US2234899A

US2234899A - Air cushioned boat hull

Info

Publication number: US2234899A
Application number: US299892A
Authority: US
Inventors: Andrew J Higgins
Original assignee: HIGGINS IND Inc
Current assignee: HIGGINS IND Inc; HIGGINS INDUSTRIES Inc
Priority date: 1939-10-17
Filing date: 1939-10-17
Publication date: 1941-03-11
Anticipated expiration: 1958-03-11

Description

theatre i Weldon hour a aeration at i 1 one.

dppiicatioii @etoher ll, i939, Serial No; t99,iitft 5 (Git-tilin "this invention relates to Movement in hoot hull eonrtruetion particularlg applieahle to a hull oi the eovered in mg Watent lilo. hl itlll, granted January 1?, will.

*lliie hull has loroud spoon shaped how cape-l hie oi enguiling the aerated water ehurned up log the forefoot so that the vessel rides largeig upon air hulohles. it has a deadrise or w sheped hottorn, haclr oi the lorefoot so that the huhhles m eontinuailg travel up the inclined surleew oi the hottom oi the hull and escape at the ehine, which term as used herein refers to the line or angle oi junction hetween the bottom and sides, the purpose losing to prevent the aerated water liow== gg lug into the path oi the propeller, and the hull has a longitudinal semi-tunnel oi progressive-lg increasing arose-section, beginning git oi that portion oi the hull oi maximum beam into which tunnel the upper part of the propeller extends,

go the ohiect oi the tunnel being to are up how the depths below the hoat, through the vaeuum produced log forward-movement oi the hull, the column oi solid iuriaerated) water against which the propeller thrusts, avoiding cavitation.

5 The ohlect oi the present invention is the provision oi longitudinal ribs or rails located in strategic positions on the bottom oi the hull and accomplishing the lollowins "results:

(a) lo deflect inwardly the spray which go dashes against the how of .the boat go that it will he entrained beneath the hull and not pushed aside hr the displacement of the hull;

(h) To prevent the aerated water thus engulfed, irom going straight back into the path at oi the propeller;

(cl To prevent the sldewise escape of the aerated water until it reaches the middle oi the hull;

(d) To permit the lateral escape of the aerated 4 g water in the midship region of the hull;

ie) To prevent the aerated water which has escaped at the mids'hip section, from being drawn haclr under the quarters and into the path of the propeller by the vacuum created in the after n region by the passage of the boat through the water, i

Uther obiects oi the invention will appear 'as the following description of a preferred and prac-' tical embodiment thereof proceeds,

50 in the drawing throughout the several figures oi which the same characters of reference denote identical parts:

Figure l is a side elevation of a boat hull emhodying the principles of the present invention:

g Figure 2 is a bottom plan view: a p

(ml lid-66.5)

Figure l is a trout and view; and

Figures 4 and 5 are sections taken; respectively, along the lines d-i and 5-45 oi higure in Referring now in detail to the several hes,

the numeral i represents in general the hull -which has a broad transverse how log t, which gives the tread spoon shape to the overhanging portion i oi the how. The how overhang is slight lg and smoothly curved at its juncture with the how log t, the curvature gradually merging into m a deadrlse or ll-shape. Figure 3. shows that ad iacent the water line the if-shape at the how is foot and of dissipating the most of the air irom gg the water before it reaches the tunnelled portion of the hull; The bubbles continually rise along the inclined planes of the V-bottom toward the chines, so that the propeller reacts against a Toody of solid, that is to say. unaerated water. go

It happens, however, that at high speeds the hull may overrun the aerated water to such an extent that some of it will reach the propeller, causing more or less cavitation, and thus putting a limit tothe maximum speed.

The present invention provides an outer pair oi rails i and 8 at the forward part of the hull, the front ends 9 and ID of said rails converging toward the keel line well above the water line on the overhanging portion of the how. The g rails I and 8 diverge with a smooth curvature so that their rear portions II and I! lie adjacent and preferably parallel to the chines. The rear ends it and ll of these rails terminate in the mldship region of the hull. M

The function of the forward portions of the rails 1 and 8 is to catch the frothy portion of the. wave which slides up against the bow, and which. ordinarily would be dashed laterally in the form of spray, and to tuck it under the forefoot, au'ggg menting the volume ofaerated water upon which the boat hull glides. The rear or under water portions of these rails function to confine the aerated water-beneath the forward part of the hullso that practically none of it will be lost or before it reaches the midship region of the boat.

Inside of the outer pair of rails I and 8 is an inner pair [5 and I6 which, like the outer pair, converge from the opposite sides of the keel. The inner pair of rails, however, diverge at a much smaller angle than the outer pair, and have their rear portions extending along the hull intermediate-the keel and the outer pair, and being fairly close to the keel. The object of this inner pair of rails is to exclude the aerated water from that area of the hull which they encompass, so as to prevent aerated water from flowing back into the propeller stream. Thus, it may be stated that the aerated water is confined to that portion of the hull between the inner and outer pairs of rails. The inner pair of rails, as shown, likewise terminates adjacent the midship region of the boat.

The rails I, 8, l5 and [6 may be designated as cushion rails, for they define between them an area in which the hull is supported or cushioned on the aerated body of water.

A pair of rails l1 and i8 are positioned along the bottom of the hull at the quarters, preferably arranged along the chine lines on opposite sides and extending from the stern to a point approaching the midship region of the hull, leaving gaps l9 and 20 of considerable width between the outer rails I and 8 and the rails i1 and 18. This gap occurs where the pitch of the V-bottom is steepest, and the object of this gap is to provide an avenue for the escape of the aerated water from beneath the hull. This area of the v-bottom intermediate the forward and rear guide rails constitutes an unimpeded discharge area. The rear portions of the inner rails I5 and It materially assist in directing the aerated water toward these gaps. Thus, all of the aerated water is discharged from beneath the hull anterior to the region of the semi-tunnel 6.

It is, of course, a matter of elemental knowl edge that the narrowing portion of any boat hull rearward of the part of greatest cross-section induces a vacuum beneath and behind the boat, and if it were not for the rails l1 and I8 this vacuum would draw in beneath the rear portion of the hull at least some of the aerated water which has been expelled through the gaps i9 and 20. The function of the rear rails l1 and I8, therefore, is to keep this aerated water from returning and mixing with the water in which gardless of the speed at which the boat is driven,

thus materially advancing the maximum speed limit. a

The shape of the air cushion rails and of the rear rails, which may be termed solid water concentration rails, is a matter of option with the boat designer and builder, but I prefer to give them a stream-line shape, as shown, so that they will oppose the minimum of resistance to the forward movement of the boat.

While I have in the above description disclosed what I believe to be a preferred and practical embodiment of my invention, it will be understood that the system of rails as shown and described is applicable as well to hulls capable of entraining aerated-water atthe forefoot and discharging it at the midship region, even though the semi-tunnel feature may not be employed.

What I claim as my invention is:

1. In a power boat hull having a broad, sub- 2,as4,e9e

stantially flat bow overhang and forefoot, and

of v-bottom shape aft of said forefoot, a pair of deflecting rails projecting downward from the bottom of the hull, arranged symmetricallywith respect to the longitudinal central line on opposite sides thereof, having their forward ends adjacent the bow above the water line, and their rear portions adjacent the chines and terminating adjacent the midship region at the part of the bottom having the most pronounced V-shape,

' for guiding the aerated water churned up by the forefoot to a course in which it will be engulfed by the forefoot and its lateral escape prevented until it reaches the midship region, the sharply inclined planes of the hull immediately aft of said rails being unimpeded to permit said aerated water to escape laterally beyond the rear ends of said rails.

2. Ina power boat hull as claimed in claim 1, the rear portions of said rails being substantially parallel to the chines and lying closely adjacent thereto.

3. In a power boat hull having a broad, substantially fiat bow overhang and forefoot, and of V-bottom shape aft of said forefoot, a plurality of pairs of deflecting rails projecting downwardly from the bottom of the hull, arranged symmetrically with respect to the longitudinal central line, the forward ends of the rails of each pair being adjacent the keel line, the forward ends of the outer'pair being above the water line, the outer pair of rails diverging from the keel line toward the chines and having their rearward portions substantially parallel to the chines, lying closely adjacent thereto and terminating adjacent the midship region of the hull, the inner pair of rails diverging from the keel line and extending intermediately between the keel and chines, said inner and outer pairs of rails defining'between them a course for guiding the aerated water beneath the forefoot and along the forward portion of thebottom of the hull, excluding that region between the rails of the inner pair, the outer pair preventing the lateral escape of the aerated water until it reaches the midship region of the hull, the inclined planes of the hull bottom immediately aft of said rails being unimpeded to permit the aerated waterto escape laterally beyond the rear ends of said rails. 1

4. In a propeller driven power boat hull having a broad, substantially flat bow overhang and forefoot, and of V-bottom shape aft of said forefoot, a forward pair of deflecting rails projecting downwardly from the bottom of the hull, arranged symmetrically with respect to the longitudinal central line on opposite sides thereof, the forward ends of the rails being adjacent the keel line, adjacent the bow above the water line. and their rear portions adjacent the chines, and terminating adjacent the midship region, for guiding the aerated water churned up by the forefoot to a course in which it will be engulfed by the forefoot and its lateral escape prevented until it reaches the midship region, and a rearward pair of rails projecting downwardly from the bottom of the hull on opposite sides, substantially at the chine lines along the quarters, from points adjacent the stem to points rearward of said forward rails, leaving longitudinal unimpeded gaps between said forward and rearward rails in the area of the V-bottom, the aerated water rlsthus laterally diverted aerated water from bein inducted under the rear portion of the hull and into the propeller path by the vacuum incident to the forward movement of the hull.

5. In a propeller driven power boat hull having a broad, substantially fiat bow overhang and forefoot, and of V-bottom shape aft of said forefoot, a plurality of forward pairs of deflecting rails p ojecting downwardly from the bottom of the hull, arranged symmetrically with respect to .the keel longitudinal central line, the forward thereto and terminating adjacent the midship i region of the hull, the inner pair of rails diverging from the keel line and extending intermediately between the keel and chines, said inner and outer pairs of rails defining between them a course for guiding the aerated water beneath the forefoot and along the forward portion of between the rails of the inner pair, the outer pair preventing the lateral escape of the aerated water until it reaches the midship region of the hull, and a rearward pair of rails projecting downwardly from the bottom of the hull on opposite sides substantially at the chine lines along the quarters from points adjacent the stern to points rearward of said outer pair of forward rails, leaving unimpeded longitudinal gaps between said outer pair of forward rails a rearward rails in that section of the hullof the sharpest V-bottom, the aerated water rising laterally along the inclined planes of the hull being P permitted to escape laterally by way of said gaps, said rearward rails preventing the thus laterally diverted aerated water from being inducted un der the rear portion of the hull and into the propeller path by the vacuum incident to the forward movement of the hull.

ANDREW J. HIGGINS.

said