US1553160A - Boat - Google Patents

Description

Sept. 8. 1925. 1,553,160

} w. A. HICKMAN BOAT Fii d Sept. 25, 1924 1320022202": wiiz'ame/ifiz'ekfiiam,

Patented Sept. 8, 1925.

UNITED STATES PATENT OFFICE.

Boar.

Application filed September To all whom it may 'corwem:

Be it known that I, WILLIAM ALBnR'r' HICKMAN, a subject of the King of Great Britain, and a resident of New London, county of New London, State of Connecticut, have invented an Improvement in Boats, of which the following description, in con nection with the accompanying drawings, is a specification, like characters on the drawings representing like parts. I

. This invention relates to boats and more particularly to the propulsive systems thereof and the objectis to provide an improved and more efficient method of pro elling ves-' sels. The invention will be readily understood in view of the following description taken in connection with the accompanying drawings wherein:

Fig. 1 is a plan view of a boat shown for illustrative purposes exemplifying a form of the invention;

Fig. 2 is a quasi-diagrammatic view illustrating in side elevation the stern portion of the boat shown in Fig. 1; 7

Figs. 3 and 4 are similar views;

Fig. 5 is a stern elevation of the boat shown in Fig. 4; and

i Fig. 6 is a diagram to be referred to.

The system of boat propulsion herein described involves the use of a so-called surface or semi-submerged propeller wherein the shaft bearin and supporting struts and preferably a so the less efficient innermost portions of the blades are disposed above the surface. of the water in which the boat travels; This is usually effected by providp ing. a propeller on a shaft disposed arallel to and above the normal water line w en the boat is at speed, the blades of the propeller dipping into the water below the shaft as the shaft revolves. Such an arrangement of a propeller utilizing the direct propulsive eflect of the useful driving portions ofthe propeller blades, say the outermost twothirds of the lengt of the blades, and eliminating the retarding force of driving through the water those submerged parts which in the ordinary submerged screw propeller system are necesary for carrying the useful parts of the blades, to wit, the innermost; thirds of the blades, the hub of the propeller, the propeller shaft, bearings and struts, has demonstrated high. propulsive efficiency in boats ofwidely. varying t pes and particularly in boats running at hlgh 25,1924. Serial No. 739,837.

speed and, when driven by an engine of mechanism organized adjacent the center of the propeller which would cause retardation were not present, but such a construction is obviously an impossible abstraction. In the accompanying drawings I have illustrated b way of example merely a type of boat simi ar' to that shown in my Patent No. 1,204,355, dated Nov. 7, 1916, but not, however, because the scope of the invention is limited to that typeof hull. Onthe contrary, it is applicable to hulls of widely differing t pes and to relatively slow boats or boats 0 large displacement as will appear as the description proceeds. 4

Referring to-these drawings I have therein illustrated a boat having a hull 7 provided with an inverted V-shaped bottom, the V gradually flattening from forward to aft an merging adjacent the stern transom 11 in a flat or substantiall flat transom bot-- tom 13. The boat is a apted to be driven by a surface propeller 15 arranged on a proeller shaft 17 extending substantially parallel with the normal water line of the boat, this being the most efiicientangle for driving" the boat forwardly throu h the water as will be well "understood. (gbviously for constructional reasons, theshaft 17 is a certain distance above the bottom 13 of the stern transom and, if the propeller 15 were hung directly aft of the transom 11, only theoutermost portions of the blades would dip below the level of the bottom edge 13 thereof. i

A s eed boat of the type illustrated when travel ing tends gradually to rise toward the surface of the water as the speed increases owing to the structure of. the under-bpdy and at high speed there will be but sllght dis flac'ement by the hull andthe shaft 17 wi be raised correspondingly above the sur when the boat is at rest or moving at a moderate rate of speed. The water will flow out beneath the transom 11 leaving the bottom edge 13 thereof at a point considerably below 5 the normal level and curve upwardly toward and above the normal surface forming a wave as illustrated more or less diagrammatically by either of the lines L and H in- Fig. 2. The straight or relatively straight edge out the stern transom 11 is an example of a surface of a boats hull which delivers aft a sheet of water rising rearwardly in the form pf a wave.

The locatioribi the crest of the wave with respect to the transom 11 will vary in ac cordance with the speed of the boat and the height of the wave will vary in accordance with the boats displacement, the height of said wave as well. as the distance'of its crest from the transom being due to the inertia of the water. The form of the wave is susceptible of accurate calculation for any conditions. its height will vary ed 3nd practically fired for For example, the boat an hour, the water F cove the bottom line inches there inches one a h. inertia of the this height speed the in Figs. 2 and l have illustrated without any attempt dimensional accuracy a curve marked L representing the surface of ve this level. The i or course, regulate entirely upon the ill the water when the boat is running at a relatively low speed and a curve marked H representing the surface of the water when the boat is moving at a relatively high speed.

It will be obvious that if the propeller were hun directly aft of the transom 11 in Fig. 2 e total elfective area of the blades when the boat is in motion would be small because the shaft 17 is necessarily higher than the bottom line 13 of the transom and the propeller cuts the wave which is develo ed substantially at its trough. In ac-' cor ance with, my invention, therefore, the shaft 17 is so extended that the propeller 15 is hungat a substantial distance aft fromthe transom 11- of the boat to..-i ntersect the trough and in the vicinity of its crest so that the major portion of the effective surface of the propeller blade will cut through the water. Thus in Fig. 2 the propeller is shownjs so hung as to dip substantially cally decreased'by the dropping astern of the crest of the wave.

ln application to boats of very high speed this automatic regulation of the dip of the propeller may be of considerable advantage. In this instance the propeller may be placed very far behind the line 13, for instance,

six or seven feet, the crest of the wave in such coat being far astern. The surtace propeller intersecting this wave remote from its trough will have suihcient submerged area to permit the boat to be driven against its high resistance at a low speed while at eecis, when the resistance or the is low, of the propeller blade engaging tie water will be the minimum amount to drive the boat having in view the very relative inertias of the water at such speeds.

however, it were desired to provide 7* which would dip comparatively if" relatively high speed other (is, the wave close to its as shown. 1 3., y L siracle mor particularly in boats mod" Bi-114.1% speed or relatively great displacement, it will he seen from. inspection of 3 that this might submerg the of the proin the wave L generated at low speed and the surface propeller would then not function as such and there would be a great loss of eificiency at the low speeds'or when starting when the resistance of the boat'is greatest. To ermit the mounting of the propeller in sue a position as shown in Fig. 3 and to avoid thisdifiiculty I may utilize the construction shown in Figs. 4: and 5 where l have provided an extension from the planing surface of the boat 19 extending aft from the line 13 which develops the rearwardly rising wave, which surface prevents the rising of this wave in the line of the propeller shaft. Ateither side of the propeller shaft the surface 19 may merge into buttock portions 21 upwardly directed to permit the rising of the wave laterally adjacent the outer or active portions of the propeller blades. The

I ""19 is practically an extension aft of the otrising wave at a point remote from its" art tom of theboat and in thecase of a planing boat'must be looked upon as a portion of the actual planing area of the bottom and,

rich would be,

boat inany suitable manner and herein are shown as planes supported by struts 23 from the rear transom 11.

The operation of the construction shown in Figs. 4 and 5 will be readily understood and the preceding discussion made clearer by reference to Fi 6 illustrating diagrammatically a prope leras viewed from the rear. If line H represents the level of the water adjacent the lower edge of the transom 11, it will be clear that the propeller acting closely adjacent this transom the other portions of the propeller would dip into the water a relatively small portion of the blade. Suppose, however, the propeller to be hun further aft as shown in Fig. 3 and the hue 6-?) to. represent the height of water of wave H at the location of the propeller. It is clear from the figure that a much greater portion'of the propeller blade acts on the water. Now if a line 0--c represents the hei ht of the wave L at the same position, the ab of the propeller would normally be submerged with disadvantageous results. By virtue of the constructionof parts 19 and 21 as herein described, the wave is, as it were, divided and prevented from rising in the vicinity of the shaft and takes substantially the form indicated by the line d-aL-d. It is thus diverted from the hub and its bearings and which if submerge detract so much from its efiiciency while the outer portions of the blades, as will be clear from the diagrammatic figure, are operating in a depth of water rising to the line 0-0. Thus, in the position of the figure two blades are simultaneously efi'ective, whereas a single blade would be operatin if the height of water were at the level -b. As applied more particularly to boats of medium speed the arrangements described permit the use of surface propellers of re ativel .small diameter which nevertheless wil have the same or even greater absolute area submergedthan larger propellers mountedin the conventional position. This will permit engines of a given piston displacement to run efficiently at a higher number of revolutions per minute in hulls of a given weightand resistance. J f I have described certain specific appl cations of the principles of my invention whereby the same ma be put into practice.

7 formed to deliver aft a sheet 'of water rising;

It will be understoo thatthese exemplifications are for illustrative purposes only,

the scope of the invention being defined by the following claims.

Claims-- 1. A high speed motor boat having a hull as a wave governed by the inertia of the water and a surface or semi-submerged progllsr hung at such substantial distance aft m'said surface as to cut the wave remote spond with the increase in the relative inertia of the water at increased speeds.

2. A motor boat having a surface or semisubmerged pro eller, a hull having a surface forward of said propeller to develop a rearwardly rising wave, said propeller being hung aft of said surface to engage said wave, at a determined speed of the boat, at a substantial distance from the trough of said wave to permit maximum submergence of the effective portion of the blades. 4 l

3. A motor boat having a hullprovided with a surface to deliver a sheet of water aft rising as a wave governed'by the inertia of the water, a propeller. hung relatively far aft of said surface with its hub substantially at the same depth and means to prevent the rising of the wave in suchmanner as to submerge said hub while permitting such rising at the blades.

4. A motor boat having a surface or semi submerged propeller and having surfaces incorporated with the hull of the boat which are so shaped as to deliver rearwardly sep arated waves directed to the blades of the propeller away from the hub thereof.

5. .A boat having a hull having a bottom portion, a surface propeller hung aft of said bottom portion, a surface forward of said propeller to develop a flow of water and buttocks for guiding said fiow from said surface to the outer portions of the propeller blades.

6. A motor boat having a surface or semisubmerged propeller, a surface forward of said propeller to develop a wave rising rearwardly, said surface being continued aft along the center line of the propeller to prevent rising of the wave to submerge the hub thereof.

7. A motor boat having a surface propeller hung aft thereof at a substantial distance to engage the rising wave left astern by the boat as it advances at a point where its height substantially varies on changes of speed of the boat, whereby a decreasing dip is procured as the speed of the boat increases. r

8. In a motor boat, a surface propeller dis osed at a distance astern of said boat an having a maximum dip at a point substantially coincident with the crest of a wave produced by the inertia of a stream of water owing from beneath the boatwhen the latter istravelling at a given speed, said dip being automatically decreased as the speed of the boat increases and thecrest of said wave is moved astern by inertia of the water.

-9. A motorboatbomprising a hull, a sur'-" face propeller arranged at a substantial distance astern of said hull to effect a maximum submersion of said propeller at a given speed of the boat and means to direct the stream of water flowing aft from said hull into engagement with the more effective propulsive portions of said propeller.

10. A motor boat comprising a hull having a transom stern, and a surface propeller arranged aft of said transom in substantial spaced relation thereto, the blades of said propeller having a maximum degree of submersion when the boat is moving at a predetermined moderate speed and a vminimum degree of submersion when moving at top speed.

11. In a motor boat, a hull having a transom stern, and a surface propeller disposed aft of said transom substantially coincident with the crest of a wave produced by the boat when traveling at a given speed.

12. in a motor boat, a hull having a transom stern, a surface propeller arranged aft and in selected spaced relation to said transom and means to guide the stream of water flowing from beneath said transom to the propulsive areas of the blades of said proeller. p in a meter boat, a hull having a transom stern, a surface ropeller arranged aft and in selected space relation to said transom and means constituting a continuation of the bottom of said hull adapted to guide the stream of water from beneath said hull to the more effective propulsive areas of said propeller.

14. In a motor boat, a hull having a transom stern, asurface ropeller arranged aft and in selected spaced som and means constituting a continuation of the planing surface of said hull adapted to direct the stream of water flowing from beneath said hull to effective portions of the blades of said propeller, cutting said blades at opposite sides of the axis of said pro eller and in a plane substantiallyabove sai axis.

15. A motor boat having a surface propeller at the stern and a rearwardly extending plate underlying the shaft and extending adjacent to the propeller to intercept and break the wave of Water flowing aft from the bottom of the boat whereb to divert it from the central portion of t re propeller.

16. A motor boat having a surface propeller at the stern thereof adapted to en age the rising v1 ave of water in the wake of the boat and a water-break adjacent the shaft to divert the water from the central portion of the propeller.

In testimony whereo t it have signed my name to this specification.

WELLEIAM fitEKiRT MQKMAPL relation to said tran-

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