Boat hull having an upwardly arched bottom
US 2735392 A
Description (OCR text may contain errors)
Feb. 21, 1956 E. w. cox 2,735,392
BOAT HULL HAVING AN UPWARDLY ARCHED BOTTOM Filed DEC. 10, 1952 2 Sheets-Sheet l I I 'l I I N I I y ya JNVENTOR.
Earl W. Cox I Flg I Feb. 21, 1956 w, cox 2,735,392
BOAT HULL HAVING AN UPWARDLY ARCHED BOTTOM Filed Dec. 10, 1952 2 Sheets-Sheet 2 JNVENTOR. E0 rI W. Cox
477'OZNEYJ rearward flow in the BOAT HULL HAVING AN UPWARDLY ARCHED BOTTOM Earl W. Cox, Seattle, Wash. Application December 10, 1952, Serial No. 325,051
3 Claims. (Cl. 11462) This invention relates to improvements in boats and has reference more particularly to improvements in the details of construction of the hulls of propeller driven boats. More specifically stated, the present invention pertains, first, to the design or shape of the water engaging surfaces of a boats hull, and to the shape and relationship to each other of its water displacing portions.
It is one of the principal objects of this invention to provide a boat hull embodying novel features of design whereby water resistance to travel is reduced and faster speed made possible with the same or even a reduced power input.
It is a further object of the invention to provide a boat hull that is characterized by the provision in its bottom and substantially to its full length of a longitudinal, downwardly facing semi-cylindrical channel of substantial depth, into which water that in the operation of the common type of boat would be shoved forwardly, downwardly or laterally by the bottom and bow in the forward travel of the boat, will of the propeller or propellers and moved through the channel to the stern of the boat, and there forcibly discharged rearwardly with jet-like propelling effect, to fill in the cavity that otherwise would be formed incident to the forward travel of the boat. Thus, by this design, I eliminate both the usual retarding pressure of displacement water against the bow of the forwardly moving boat and the speed reducing drag of cavitation and after-tow.
It is a further object of the present invention to so shape the sides and bottom of the longitudinal channel as provided in the bottom of the hull, and to so dispose a keel and the driving propeller or propellers in the channel that the latter will move water from the forward end of the boat therein sternward in two parallel streams and will discharge it with jet-like propelling effect, and in the sucking of water into the channel at its forward end will tend to create a cavity in the keel divided channel, forwardly of the propellers, into which the waters which are normally divided and outwardly displaced by the bow will converge and thus the usual retarding effect of Water headed into by the boats prow will be eliminated.
Still another object of my invention is to provide a hull construction for boats that is characterized by those features of construction above recited and wherein the channel as formed in the bottom of the hull is centrally and longitudinally divided by a keel that extends from the bow end to a substantial distance rearward thereof, and in which keel, a propeller shaft and drive gear housing is incorporated as a part of or an extension of the keel; this housing being of such nature as to somewhat constrict with vcnturi effect the two ducts into which the channel is divided by the keel so that the action of propellers, located in keel openings forwardly and rearwardly of this gear housing, will result in accelerated flow of water in the ducts at the places of restriction and a forced ducts that is of greater speed than be drawn by the action ttes atent 2,735,392 Patented Feb. 21, 1956 the relative rearward travel of water along the sides of the hull, so that after-tow and the folding in of the water around the stern will be avoided.
Yet another object of the invention is to so design the opposite sides of the present hull that the water along the outside thereof is practically undisturbed by the forward travel of the hull and is restrained from rushing from along the sides of the boat into the longitudinal channel or duets with retarding effect on the rearwardly propelled streams of water in the channel.
It is a further object of my invention to provide a boat hull of specific and novel design, featuring the provision in its bottom of a longitudinal channel that is centrally and longitudinally divided for at least a part of its length by a keel, a portion of which keel incorporates means therein for transmitting power to the propeller or propellers and also provides a low center of gravity that gives greater stability and adds sea worthiness to the boat.
In accomplishing these and other objects of the invention, l have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherein- Fig. 1 is a side view of the hull of a boat embodying the improvements of the present invention therein; parts thereof being broken away for better understanding.
Fig. 2 is a bottom view of the hull, showing the central channel and extent of the keel dividing the channel in two parallel passages; also showing the propeller locations.
Fig. 3 is an elevation of the hull, as seen from directly forward of the prow.
Fig. 4 is an elevation of the hull, as seen from directly rearward of the stern.
Fig. 5 is a partial plan view substantlialy at deck level, of structural members in the hull construction, and showing the location of rudders.
Figs. 6, 7 and 8 are cross-sectional views taken on lines 66, 7-7 and 88, respectively, in Fig. 2.
Referring more in detail to the drawings- First describing the novel features of design and the particular shaping of the water contacting surfaces of the present hull:
The hull, which is designated in its entirety by reference numeral 10, is shown more particularly in Figs. 1 and 2, to be conventional in its general outline and plan, and in so far as its structure from the water line downwardiy is concerned, it has vertical and parallel opposite side walls 11-11 extending substantially to its full length. The chine lines 12, where the side walls Ill-11 join with the bottom, 13, are straight from end to end and are uniform in depth below the water line. water line is designated in the various cross-sectional views by line W-W.
downwardly and rearwardly rounded edges designated at S in Figs. 1 and 2. Likewise, it is to be observed that the main portion of the stern structure of the hull is above the water line and extends rearwardly of the sides 11 of the hull which are shown to terminate in the rudder mounts 'S'.
in the various cross-sectional views, the hull bottom 13 is shown to be upwardly transversely arched in substantially a semi-cylindrically curved form, thus forming the hull, from stem to stern, with a longitudinal, downwardly facing channel. This channel extends substantially to the full width of the hull as defined by the opposite side walls 11-11, and the top of the arch extends along the central longitudinal plane of the hull at a level just slightly below the horizontal plane of the water line.
It will be understood by reference to the several crosssectional views that, in effect, the hull comprises two laterally spaced and longitudinally extending hull sections 11a and 11b which are so designed as to elfect sufficient displacement of water that the hull will be caused to float at the desired level. The upwardly arched inside walls of these two hull sections together define the inverted central longitudinal channel of the hull and the vertical side walls thereof operate to hold back outside Waters, that are other than displaced waters, from the channel and propellers. Thus, the positioning of propellers in the channel as presently explained is of great importance especiallyin respect to the forward propeller, which has the duty of producing cavitation to accommo date the oncoming bows water and reduce resistance to forward travel resisting. The greater the cavitation or suction produced, the less will be the bow resisting pressure.
The present invention further provides that the longitudinal channel formed by the transversely arched bottom is longitudinally divided at least for a portion of its length, by a keel 18. The keel is shown in Figs. 1 and 2, to extend rearwardly from the point of the bow to about two thirds the length of the hull. However, in some instances it might be extended to the stern end if found necessary or desirable to meet various requirements.
The keel extends to a depth slightly below the level of the chine lines of the opposite side sections 11:: and 11b and at its forward end its edge is gradually curved upwardly to the prow, as at k in Fig. 1. It is anticipated that in some boats, using a single propeller, located amidships, the keel would terminate at the location of the propeller. Furthermore, in some boats, especially those of small size, such as those boats using out-board motors or similar means for propulsion, a central keel would not be required and could be omitted.
It is herein illustrated that the keel 18 divides the longitudinal channel into two co-extensive, parallel passages or ducts which in the elevational and cross-sectional views are designated at p and p. These ducts extend from the bow to the rear end of the keel where they merge. At its forward end, the channel as formed by the arched bottom, has outwardly flared entrance valleys or mouths into which water from immediately forwardly of the bow ends of hull and side sections, referred to herein as head water is sucked by the propeller action as distinguished from the usual forward, lateral and downward forcing of this water by the forwardly traveling boat.
To provide these flared entrances to the channel, the curved top wall is gradually upwardly and outwardly formed to define a sort of valley leading into each side of the channel. The valleys are designated at V and V in Figs. 2 and 3, and they serve, in the forward travel of the bull in the water, to accelerate movement of displacement or head waters into the channel and toward the propellers.
The action of the propellers in forward of the bow ends of the boat into the dual passages or ducts and discharging it rearwardly tends to create a cavity immediately forward of the bows and to move the displaced water rearwardly through the channel to the rear of the forward propeller and discharge it to the stern end thus to eliminate cavitation at the stern and prevent any retarding after-tow. If a single propeller should be used, it would be so located and operated as to perform the functions of the two propellers, as herein illustrated.
in Fig. 2 of the present used to indicate direction of ter from the ducts under influence is indicated that the water is drawn into the forward ends of the dual passages p and p from forwardly and laterally of the bows point and that it is discharged from the sucking the water from drawings, arrows have been inflow and discharge of waof the propellers. It
rear end of the bottom channel and diverges laterally. The straight, upright outer side walls of the hull have no tendency as the boat moves forwardly to cause any outward or lateral movement of water at the outside thereof and they serve to prevent the water at the sides of the hull entering the passages. For this reason the propellers are not affected by and do not have to move a any Water except that contained in the passages and received from the forward end of the hull.
The location of propellers is dependent somewhat on boat requirements. In the present instance, I have illustrated the hull asequipped with two propellers 25 and 26 which respectively, are located in the plane of keel 18 about one-third and two-thirds of the distance from stem to stern. The forward propeller 25 is disposed within a recess 25R in the keel and extends equally into each duct 2 and p, while the rearward propeller 26 is located immediately beyond the terminating edge of the keel or housing 18x which is a component thereof and which will now be described.
Formed as a component part of or in combination with the keel, as a rearward extension of the forwardly located keel 18, is a housing which is designated by reference character 18x and which is that portion of the keel located between the propellers 25 and 26. The spaced, opposite side walls of this housing converge forwardly to merge gradually into the relatively narrow keel as shown best in Fig. '2. Likewise they converge rearwardly to a feather edge just forwardly of the propeller 26. Also, these walls converge downwardly to a thin edge that coincides with the bottom longitudinal edge of the keel.
Contained in the housing 18x, which will hereinafter be referred to as a pontoon or swell, lengthwise thereof are the propellermounting and driving shafts 25s and 26s which, respectively, mount the propellers 25 and 26 thereon. These shafts are equipped with sprocket wheels over which driving chain belts 2'7 and 28 operate to drive the shafts; these belts being driven by engines designated in Fig. l at 29 and 30.
' The embodiment of the swell 13x in or with the keel 18 causes the two passages p and p, as separated thereby to be somewhat constricted at the location of the section line 7-7, and thus the propellers coact more effectively to discharge the incoming water rearwardly with jet-like propelling action. The rearward end of the channel is fantailed into the hull to give a flared effect that results in the easy rearward and lateral discharge of the streams of water from the passages.
The propeller shafts, their supporting bearings, and propellers add weight at a particular location that results in a low center of gravity that gives stability and better balance to the boat.
With the hull constructed in this manner, it can be understood that the sides of the hull cut through the water, retaining that at the outside of the hull from the longitudinal channel. Only that water that enters the channel at its forward end must be moved by the propellers and the channel passages are so shaped that, under the influence of the propellers, especially the forward one, there is a tendency to produce a cavity forward of the bow into which the boat advances without head water resistance. The propellers, being located in the ducts at points where the pressure of rearwardly flowing water accumulates, will operate with greatest efficiency in effecting the jet-like propulsion of the water from the rear end of the channel to drive the boat forward and to overcome cavitation and after-tow.
Since the water pressures as sustained by the present hull are substantially reversed from those as applied to normal construction, a different frame structure than ordinarily used is desirable. Strong bulkheads are neees sary, especially on how ends, to give the necessary a strength.
A pattern of the preferred constfuction is shown in Figs.
5 to 8; Fig. 5 being a horizontal section taken just below deck level, that is, at about the water line.
In Fig. 5, longitudinal plates 40 and 41, disposed horizontally and in vertical spacing, are shown to be extended between the side walls 11 and the upwardly arched bottom 13, and these provide water tight cornpartments between them that extend to substantially the full length of the hull.
Across the top of the arch as formed by the bottom plate 13, are transversely directed plates 45, best seen in Fig. 5; these being disposed vertically on edge and welded to the bottom and also to those portions of the plates 41 with which their opposite end portions overlap. The end edges of the cross-plates 45 are welded to longitudinals 4848 which are disposed vertically on edge and equally inwardly spaced from the opposite side walls 11. Division plates 49 are extended between the longitudinals and adjacent sidewalls 11. Also, other division plates 50 located between the plates 40 and 41 are extended between the arched bottom 13 and the side walls. The division plates 49 are staggered relative to the spacing of plates 50 as will be understood by reference to the showing of these parts in Fig. 5.
The main deck of the boat is designated at 55 in Figs. 6, 7 and 8 and it is supported by the longitudinals 48 and cross plates 45 and is welded to the side walls 11-11 It is shown in the several views that, above the deck 55, the side walls of the hull are outwardly curved, and between these walls and upper structure, suitable bracing is provided.
The particular arrangement of longitudinals and cross beams and division plates as shown in Figs. 5 and 8, properly welded together gives all strength required and solves the various problems of shrinkage, strains and contortions with which builders of such craft are quite familiar.
The various compartments provided can be used for storage space, for fuel, water, cargo, etc.
In Fig. 5, I have shown rudders 60-60 arranged at sides beyond but in alignment with the side walls. However, the location of rudders and number used would depend somewhat upon type or size of boat. It might in some cases be more practical to employ a single rudder, located in alignment with the keel.
The feature whereby the present invention is characterized, broadly stated, is the collecting of the displacement waters by the bows and forcing them centerwise beneath the bottom, and locating a propeller at the point where the peak of pressure of the displacement waters accumulates according to speed; the propeller operating to force the displacement sternward, leaving a cavity for oncoming bows waters and pressures to fall into. The displacement, then under propeller pressure, pressing against waters at the stem with elimination of the after-drag.
Having thus described my invention, what I claim as new therein, and desire to secure by Letters Patent, is:
l. A boat having a hull formed with a water dividing prow and with opposite sidewall portions extending substantially to the full length of the hull in parallel vertical planes and to equal, uniform depth, and said hull having a bottom of upwardly arched and substantially semi-cylindrical form, extended between and joined with said sidewall portions along their lower edges and providing a water confining channel that opens to prow and stern ends of the boat, said bottom having outwardly and upwardly formed portions at its forward end, at opposite sides of the prow, joined with the forward ends of said sidewall portions to provide cut-waters and forming upwardly and laterally flared valleys whereby head waters are funneled into said channel, as the boat moves forwardly and said bottom having similarly upwardly formed portions at its rear end, joined with the rear ends of said sidewall portions; said bottom and said sidewall portions as thus joined providing parallel, laterally spaced water displacement bows whereby the hull is floated in the water with the top of the arched bottom substantially at the level of the water line, and a boat driving propeller positioned in said channel in its central longitudinal plane and substantially above the level of the lower edges of said sidewall portions of the hull.
2. A boat as in claim 1 wherein a keel is formed centrally along the boat bottom, extending to the full depth of the sidewalls and dividing said channel into dual passages, and propellers set in the keel and operable to effect the forced flow of channel waters in said dual passages for propulsion of the boat.
3. A boat as in claim 2 wherein a keel is formed centrally along the boat bottom, extending substantially to the depth of said sidewall portions, and dividing said channel into dual passages; said keel being provided along one part thereof with a swell of passage constricting formation, providing venturis through which the channel confined waters are caused to flow, under the propeller influence with increased velocity and discharged therethrough with jet action.
References Cited in the file of this patent UNITED STATES PATENTS 923,123 Ishoy May 25, 1909 1,061,826 Didlake May 13, 1913 1,599,312 Passy-De Chimang Sept. 7, 1926 1,886,471 Passy-De Chimang Nov. 8, 1932 2,356,349 Persson Aug. 22, 1944 2,366,590 Brownback Jan. 2, 1945 FOREIGN PATENTS 2,813 Great Britain July 24, 1877 341,059 France May 31, 1904 408,278 Germany Jan. 12, 1925