Introduction Welcome to my blog on boatbuilding. I will talk about my methods, designs and the boats I have built. The earliest boats were canoes. Because of their simplicity and low cost, they were a good learning experience. This page is about the early canoes when I was developing my design skills; just click on the sub-headings above for the other pages.
Boat Construction I like to build boats and prefer a bit of control over boat design, so most of them are my own designs. I like boats that are stylish, light too as I have to car-top, and at the same time easy, cheap and quick to make. Before I started I explored various plans and construction methods. The traditional methods using hand-cut lumber, copper nails etc., were out of the question; the boat would be too heavy to car-top even if I had the building skills.
I looked at the -plank and-batten, ply-with-chine-logs and stitch-and-glue (S&G) methods. S&G is a neat idea, the boat is light and can be built without building an elaborate jig. There are some snags, however. It is necessary to cut the planks accurately and there lots holes to drill and copper stitches that have to be inserted and tightened, and on a varnished hull they show. The seams between the planks must be reinforced by epoxy fillets and glass tape; sanding the fillets is messy and hard work. The advantages of epoxy include its gap-filling and water-proof properties, but it's costly, and the fiber glass material is not pleasant to handle.
I combine S&G with the older plywood and chine log method. Chines are the longitudinal joints between planks, and a chine log is simply a wooden batten that reinforces the joint. I use very light chine logs which, together with the inwales (the inner portion of the gunwale or gunnel) are glued to the sheer planks while they are flat. That allows me to use simple, cheap, water-cleanup glue because I can get the perfect joint such glue demands. These sheer assemblies are then bent, usually around one or two crude forms, and glued together at each end for a canoe, or glued to a transom board at the stern for other boat types. It is then a simple matter to place the plywood bottom over the sheers, mark the outline and cut it to shape, and glue it in place. I use epoxy for this joint because it is exposed to water below the waterline.
If the hull is to have 5 planks the bottom also has chine logs glued to it while it is flat, same as the sheers. The last planks are the bilge planks, and are epoxied in position, because these joints are exposed to water below the waterline.
Whether the hull has a flat bottom or has 5 planks with bilge planks, gluing the last planks with epoxy also takes advantage of its gap-filling properties, since it is more difficult to fit these joins perfectly, with their 3-dimensional curves and angles.
I try to design so things are as simple as possible, parts follow natural bends, parts have straight edges as far as possible so there are no complicated curves that have to be traced and cut carefully, and so forth.
Designing: making a Start My first canoe design was very narrow with a Vee-bottom. Pretty, but useless; it was so unstable I had difficulty keeping it from flipping over. I figured there was too much buoyancy below the seat so I cut out the Vee bottom and put in a flat one, which helped a bit. You can do that sort of thing with a wooden boat! I continued to make changes, using the boat as a test bed for design ideas. I made the bottom still wider looking for more stability, and finally cut off part of the pointed stern and put in a transom to increase the width at the stern. That made it feel more stable, but it still wasn't very good and by this time it was getting a bit scrappy so I cut it up.
Better, But Still No Cigar! The next canoe was built with a transom and extra thick gunnels. That allowed me to build it without thwarts. I had an idea that, if I wanted to carry several canoes on top of a car, I could carry them in a pile like stacking chairs.
Gunnels must be firmly attached to the transom, which is usually done using knees inside the boat. However, that would have made it impossible to stack another canoe inside, so I extended the gunnels past the transom and put in an overhanging shelf. This is not easy to see in the picture, but the color change where the bottom joins the transom is easily seen so the shelf can be identified.
It worked a bit better than the first canoe but the transom caused a lot of noisy turbulence and drag when it was moving through the water, and it still felt unstable. I had not realized at this stage in the development of my design skills that the bottom must rise above the surface where it meets the transom.
Dora This is Dora, the canoe I built in 2008. She is 3.7m long, weighs 10 kg, and is very fast. She is constructed of marine plywood, cedar and pine. A young lady took one look at her and called her "adorable" so she was called Dora from that time. She has a narrower bottom than the previous canoes, just wide enough to sit on, but the hull flares out and up so it is much wider at the waterline. That allows her to sit as low as possible but still have plenty of beam at the waterline. Also, her hull curves up at each end (rocker) which reduces buoyancy at the ends, allowing her to sit lower in the water. This stiffens her resistance to rolling.
She is very easy to paddle and runs straight. A bit too straight actually; the next canoe will have a bit more rocker. She has a tendency to turn up wind. I added a skeg which helped, but the next canoe will have a slightly higher bow than stern to help prevent the windsock effect.
The Building of Dora I built Dora from a single sheet of 3 mm thick marine plywood for the sheer (side) and bilge planks, with a bottom cut from a quarter sheet 0f 6 mm plywood - sold by my local harware store as project panels. Viewed from the end she has a five-sided outline, with the bilge planks joining the sheer planks to the bottom plank.
Rather than using glass fiber tape and epoxy, I reinforced the long joints between the planks with cedar chine logs. Most of the wood and ply parts bent easily around the shape of the hull, but the top edge, or gunnel, was too thick to bend in one piece so I laminated it from alternate strips of cedar and pine. The contrasting colors add to the attractive appearance of the finished boat.
Cutting Out the Plywood I made a special table for cutting out and assembling large plywood panels. It's a simple wood frame 12 foot (3.6 m) long, 32" (0.8 m) wide, and the top is cut from a single sheet of 2" (50 mm) thick insulating foam. To cut the sheet of plywood I lay it on the foam, which has a non-slip finish, and cut using a hand-held circular power saw set for shallow cutting depth. The foam protects the table from the saw blade, reduces wear on the blade, and it was cheap! Any large table can be used of course.
In the picture the panels for the sheer planks have been cut from the plywood sheet. The plywood sheet is too short to cut out a sheer plank in one piece, so I had to glue an extension to each sheer plank; the extensions are on the right side of the table in the photograph. The diagram below shows how the plywood sheet and project panel were cut. The small parts from inside the plywood sheet outline are glued to the long pieces to make up the length of the boat.
Finishing the Sheer Planks After I glued the sheer planks and their extensions together, I trimmed the top edge to make a smooth, graceful curve which would become the top of the finished boat. I used strips of wood, held in place by heavy objects like power tools so I could draw the cutting line. I was very careful to make the sheer planks exact mirror images, so the boat was symmetrical!
In this picture, I glued the reinforcing strips of cedar along the edges of the shaped sheer plank. The top strip - the inwale - has already been glued and the bottom edge - the chine log - is clamped while the glue sets. Although not visible in the picture, the inwale was rabbeted to the depth of the ply thickness, thus hiding the edge of the plywood.
A boat builder never has enough clamps, especially a beginner amateur like myself, so I made some clamps from plastic plumbing pipe, slit lengthwise and cut into short lengths, which can be seen in the image; there were enough to glue and clamp both sheer planks at the same time.
The Building Forms The next step was to bend the sheer planks to shape, and joint them together at the stems. The stems of a canoe are the bow and the stern.
I cut out 2 station molds and fastened them together with a piece of wood as shown in the picture. In a design drawing of a boat, stations define the cross-sectional shape of the hull; the five-sided shape is visible in the image. The 2 stems can also be seem between the forms: they look like short hockey sticks and were cut from 3/8" (about 9 mm) thick plywood.
Most boat builders would have extended the piece of wood joining the forms, called a strong back, all the way to the stems whcih are the ends of the hull. I wish I had done that; it would have kept the boat straight during construction. Without the full-length strong back I spent a lot of time checking the boat was still straight.
Oh! You're building a Boat! Here I reached the stage when visitors could see what I was doing!
I have bent the 2 sheer planks around the frames and pulled them together at the ends, sandwiching the plywood stems, which can be seen sticking up above the planks. This picture was taken during the dry run, without glue. I found the duct tape held the planks together well enough, but I needed to ensure the planks came together correctly after gluing so I drilled small holes through the stems and inserted thin dowels to keep everything in place. The dowels are actually bamboo barbecuing sticks and did the job perfectly; I just trimmed them off level with the plywood when the glue had set.
Attaching The Bottom I took this picture after adding the bottom. I made the bottom plank by cutting the 2' x 4' "project panel" into 3 pieces and gluing them together to get a longer, pointed plank which I trimmed roughly to shape. Then I glued reinforcing strips of cedar along the edges - in the picture as they are underneath.
The bottom was glued and screwed to the plywood stems, one at each end. The stems were too thin to provide a rigid support for the bottom so it was reinforced by 2 pieces of pine called stem cheeks, shown here glued and clamped to either side of the stem. Both stems were treated in the same way. The boat was still quite delicate and "floppy" at this stage, and I was really starting to appreciate the reason why most boat builders use a full-length strongback.
Getting Ready For The Bilge Planks The bilge planks fill in the long gaps between the bottom and the sheer planks. They also add a great deal of strength. It was important to ensure they were really solidly attached, so the glue joints for the bilge planks are the most important on the entire boat. Not only do they provide most of the boat's strength and stiffness, but they get soaked with water while the boat is in the water, unlike any of the other joints, and they also support the weight of the paddler!
So the first task was to cut 4 long bevels, along the upper edges of the sheer planks and both edges of the bottom plank, to provide plenty of width for the glue. These bevels had to be at the correct angle so the bilge planks would rest snugly on them instead of just touching along an edge. The bevel angle changes continuously so these are rolling bevels.
In the picture I am using a power planer to cut the bevels. I modified it by replacing the aluminum base plate with a much wider plywood one, which bridges the gap between the bottom and sheer plank and keeps the tool at the correct angle. This was noisy and dusty, but didn't take very long.
The Bilge Planks I took a lot of care over this stage; these were the most complicated shaped pieces on the entire boat and a mistake meant having to buy another sheet of (expensive) marine plywood. An advantage of this building method over the stitch and glue method is the plywood can simply be placed in position and the plank shape marked for cutting, ensuring no errors.
Way back when I cut the sheer planks from the plywood sheet, there was a big piece of plywood left over, and the bilge planks were cut from this. The bilge planks weren't long enough since the plywood comes in 8 foot (2.44 m) lengths and I was making a 12 foot (3.6 m) long boat, so I needed to cut out 4 triangular extension pieces to glue on each end of both bilge planks.
The Gunwales "Wale" is an old nautical term meaning plank. Also called gunnels, the gunwales are wood strips that reinforce and finish the top edges of the sheer planks. Each consists of an inwale which attaches inside the sheer plank and an outwale. Finally it was time for the boat to be turned right side up. I suppose I should have mentioned sooner that this boat was built upside-down!
In this picture I have glued and clamped the last cedar strip to the top edge of the sheer plank, along the outside. This strip is called an outwale, and is one of 3 strips making up each gunnel, including the inwale which was added while the sheer planks were still flat. The gunnel, sometimes called the gunwale (wale is an old word meaning plank) runs along the top edge of the sheer plank to stiffen and strengthen it.
Note that the little decks at each end have already been added, which made clamping the gunnel strips at the ends a bit more difficult. I could have added the decks after, but doing the job this way left a furniture quality joint between the deck and the outwale. I don't think I could have cut the decks to fit that accurately after the gunnels were finished. Swings and roundabouts . . .
Dora's Secrets This picture was taken while the gunnels were being glued and clamped. It shows the details of one of the small decks from the underside. The decks are plywood, supported on a Tee-shaped frame. In the picture the clamps holding the outwale strips are still in place.
The finishing touches included the varnishing of the gunnels and decks, building and finishing of the seat, sealing, priming and final painting. Another of Dora's secrets is the paint. Apart from the varnish, which was a regular boat varnish, I used regular house paint on the hull! Semi-gloss gave a good finish, but did not reveal all the little irregularities that a gloss paint would have done.
Final secret: all the varnish and paint were water-based for easy clean-up and minimum environmental impact. heading into her 6th year, Dora is holding up fine! I think I'll give her bright work another coat of varnish some time soon, as I used the wrong kind. It was interior varnish, so it will need a protective coat of exterior varnish to prevent it being damaged by ultra-violet light.
Despite the light weight of Dora, I could have built her lighter. The seat is a bit fancy for such a simple boat, I don't think I needed to use thicker plywood for the bottom. I certainly didn't need to add the reinforcing strips across the bottom which can be seen forward of the seat in the picture of Dora; since all my weight is always on the seat the bottom merely holds up the weight of my legs. But I still have a lot to learn . . .