US20090199756A1

US20090199756A1 - Wooden watercraft hull construction

Info

Publication number: US20090199756A1
Application number: US12/367,126
Authority: US
Inventors: Robert J. E. Von Bitter
Original assignee: Heirloom Canoes
Current assignee: Heirloom Canoes
Priority date: 2008-02-08
Filing date: 2009-02-06
Publication date: 2009-08-13
Also published as: CA2620693A1

Abstract

A wooden hull construction for a watercraft, particularly a canoe, includes a multiplicity of boards, each board individually secured to adjacent boards while maintaining parallel alignment. In an aspect of the hull construction wherein there is a single layer of boards, the boards are secured together in parallel alignment along their lateral edges with adhesive. In multiple-layer hull construction aspects, each layer of parallel hull boards is secured to an adjacent layer with board edge seams substantially offset from the board edge seams of the adjacent layer. Individual boards are secured directly to adjacent boards in the same layer or to boards in the adjacent layer, or both. The hull boards are aligned substantially transversely, i.e., gunwale to gunwale, of the watercraft.

Description

BACKGROUND OF THE INVENTION

The present application relates generally to watercraft and, more specifically, to a wooden watercraft hull construction.
Before the mid-1800's canoes were made of birch bark and were extremely light but not durable, or, they were made of dugout logs and were more durable but very heavy.
Many wooden canoe designs were made in Ontario's Trent Valley in the latter half of the 19th Century. These “all-wood” canoes sought to replace birch bark and dugout watercraft and were made with strips of wood most often aligned with the long axis of the canoe. These strips or boards were fitted together to form the shape of the hull. These strips were held to an underlying frame structure, running principally across the length of the strips or boards, with clinched nails (normally copper). Fitting was done with such skill that only varnish was needed to be watertight. Many new canoe designs were made during this period including “rib and batten” and “flush metal batten”.
Three principal designs resulted in the Cedar Rib shown in Canadian patent 10,063, dated May 1879, the Longitudinal Strip shown in Canadian Patent 32,701 dated 1883 and the Double-cedar shown in Canadian patent 1,252 dated December 1871.
The objectives remained that the canoe be easily made, watertight, serviceable (both in the field and in the shop) and be light in weight.
John Stephenson or Thomas Gordon invented the first board canoe which had two or three wide (i.e., width greater than six inches) boards running lengthwise which were secured over steam bent hardwood ribs by thousands of copper nails. To stop water from leaking in along the butt-jointed edges interior wooden battens were fitted over the board edges, in sections between the cross-ribs. This design became known as “Rib and Batten” (or Board and Batten) and was reported to be used exclusively in the construction of wideboard canoes. This type of wideboard canoe was relatively easy to build and was reasonably light. However, when the wide boards expanded in moisture and dried out large cracks would appear in the wideboards, making it difficult to keep watertight.
In 1871, Daniel Herald is reported to have built a better canoe with his “Double-Cedar” design which is shown in Canadian patent 1,252, dated December 1871. The Double-Cedar design was comprised of one layer of long boards running the length of the canoe on the exterior of the hull. A second layer of long boards or planks ran perpendicular to the length (i.e., gunwale to gunwale) on the interior. The two layers were fastened to with thousands of clinched copper nails. A layer of canvas impregnated with lead (termed “doped canvas”) was sandwiched in between the cedar layers. The canvas provided an extra measure of watertightness. It is understood that the canvas was required to prevent leakage between the strips, particularly when the boards of the canoe dried and left small gaps at the edges of the strips. This design was watertight with a smooth interior but was heavy because of the double layer of cedar, the substantial hull structure of ribs and the leaded canvas. Furthermore, once the integrity of the canvas was compromised the canoe could not be kept watertight since the canvas could not be replaced without taking the whole boat apart. The Herald double-cedar canoe was a strong design but was less satisfactory in terms of serviceability and lightness.
By the 1870's, builders of board canoes started to use narrower cedar strips which are much less susceptible to shrinkage damage and gaps when compared to wide board varieties.
A second design using narrower strips was invented by John Stephenson (the “Rib Canoe”) in 1878 for which he received a patent in May of 1879 (Canadian patent 10,063). This canoe was made of narrow cedar strips that ran gunwale to gunwale and which were fitted together with machined tongue and groove edges. Hardwood stringers (narrow hardwood strips that ran the length of the boat), the keel and a keelson all ran the length of the boat and provided both lateral support and a hull structure for this extremely light and strong craft. These canoes were extremely time consuming to make and even harder to service. Cedar Rib canoes were made on a specialized form in which the strips would sit in a kiln and tightened a little bit each day until it was totally kiln dried, at which point the assembled hull had to be totally disassembled to get it off the form and then reassembled. If, during use, a Cedar Rib strip became damaged and had to be repaired it was virtually impossible to fix because the tongue and groove edges on either side of board prevented a new piece from being inserted between. This canoe was strong, light and watertight but was less than satisfactory for general use in terms of ease of construction and serviceability.
Another canoe invented by Stephenson involved narrow parallel cedar strips running longitudinally with the length of the craft. To give the canoe shape and strength, the cedar strips were fastened to hardwood structural ribs which had been first bent over a canoe form. Rather than tongue and groove edges, these canoes had simpler rabitted (or shiplap) board edges. Despite the fact that Stephenson's 1883 patent diagram (Canadian Patent 32,701) shows the canoe with tongue and grooved edges, it seems to have almost exclusively been made with rabitted/shiplap edges. This Longitudinal Strip canoe design became the most common method of all-wood canoe construction as it represented a reasonable balance between water tightness, serviceability and weight.
Other innovations occurred in the wider board designs. One was the Flush Batten construction method in which the inside half of the board thickness at each edge was rabitted and fitted with a flush wood batten which ran the length of the board. These were then secured to the internal lateral ribs or frames. A variation (the Flush-metal Batten design) involved small grooves made near the board edges in which a metal band was inserted. In both the Flush Batten or Flush Metal Batten methods, securing the planking boards to the ribs kept the battens tight and thus helped to keep the boat watertight. Flush Metal Batten and Rib and Batten construction methods were used for wideboard canoes for many decades but were never as common as Longitudinal Strip.
Cedar-canvas canoes (reportedly first invented in the 1880's and first patented in 1905), eventually became much more popular than all-wood varieties. These canoes relied on a canvas membrane for water tightness and, therefore, the edges of the longitudinal cedar planking only had to butt jointed. They could be made and repaired inexpensively. Cedar canvas canoes were generally lighter than all-wood varieties. More rot resistant cedar ribs, instead of hardwood ribs were used so they were easier to maintain. If a piece of planking needed to be replaced, it is much easier to do so as on cedar canvas canoes the planking doesn't need to be fitted, only butted together (butt jointed). Cedar canvas canoes are relatively common today because they are light, reasonably easy to build and maintain, and have warmth to paddle and beauty compared to more modern aluminum, fiberglass or Kevlar™ canoes.

SUMMARY OF THE INVENTION

According to an aspect of the present disclosure, a watercraft is provided. The watercraft may include a hull construction comprising a layer of wood strips aligned transversely of the length of the watercraft wherein the strips are edge-bonded directly to each other in an abutting parallel relationship to form the hull.
Conveniently, such as watercraft includes no substantial restraint on expansion or contraction in the hull construction in the direction of the length of the watercraft due to varying moisture levels in the wood strips. Any additional components of the watercraft may be secured to the hull with means providing for relative movement between the additional components and the hull in the direction of the length of the watercraft. Such additional components include longitudinal strips aligned substantially to the length of the watercraft and are principally wood and may include one or more of a gunwale, a keel, a keelson and a plurality of interior or exterior stringers.
According to another aspect of the present disclosure, a watercraft is provided. The watercraft includes a hull construction comprising an outer and an inner layer of wood strips, the strips being aligned transversely of the length of the watercraft to form the hull wherein the strips are secured directly to each other in a parallel relationship and the strips of the outer layer overlap the strips of the inner layer. The wood strips in each layer may be in an abutting parallel relationship and the wood strips in one layer may be secured to directly to the wood strips in the other layer. The watercraft may have continuous layers, thereby providing a smooth exterior and a smooth interior surface. The strips in the layers are not necessarily secured to abutting strips within each of the two layers.
Other aspects and features of the present invention will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the drawings, which show by way of example, embodiments of the invention, and in which:

FIG. 1 illustrates, in a plan view, a canoe in its fully assembled condition ready for in-water use, according to an embodiment;

FIG. 2 illustrates, in an elevation view, the embodiment of FIG. 1;

FIG. 3 illustrates, in a partial perspective view, a double layer hull plank configuration, according to an embodiment;

FIG. 4 illustrates, in a partial plan view, a hull construction at a gunwale taken along line A in FIG. 2;

FIG. 5 illustrates, in a side cross-sectional view, the gunwale illustrated in FIG. 4 taken along line B-B in FIG. 1;

FIG. 6 illustrates, in the view of FIG. 4, splined plank assembly;

FIG. 7 illustrates, in the view of FIG. 4, ship-lap plank assembly;

FIG. 8 illustrates, in the view of FIG. 4, tongue and groove plank assembly;

FIG. 9 illustrates, in the view of FIG. 4, beveled plank assembly;

FIG. 10 illustrates, in the view of FIG. 4, cove plank assembly;

FIG. 11 illustrates, in a cross-sectional view, longitudinal floating connections of a keelson and keel for the embodiment of FIG. 1;

FIG. 12 illustrates, in a view familiar from FIG. 3, a single layer hull construction of an embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A watercraft 1 embodying an aspect of the invention is shown in FIG. 1 in the form of a wood canoe.
A hull construction 4 embodying an aspect of the invention preferably includes an inner layer 8 and an outer layer 9 of abutting planks 5. Each plank runs parallel to the others and is arranged transversely of the length of the canoe from bow 2 to stern 3 as shown in FIGS. 1 and 2.
Preferably planks 5 are of equal width, as shown in FIGS. 1 and 2, and the layers are offset from each other along the length of the canoe, as illustrated as an offset 6 in FIG. 1, by ½ of the plank width so that the canoe 1 has a smooth inner surface 7 and a smooth outer surface 10.
The planks of inner layer 8 are secured directly to the planks of outer layer 9 by an array of fasteners 11, which may be screws or clinched nails as in FIG. 2. Planks 5 are thus retained in a parallel abutting relationship between and among both inner layer 8 and outer layer 9.
The canoe 1 includes a gunwale 12 shown in the form of a longitudinal member affixed to the outer layer 9, also known as an “outwale”. Additionally, the canoe 1 may include an inner gunwale member (shown in FIG. 12), also known as an “inwale”, affixed to the inner layer 8.
Inner longitudinally aligned stringers 14 and a keelson 15 are preferably affixed inside the hull.
Outer longitudinally aligned stringers 16 and a keel member 17 may be affixed to the outside of the hull.
FIG. 3 shows an enhanced perspective view of a portion of the hull construction 4 comprising four abutting planks 5 with the inner and outer layers 8 and 9 being secured to each other by fastener array 11. Array 11 includes a pair of rows of fasteners 17 adjacent the outer plank edges and another pair of fastener rows 18 adjacent the inner plank edges and thus located more centrally of the inner planks 5.
FIG. 4 shows a partial plan view of the hull construction 4 at the gunwale taken along line A in FIG. 2. Fastener 21 secures outwale 12 preferably to outer layer 9 as its threaded end 22 engages with plank 5. Preferably, stopper 23 is included to guide fastener 21 as it is secured in place. Nut 24 engages with the threaded end of fastener 21 and draws gunwale 12 into contact with outer surface 10 along direction 27.
Preferably, fastener 21 lies wholly within a larger access slot 25 to provide a smooth finish whereas fastener 21 passes through expansion slot 26 in gunwale 12 so that some relative movement is accommodated between gunwale 12 and hull construction 4 in the longitudinal direction 28.
FIG. 5 shows partial cross-section of the fastener 21 of FIG. 4 taken along line B-B in FIG. 1. FIG. 5 depicts fastener 21 as a threaded machine screw of known configuration with its head 29 secured inside hull construction 4, its shaft 30 passing through expansion slot 26 and its threaded nut 24 engaged in access slot 25.
The whole of gunwale 12 is preferably secured to the hull construction 4 with a plurality of expansion joints 38 of the type shown in FIGS. 4 and 5 as at 38 in FIGS. 1 and 2.
Similarly, any inner or outer stringers 14, the keelson 15 and the keel 16 are preferably secured to the hull construction with expansion joints (FIGS. 4 and 5) as at 36, 35 and 37 respectively.
As can be seen, the addition of longitudinal members provides for and does not substantially impede the expansion or contraction of the hull construction 4 in the longitudinal direction while assisting in the required structure.
Planks 5 my be fitted together in their respective layers 8 and 9 with splines 30 as illustrated in FIG. 6, with ship-lap joints 33 as illustrated in FIG. 7, with tongue and groove joints 31 as illustrated in FIG. 8, with bevel joins 34 as illustrated in FIG. 9 or with curve matched joins 32 as illustrated in FIG. 10 or in other known manners.
At FIG. 11 keelson 15 and keel 17 may be secured opposite each other across hull construction 4 and fasteners 21 secured to a single layer or, alternatively, through-bolts as at 39, which provide for attachment along direction 40 while providing for individual expansion joints 41 and 42 opposite each other.
Expansion joints 41 and 42 may be constructed without access slot 25 as at 43.
An aspect of an alternative embodiment of the hull construction is shown in FIG. 12 which employs a single layer of transversely arranged planks 43. Planks 43 are secured directly to each other along their respective lengths as at 44 to form the hull construction 4. Preferably, planks 43 are secured by a strong and waterproof adhesive applied to their long edges 44 and bonded throughout their length.
Gunwales, stringers, a keelson and a keel may be added to this embodiment, FIG. 12, in the same fashion as with the main preferred embodiment.
A canoe hull construction has been described with one or more layers of wood planks or strips running transversely of the craft from gunwale to gunwale, where the wood planks are secured substantially to each other in an overlapped fashion or with waterproof glue and gunwales and other structural members are attached to the hull construction by fasteners, such as bolt or screws, through expansion slots aligned generally lengthwise to the craft and across the wood hull planks. Conveniently, aspects of the hull construction allow the wood hull planks and the structural members to expand and contract independently in their different directions, thereby significantly reducing the occurrence of cracks in the hull.
Advantageously, according to various aspects, the hull construction is extremely strong and light, thereby harnessing the strength inherent in steam bent wood in which the grain is bent to the curving axis of the part and resulting in much greater strength by avoiding the cross-grain weakness to form a structurally complete hull substantially independent of internal ribs, frames or stringers.
Additional aspects of the hull construction allow the wood to expand and contract as it needs to both the small amount along both the length of the grain and the larger amount along the width of the grain without damaging the craft and without causing leaks. Planks are secured to each other in one or two layers and may expand and contract across their grain with no opposing forces that would prevent or restrict this expansion and contraction.
Additional aspects of the hull construction resist, in extremely dry conditions, tearing of the hull board edges and leaking caused by planking drying in a direction transverse to other hull members and structural elements.
Advantageously, according to various aspects, the hull boards are secured relative to one another, thereby reducing the formation of gaps between the boards so that the craft may maintain watertightness.
Additional aspects of the hull construction, wherein the board edges overlap one another, provide a smooth interior surface and continuous backing to each seam.
Advantageously, according to various aspects, the hull construction is readily serviceable and may be repaired without taking the whole boat apart in which a new replacement piece can be steam bent over the canoe and fitted and replaced relatively quickly and with relative ease.
In additional aspects of the hull construction, the watercraft hull construction reduces effort and expense involved in construction and allowances are made for building the watercraft hull in parts (½'s or ‘A’s) so that the watercraft hull can be readily removed from a mold and adapted to various lengths with ease by assembly plank by plank along the length of the craft.
As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter shown in the accompanying description and drawings is to be interpreted as illustrative and not in a limiting sense.

Claims

1. A watercraft including a hull construction comprising:

a layer of wood strips aligned transversely of the length of the watercraft wherein said strips are edge-bonded directly to each other in an abutting parallel relationship to form said hull.

2. A watercraft as claimed in claim 1 wherein the watercraft provides no substantial restraint on expansion or contraction in said hull construction in the direction of the length of said watercraft due to varying moisture levels in the wood strips.

3. A watercraft as claimed in claim 2 wherein additional components of the watercraft are secured to the hull with means providing for relative movement between said additional components and said hull in the direction of in the direction of the length of said watercraft.

4. A watercraft as claimed in claim 3 wherein said additional components include longitudinal strips aligned substantially to the length of the watercraft.

5. A watercraft as claimed in claim 4 wherein said longitudinal strips are wood.

6. A watercraft as claimed in claim 5 wherein said longitudinal wood strips include one or more of a gunwale, a keel, a keelson and a plurality of interior or exterior stringers.

7. A watercraft as claimed in claim 6 wherein said gunwale comprises an outwale and an inwale.

8. A watercraft including a hull construction comprising:

an outer and an inner layer of wood strips said strips being aligned transversely of the length of the watercraft to form said hull wherein:

a. said strips are secured directly to each other in a parallel relationship, and,

b. the strips of the outer layer overlap the strips of the inner layer.

9. A watercraft as claimed in claim 8 wherein said wood strips in each said layer are in an abutting parallel relationship.

10. A watercraft as claimed in claim 9 wherein said wood strips in one said layer are secured to directly to said wood strips in the other said layer.

11. A watercraft as claimed in claim 10 wherein said layers are continuous.

12. A watercraft as claimed in claim 11 wherein said strips in said layers are not secured to abutting strips within said layer.

13. A watercraft as claimed in claims 10 wherein the watercraft provides no substantial restraint on expansion or contraction in said hull construction in the direction of the length of said watercraft due to varying moisture levels in the wood strips.

14. A watercraft as claimed in claim 13 wherein additional components of the watercraft are secured to the hull with means providing for relative movement between said additional components and said hull in the direction of in the direction of the length of said watercraft.

15. A watercraft as claimed in claim 14 wherein said additional components include longitudinal strips aligned substantially to the length of the watercraft.

16. A watercraft as claimed in claim 15 wherein said longitudinal strips are wood.

17. A watercraft as claimed in claim 16 wherein said longitudinal wood strips include one or more of a gunwale, a keel, a keelson and a plurality of interior or exterior stringers.

18. A watercraft as claimed in claim 17 wherein said gunwale comprises an outwale and an inwale.