US2220875A

US2220875A - Boat construction

Info

Publication number: US2220875A
Application number: US231196A
Authority: US
Inventors: Lloyd G Barker; Edmund N Todd
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-09-22
Filing date: 1938-09-22
Publication date: 1940-11-12
Anticipated expiration: 1957-11-12

Description

Nov. 12, 1940. L GBARKER A 2,220,875

BOAT CONSTRUCTION Filed Sept. 22, 1938 3 Sheets-Sheet l INVENTORS 1L0 yo 6. BARKER [bMl/ND IV 7500 W 7 IT ORNEY.

AND

Nov; 12, 1940. L, RK 2,220,875

BOAT CONSTRUCTION Filed Sept. 22) 1938 5 Sheets-Sheet 5 FIG 9 Z IIg EBNTORS L0 r0 AR/(ER 39/ 3+ BY M fOMUND N. T000 ATTORNEY.

iii]

PatentedNov. 12, 1940 BOAT CONSTRUCTION Lloyd G. Barker and Edmund N. Todd,

Miami, Fla.

Application September 22,1938, Serial No. 231,196

4 Claims.

Our invention relates to boats and to the method of making the same.

Our invention is directed to boats of 'the type which have rounded sides which extend from a pointed bow around the beam of the boat to a blunt stern. Boats of this general type have heretofore been made of strips or slats of material fitted together, each strip of material being bent longitudinally of the strip to conform to the shape of the boat. Use of canvas, rubber or metal has been adopted in some instances as such material could be curved or bent both longitudinally and transversely of the sheet of material. However, it has heretofore been considered that semi-rigid material such as plywoodcould not be utilized in forming the shell of such a boat due to the nature of the plywood in resisting curvature and the inherent character of the curves of a boat of this general type.

The plywood which we use is made up of a plurality of sheets of wood veneer joined together by marine glue or other suitable binder. This laminated material offers great strength when utilized in our construction, is waterproof, and is an excellent material for the construction of boats. Our invention offers the advantages of such plywood in the construction of this class of boat. The plywood is not fully resilient and due to its semi-rigid nature can be only partially flexed in wide sweeping curves of simple form. Our invention overcomes the obstacles to the use of such plywood and gains the advantages oifered by the character of such material. By following the teaching of our invention, boats of great merit and superior nature to other boats heretofore known are produced. Other sheet material of similar nature and of equivalent character may be utilized and is intended as included within the scope of the invention.

Our invention also provides a boat of unique design having greater stability in the'water and possessing a greater degree of seaworthiness. The shape and construction of our boat is such that a new and unexpected result has been obtained in the actual use of the boat. Our invention, therefore, includes a novel and improved method of construction of boats and the boat as a new article of manufacture.

One of the objects of our invention is to provide an improved method of constructing a boat.

Another object is to provide a method of forming the shell or hull of a boat.

Another object is to provide a method of forming plywood into the shape of the shell of a boat without steaming or pre-forming the plywood.

Another object is to provide a method of forming the shell of a boat, which method is adapted to the natural characteristics of the plywood in conforming the plywood. to the desired shape.

Another object is to provide a method of formr osslcsf ing a sheet of plywood into the shell of a boat without distortion or undue strain to the plywood. Another object is to provide a boat having a maximum of strength and permanence and with a minimum of seams in the shell of the boat.

Another object is to provide a boat having an improved design giving superior result in use.

Another object is to provide a boat having increased stability and buoyancy.

Another object is to provide a boat having better seaworthiness then other boats of the same general type.

Another object is to provide a boat economical of construction and maintenance. l

A still further object is to provide a boat formed for greater efiiciency in use.

Other objects and a fuller understanding of our invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

Figure 1 is a plan view. looking down into the open top of our boat;

Figure 2 is a side elevational view of the shell of our boat;

turned up-side-down;

Figure 4 is an elevational view of a part of the frame of our boat;

Figure 5 illustrates a working table upon which the shell of the boat is formed;

Figure 6 is a cross-sectional view taken through the boat placed up-side-down upon the working table shown in Figure 5; p

Figure 7 is a plan view of a single sheet or plywood utilized in forming the shell of the boat;

Figure 8 illustrates the utilization of two sheets of plywood in forming the shell of the boat; and

Figure 9 illustrates the utilization of four pieces of plywood utilized in forming the shell of the boat.

The shape and construction of our boat is determined by the form of the plywood shell rather than by a predetermined design of the frame. Since the shape of the boat must conform to the natural aptitude of the plywood to bend without steaming or other processing, the final design is determined by the shape to which a cut piece of plywood may be 'bent. A pieceof plywood made up of laminated veneer glued together is layed in the flat as shown in Figure '7. The sheet of plywood 32 is cut around its edges to conform to the outer outline of the shell to be formed. A longitudinal V-shaped slit is cut into the plywood 32 at th e end where the bow is to be located. This longitudinal slit cut substantially as shown in Figure 7 has opposite edges 33 which extend inwardly and meet. There are also two transverse slits cut into the plywood 32 from oppositeedges at the point where the beam of the shell is to be located. In speaking of the beam of the boat or shell, the term is to be understood to referring to the location of the boat at its greatest width. This beam is located intermediate of the bow and of the stern of the boat and in the illustration shown is slightly in advance of the center of the boat. The two transverse slits are relatively narrow and V-shaped and become much narrower as the slits extend inwardly of the plywood 32.

The transverse slits have opposite edges 34 which,

when drawn together, are adapted to form a seam at the beam of the shell. These opposite edges 34 converge inwardly of the sheet of material 32.

The sheet of material 32 shown in Figure '7 may be formed into the shell of the boat by bending the plywood to draw the opposite longitudinal edges towards each other. By abutting the opposite edges 33, the bow end is closed and by abutting the opposite edges 34, the curved sides of the shell at the beam is closed. The sheet of material 32 thus forms a shell of a boat lacking only the stern piece to close the stern end and lacking the frame work for bracing and strengthening the shell.

Details of the frame construction are illustrated in Figures 1 and 4. In the plan view of the completed boat shown in Figure 1, there is shown the several members of the frame. The

keelson extends the length of the boat along I the bottom thereof. The bottom ribs I3, I5, I'I, I9, 2|, and 23, are jointed to, and bolted or otherwise secured to the keelson II. Each of the bottom ribs has side ribs extending up from the ends thereof, the outer surfaces of the bottom ribs and the respective side ribs being disposed in a gradual curve as is illustrated in Figure 6. The side ribs are secured to the ends of the bottom ribs by bolts extending through the ribs. The side ribs I4 are secured to the bottom rib I3, the side ribs I6 are secured tothe bottom rib I5, the side ribs I8 are secured to the bottom rib H, the side ribs 20 are secured to the bottom rib I9, the side ribs 22 are secured to the bottom rib 2 I, the side ribs 24 are-secured to the bottom rib 23. The transverse shape of the assembled ribs are substantially that illustrated for ribs I5 and I6 shown in Figure'G, The longitudinal members or chines 25 and 26 extend longitudinally of the boat upon each side of the keelson I. The bow ends of the

chines

25 and 26 and the keelson I| converge to, and are secured by bolts to, the stem piece 3E1, and there form the framework of the bow. The stern end of the

chines

25 and 26 and keelson I I terminate'at, and are secured to, the stern piece I2. The stem piece I2 is thereby made a part of the frame and supplements the shell formed by the plywood 32 forming the hull of the boat. The stem piece I2 is sloped at an angle outwardly from the bottom of the boat as illustrated in Figures 1 and 4. The upper ends of the side ribs are joined together and braced by the hand rails 28 which are secured to the upper ends of the side ribs by bolts or other means, and are mounted upon the inner side of the side ribs. The shell formed by the bent piece of plywood 32 fits around the outside of the frame and is secured to the members thereof by rivets, nails, or other suitable means. The shape and dimension of the several members of the frame are such that the frame fits snugly against the sides of the shell and acts as a firm support and brace for the shell. The upper edges of the shell of plywood 32 are bound by the gunwhales 29'which extend around the periphery of the shell at the edge of the boat and help secure the shell and the frame together. In order to provide a backing and splice for the seam formed by the edges 34, straps 3| comprising pieces of plywood are mounted upon the outside surface of the ribs I9 and ZEI at the location of the beam, 2 In order to keep from cutting into the chines, several separate straps 3| are utilized which extend around the outer surface of the ribs I9 and 20 intermediate the several chines and keelson.

Straps 3| are wider than the ribs and provide a good substantial backing for the seams formed by the edges 34. By placing the straps 3| in the position illustrated, a relatively Wide expanse of wood is provided back of the seams providing an improved support for the edges of the seams and better closing the seams, As the plywood from which the straps 3| are formed are possibly onequarter inch in thickness, the ribs I9 and 20 are reduced in size that amount to compensate for this thickness and provide a smooth uninterrupted surface next to the interior of the shell at the point of the transverse seams at the location of the beam.

By reason of the semi-rigid nature of the sheet of plywood 32 and its resistance to bending sharply or in more than one direction, a completely smooth and progressive curve at the beam is not afforded. At the location of the joinder of the edges 34, there is a bulge or outward projection which may increase in size toward the upper edge of the boat and disappears into the smooth outer curve of the shell toward the bottom of the boat. This bulge 4| is substantially confined above the water line of the shell and does not offer any disadvantage to forward movement of the boat. It has been found that the bulge provided at the beam by the joinder of the edges of the plywood greatly stabilizes the boat in rough water and in the turning of the boat. The bulge 4| while relatively small provides a stabilizing effect greatly in excess of that which could be expected from its size. The overhanging bulge or projection acts as an outrigger and greatly increases the seaworthiness of the boat. The sides of the boat at the gunwhale bend around the beam in a gradual slope back from the bow and extend back to the stern. The smooth and gradual curve of the sides longitudinally of the boat are substantially continuous and progressive, except for the bulges 4| formed at the beam, the bulges 4| exaggerating the curve of the sides at those points.

The above description may be made clearer by referring to Figure 3 of the drawings which illustrate the features of our invention of making the bow and stern shell portions possess sur face cruvatures in more than one dimensional direction. The surface curvatures are made up of a plurality of localized shell areas possessing different simple surface curvatures from each other. The localized shell area represented by reference character 5|] near the bottom of and on each side of the bow portion extending longitudinally of the boat in a diverging direction from the bow to the beam, is bent in a simple transverse curvature in an upward direction from the bottom of the boat to the gunwhales. The maximum curvature is concentrated near the bottom of the boat and is disposed in a straight line from the bow to the beam as indicated by the concentrated shading lines in reference character 50. The 10- calized shell areas indicated by the reference character 5| near the bottom of and on each side of the stern portion extending longitudinally of the boat from the beam to the stern is bent in a simpletransverse curvature in an upward dlrection from the bottom of the shell to the gunwhales. The maximum curvature is concentrated near the bottom of the boat and is disposed in a straight line from the beam to the stern as indi-'- cated by the concentrated shading lines in reference character The joining ends of the longitudinal shell areas indicated by the reference characters 50 and 5! of the bow and stern portions having the simple transverse curvatures register with each other at the beam to make substantially an angular junction at 52 defining the sharpest portion of the bulge M for stabilizing the boat.

The localized shell areas 53 near the upper edge of, and on each side of, the bow portion extending longitudinally of the boat from the bow to the beam is bent in a simple longitudinal curvature in an outward direction to make the upper edge of each side of the bow portion to have a gradual longitudinal curvature or sweep as best illustrated in Figures 1 and 3.

The localized shell area 5 near the upper edge of, and on each side of, the stern portion extending longitudinally of the boat from the stern to the beam is bent in a simple longitudinal curvature in a slightly outward direction to make the upper edge of each side of the stern portion to have a gradual longitudinal sweep as shown in Figures 1 and 3.

The localized shell areas of the simple transverse curvatures 5 and 5! and the localized shell areas of the simple longitudinal curvatures 53 and 5 are separated from each other to cause the strain of the said longitudinal shell areas to be substantially free from each other. That is to say, the localized shell areas having different.

simple curvatures from each other are at a distance from each other to relieve the respective localized shell areas from the strain of the other. Our construction permits the bow and stern portions in the main to possess surface curvatures in more than one dimensional direction, even though the sheet material for the boat shell rcsists stretching, compressing and curving in more than one direction in the same local areas.

The portion of the shell on the bottom of the boat between the bow and stern lies substantially in the same plane and thus when the boat runs through the water the substantially angular junctions 52 at the registration of maximum curvatures 5! and 52 are above the water. In other words, the substantially angular meeting of the shell areas at the maximum curvatures 5! and 52 does not manifest itself upon the bottom of the boat which normally lies under the water; Therefore, when the boat is running normally in a straight path through smooth water and in a vertical manner the substantially angular junctions defined by the registration of maximum curvatures 5! and 52 do not come into play, but when the boat is running at a tilt as it will be when going around a curve, the substantially angular joining of the registration of maximum curvatures 5! and 52 then come into play and act as a pivot or additional keel to keep the boat from skidding as it would attempt to do in the, absence of the stabilizing effect alforded by our construction.

Therefore, we have solved the problem of making a round-bottom boat of stiff sheet'material in terms of localized curvatures separated from each other. The solution isbrought about by the combination of the two shell portions of the bow and stern having certain characteristics, which when combined form a boat with continuous straight or curved lines from bow to stern, ex.-

c'ept for the localized areas at the junctures 52 of the maximum transverse curvatures 50 and 5! where the continuous lines form an angle rather than a smooth curve.

The construction of the boat may be carried on by utilizing a work. table such as that shown in Figure 5. two long bars 43 resting upon supports 48. The brace members Ml carried by the long bars 43 incline toward each other and support the top bar 45 forming a gable construction. The top bar d5 has cut out portions or hitches 46 spaced therein at intervals. There are a plurality of cross-pieces 4'! extending across between the bars 53 and spaced at intervals from each other, as illustrated. A framework similar to that illustrated in Figure 4 is inverted over the top of the work table shown in Figure 5. The frame has been designed and constructed so as to conform with the shape which the plywood will take upon being bent. Since the exact geometrical contour of the bent plywood is difiicult to calculate, it is sometimes easier and quicker to omit some of the side ribs in initial construction and assembly of the frame. Therefore, in the frame shown in Figure 4:, the side ribs l4, l8, and 22 have been omitted and are not shown in the assembled frame. The omitted side ribs are assembled to the rest of the frame after the shell is in place so that a snug engagement may be made by moving the omitted ribs up close to the walls of the shell before fastening them into place.

In the inverted position, the keelson l I rests upon the top of the topmember 45 of the construction table and the bottom ribs are accommodated by the cut out portions or nitches 46 in the top member 35. The ends of the side ribs and the hand rail rests upon the top of the crosspieces d! and in this manner, a secure and rigid support is given to the assembled frame. The sheet of plywood 32 similar to that shown in Figure 7 is placed over the top of the partial frame and correctly aligned with the longitudinal slit forming the edges 33 positioned at the bow end. Several ropes or straps are placed across the top of the plywood 32 resting upon the frame, the ropes being positioned substantially transversely of the plywood. The ends. of the several ropes or straps are suitably engaged to pulley means anchored to the floor upon which the support 48 rests. By manipulation of the ropes through the pulleys, the ropes arepulled down tightly upon the top of the plywood 32 causing the plywood to flex and to bend into theshape of the shell. By tying the ropes down, the plywood is shaped such that the edges of the plywood are drawn toward each other to conform to the shape of the shell. The opposite edges 33 are drawn toward'each other and in abutment to form the bow end of the shell. edges 35 are drawn toward each other to form the seams at the location of the beam. The portions immediately adjacent to the edges 34 being somewhat rigid do not conform exactly to the general curvature of the sides of the boat and thereby form the bulges 4!. The conformed shell of plywood and the frame are then secured to each other by nails, rivets, or other suitable means. The nails may be driven through the plywood into the ribs and chines. The gunwhales or side strips 29 may then be secured to the shell and the framework, the gunwhales being mounted on the outside of the shell adjacent the edge thereof and bolts extending through the gun- The work table illustrated has the The opposite whales, the plywood, the ribs, and the handrail 28, forming a secure attachment between the several parts. 'At the bow end, the plywood adjacent to the edges 33 is secured by nails or other suitable means to the stem piece 30 and the forward end of the keelson I. The plywood is placed upon the outside of the stem piece 30 so that the edges 33 abut and form the most forward part of the bow. The portions of the plywood adjacent the edges 34 are secured by nails or rivets, or other suitable means to the straps 3| and the ribs 20. The stem end of the plywood 32 formed into the shell is secured by nails, rivets, or other suitable means to the stern piece l2, the plywood overlapping the edges of the stern piece I2 as is illustrated in Figure 1.

Figure 6, being a cross-sectional view of the boat upon the construction table, illustrates the step of bending the plywood into the shape of the shell, the frame being in position under the plywood ready to be attached thereto. For purpose of illustration the right-hand side of the plywood is shown down in position completely curved while the left-hand side of the plywood is shown as only partially bent. In practice, both sides are bent down together and simultaneously, by reason of the pulling action of the ropes extending across the top of the plywood.

An alternative method of shaping the plywood into' the form of the shell is provided by using a form having a recess conforming to the shape of the shell. The plywood may thus be forced up against the side of the recess to force it into the proper contour of the shell.

The frame and shell assembled together are removed from the Work table and the side ribs which have been omitted are then placed in position and bolted to their respective bottom ribs. The omitted side ribs are pressed into close engagement with the shell before being bolted and by thus securing the close conformity between the shell and the frame, a strong durable boat is constructed. It is to be understood, however, that by proper predetermined design the frame may be entirely constructed and assembled before the shell is formed and fastened to the frame. The omission of parts of the frame prior to assembly with the shell permits the taking up of any leeway or play between the parts and insures a good tight engagement between the shell and the frame.

After construction in the described manner, the boat is caulked along the seams to prevent possible leakage and is then painted in the usual manner.

The resulting boat is economical in construction and requires a minimum of repairs by reason of its sturdy structure and the presence of only a minimum of seams. The boat constructed in accordance with our invention has a greatly increased stability in use. The greater efficiency of the boat in its intended uses has provided a real and recognized improvement in boats of this general type.

In the construction of larger boats, or when large sheets of plywood are not commercially available, it is sometimes not feasible or practical to use only a single sheet of plywood as illustrated in Figure '7 for forming the entire shell of the boat. In such a situation, it may be necessary to use two or four pieces of flat plywood to form the entire shell of the boat. In Figure 8, there is illustrated, the use of sheets of plywood 35 and 36. Piece 35 forms at the stem end of the boat and piece 36 forms at the bow end of the boat, the pieces abutting closely together to form a seam extending around the boat at the beam. In effect, the pieces 35 and 36 are the same as the single piece 32 and in the construction of the shell, it is the same.

In Figure 9 is illustrated the use of four pieces of plywood.

Pieces

31, 38, 39, and 40 as shown in Figure 9 form substantially a quarter each of the shell of the boat. Pieces 3! and 39 are positioned at the stern end and pieces 38 and 40 are positioned at the bow end. By the use of four pieces, there is a longitudinal seam extending down parallel to the keelson formed by the abutting edges of the pieces of plywood on each side of the boat. There is also the seam formed by the abutting edges of the plywood extending around the shell at the beam. In both cases, the half sections of Figure 8 and the quarter sections of Figure 9, the forming of the shell and its assembly to the frame is the same as that described in the case of the single piece of plywood 32.

Although we have described our invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to Without departing from the spirit and the scope of the invention as hereinafter claimed.

We claim as our invention:

1. A boat shell having a bow portion and a stern portion meeting at the beam of the boat, said boat being wider at the beam than at the bow, the shell of the bow portion on each side of the bow comprising an integral sheet of material which resists stretching, compressing and curving in more than one direction in the same localized area, said bow portion in the main possessing surface curvatures in more than one dimensional direction made up of a plurality of localized shell areas possessing different simple surface curvatures from each other, the localized shell areas of the sheet of material near the bottom of, and on each side of, the bow portion extending longitudinally of the boat in diverging directions from the bow to the beam being bent in a simple transverse curvature in an upward direction, the upper localized shell areas near the upper edge of the sheet of material on each side of the bow portion extending longitudinally of the boat from the bow to the beam being bent in a simple longitudinal curvature in an outward direction to make the upper edge of each side of the bow portion to have a. gradual longitudinal curvature, the said localized shell areas of the transverse simple curvature and the said localized shell areas of the longitudinal simple curvature being spaced, at a distance from each other to cause the strain of the localized shell areas to be substantially free from each other.

'2. A boat shell having a bow portion and a stern portion meeting at the beam of the boat, said boat being wider at the beam than at the bow and at the stern, the shell of the bow portion comprising sheet material which resists stretching, compressing and curving in more than one direction in the same localized area, said bow portion in the main possessing surface curvatures in more than one dimensional direction made up of a plurality of localized shell areas possessing difierent simple surface curvatures from each other, the localized shell areas of the sheet material near the bottom of, and on each side of, the bow portion extending longitudinally of the boat in diverging directions from the bow to the beam being bent in a simple transverse curvature in an upward direction, the upper localized shell areas near the upper edge of each side of the bow portion extending longitudinally of the boat from the bow to the beam being bent in a simple longitudinal curvature in an outward direction to make the upper edge of each side of the bow portion to have a gradual longitudinal curvature, the said localized shell areas of the transverse simple curvature and the said localized shell areas of the longitudinal simple curvature being spaced at a distance from each other to cause the strain of the localized shell areas to be substantially free from each other, the shell of the stern portion comprising sheet material which resists concentrated bending in more than one dimensional direction, said stern portion in the main possessing surface curvatures in more than one dimensional direction made up of a plurality of localized shell areas possessing difierent simple surface curvatures from each other, the localized shell areas of the sheet material near the bottom of and on each side of the stern portion extending longitudinally of the boat from the beam to the stern being bent in a simple transverse curvature in an upward direction, the upper localized shell areas near the upper edge of each side of the stern portion extending longitudinally of the boat from the beam to the stern being bent in a simple longitudinal curvature in an outward direction to make the upper edge of each side of the stern portion to have a gradual longitudinal curvature,

the said localized shell areas of the stern portion of the transverse simple curvature and the said localized shell areas of the longitudinal simple curvature being spaced at a distance from each other to cause the strain of the localized shell areas to be substantially free from each other.

3. A boat shell having a bow portion and a stern portion meeting at the beam of the boat, said boat being wider at the beam than at the bow, the shell of the bow portion comprising sheet material which resists stretching, compressing and curving in more than one direction in the same localized area, said bow portion in the main possessing surface curvatures in more than one dimensional direction made up of a plurality of localized shell areas possessing different simple surface curvatures from each other, the localized shell areas of the sheet material near the bottom of and on each side of the bow portion extending longitudinally of the boat in diverging directions from the bow to the beam being bent in a simple transverse curvature in an upward direction, the upper localized shell areas near the upper edge of each side of the bow portion extending longitudinally of the boat from the bow to the beam being bent in a simple longitudinal curvature in an outward direction to make the upper edge of each side of the bow portion to have a gradual longitudinal curvature, the said localized shell areas of the transverse simple curvature and the said localized shell areas of the longitudinal simple curvature being spaced at a distance from each other to cause the strain of the localized shell areas to be substantially free from each other, the shell of the stern portion comprising sheet material which resists concentrated bending in more than one dimensional direction, said stern portion in the main possessing surface curvature in more than one dimensional direction made up of a plurality of localized shell areas possessing different simple surface curvatures from each other, the localized shell areas of the sheet material near the bottom of and on each side of the stern portion extending longitudinally of the boat from the beam to the stern being bent in a simple transverse curvature in an upward direction, the upper localized shell areas near the upper edge of each side of the stern portion extending longitudinally of the boat from the beam to the stern being bent in a simple longitudinal curvature in an outward direction to make the upper edge of each side of the stern portion to have a gradual longitudinal curvature, the said localized shell areas of the stern portion of the transverse simple curvature and the said localized shell areas of the longitudinal simple curvature being spaced at .a distance from each other to cause the strain of the localized shell areas to be substantially free from each other, the joining ends of the localized shell areas of the bow and stern portions having the simple transverse curvature registering with each other to make substantially an angular junction defining a bulge for stabilizing the boat, the joining ends of the localized shell areas of the bow and stern portion having the simplelongitudinal curvatures registering with each other to make a continuous and gradually curved upper edge from the bow to stern.

4. A boat shell having a bow portion and a stern portion meeting at the beam of the boat, said boat being wider at the beam than at the how, the shell of the bow portion comprising sheet material which resists stretching compressing and curving in more than one direction in the same localized area, said bow portion in the main possessing surface curvatures in more than one dimensional direction made up of a plurality of localized shell areas possessing different simple surface curvatures from each other, the localized shell areas of the sheet material near the bottom of, and on each side of, the bow portion extending longitudinally of the boat in diverging directions from the bow to the beam being bent in a simple transverse curvature in an upward direction, the upper localized shell areas near the upper edge of each side of the bow portion extending longitudinally of the boat from the bow to the beam being bent in a simple longitudinal curvature in an outward direction to make the upper edge of each side of the bow portion to have a gradual longitudinal curvature, the said localized shell areas of the transverse simple curvature and the said localized shell areeas of the longitudinal simple curvature being spaced at a distance from each other to cause the strain of the localized shell areas to be substantially free from each other, the shell of the stern portion comprising sheet material, the localized shell areas of the sheet material near the bottom of and on each side of the stern portion extending longitudinally of the boat from the beam to the stern being bent in a simple transverse curvature in an upward direction, the joining ends of the localized shell areas of the bow and stem portions having the simple transverse curvatures registering with each other to make substantially an angular junction defining a bulge for stabilizing the boat.

LLOYD G. BARKER. EDMUND N. TODD.