduction of wetted surface and high speeds: a length-beam ratio substantially between 3.5 and mum beam being located about 25% to 45% of the over-all length of the hull'from the bow, bottom-sides which are concave in transverse bottom sides are concross-section throughout substantially the length of the hull, the angles of deadrise of said bottom-sides decreasing from the bow throughout the length of the hull and being large at the fore part of the hull and small at thetransom, topsides flaring outwardly throughout substantially the length of the hull, the flare of the top-sides being more pronounced at the fore part of the hull than at the after part, the chines converging from the section of greatest beam toward the stern and in longitudinal elevation being subslope upwardly from 7 and is about one-half the maximum freebcard.

19. A boat hullaccording to claim 15, in which in still water the angle of incidence to the water of the bottom portion as determined by the chine in longitudinal elevation is substantially between 2 and 10.

20. A boat hull according to claim 15, in which the concavity or the bottom sides extends substantially throughout the length of the hull. and the angle of incidence to the water of the bottom portion as determined by the chines in longitudinal elevation is substantially between 2 and 10.

21. A boat hull according to claim 15, in which the topsides are concave in cross-section throughout substantially the length of the hull;

22. A boat hull according to claim 15, in which throughout substantially the length of the hull the top-sides are concave in cross-section and 4.5, the section 01' maxistantially straight but with a gradual rise from i the stern throughout length of the hull.

16. A boat hull according. to claim 15, in which the length-beam ratio at the gunwaie is about 3.6 and at the chine is about 4.2.

17. A boat hull according to claim 15, in which about of the over-all the maximum beam 'at the chine is about 80% of the maximum beam at the beam at the chine at the maximum beam at the chine. I

18. A boat hull according to claim 15, in which the maximum freeboard is in the-forebody and is the over-all length of the gunwale, and the the stem is about 70% of the deck produces a all length of the hull and flare outwardly and the bottom sides arecconcave.

23. Aboat hull according toclaim 15, in which the angle between the top-sides and the bottomsides at and adjacent to the chine varies from about at the stem to about at a point about 80% of the over-all length of the hull from "the stern. k 24. A boat hull according to claim 15, in which the sheer lihesof the deck slope upwardly from the bow fora distance about 18% of the overthen slope downwardly to the stern whereby the flow of air longitudinallyover the deck produces alifting effect on the hull.

25. A boat hull according to claim 15, in which the maximum beam at the chine is about 80% of the maximum beam at the gunwale and the beam at the chine at the stem is about 70% of the maximum beam at the chine, the maximum freeboard is in the forebody and is about 8% to 12% of the oven-ail length of the hull, the mini mum freeboard is at the stern and is about onehalf the maximum freeboard, the concavity of the bottom-sides extends substantially throughout the length of the hull, and the cidence to the water of the bottom portion as determined by the chine in longitudinal elevation is substantially between 2 and 10, throughout substantially the length of the hull the topsides are concave'in cross-section and flareoutwardly and the bottom-sides are concave, and the sheer lines of the deck slope upwardly-from the bow for a distance about 18% of theover-all length of the hull'then slope downwardly to the stern, whereby the flow of air longitudinally over lifting eflect on the hull. HUBERT SCO'I'r-PAINE.

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