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The Details on Building a Cedar Strip Canoe

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Retired engineer. Amateur canoe builder, guitar builder, DIY pilgrim. Fisherman, hunter, camper.

I had previously written separate articles on each topic. I thought separate shorter articles were easier to search and read. This however apparently violates the platform policy on having an article series. I'm sorry to readers coming back to these articles if this compliant format is awkward and cumbersome.

The book I use for reference

The book I use for reference

Initial Thoughts

If you plan to build a canoe I would advise purchasing a book. It will contain much more information than I intend to provide here.

I decided to build another canoe of a different, more modern design. I chose the Freedom, which is a non-traditional shape with an efficient asymmetric hull. This means the hull has a sharper taper from the center toward the bow than it does from the center towards the stern. The slimmer forward profile helps increase speed while the wider aft section helps improve tracking. So goes the theory. My goal is build this canoe somewhat lighter than my last, although I still want it to be rugged enough for canoe camping and wilderness trips. I am thinking 55 lbs is a good target.

Lofting the Plans

Choosing a Design

So the first step was to choose a design, which I have done. I selected it from the various designs provided in Canoe Craft, though I will shorten it by about a foot.

The next step is to transfer the numbers in the tables onto paper so that the shape of the hull can be traced onto plywood for the forms. This process is called "lofting."

Lofting

I will describe what I did, but another description is available at the link below. On a large sheet of paper layout a grid of 2 inch X 2 inch squares. About 18 horizontal and 10 vertical. Mark a baseline and a centerline. The horizontal lines are water lines (WL) and the vertical lines are buttress (butt). Since the hull is symmetrical side to side only one half of the hull needs to be plotted to define it's shape. Once the first half of the hull is traced for a particular station, the outline plan for that station can be flipped about the vertical center line to trace the other half. Station lines tend to get crowded together near the center of the hull bottom so it would be a good idea to draw half of the stations on the right of the center line and the other half on the left. Or use more than one sheet of paper.

An example of a plot for station 8 is shown above. Measure from the center line along each horizontal water line for the "WL" values in the offset tables, then make a mark. Measure each vertical buttress line for the "butt" values in the offset tables, then make a mark. For the sheer draw a horizontal line at the distance from the baseline given in the table of heights. Then use the distance given in the table of half-breadths to mark the sheer along that line. The stem plots are created the same way by just using the WL gridlines.

Poster Board

My plan for the next step is to trace the half hulls on poster board to create templates for transferring the hull outlines to the particle board which will be used for the station molds. At the bottom of each station there needs to be a portion that will hold the station moulds above the strongback and which will allow the stations to be attached to the station blocks on the strongback. I plan to use about a 4-inch extension on each mold.

selecting design from plan view

selecting design from plan view

table of offsets for selected design

table of offsets for selected design

plotting table coordinates on grid

plotting table coordinates on grid

connecting dots

connecting dots

grid

grid

Making the Forms

Cutting Poster Boards

Scroll to Continue

Now the plans are lofted, or you have purchased plans, and you have hull outlines on a large sheet of paper. Since the cross-section of the hull is symmetrical, only half of the hull shape is needed for each form.

I cut three small windows in the plans, each about ¼” X 1/2: at the top of the vertical center line, at the end of the horizontal baseline, and at the intersection of those lines. Then I aligned the plan lines with the edge of a poster board and traced the hull outline onto the poster board using carbon paper. Take care not to allow the alignment to slip. You could use tacks or tape to hold the plan sheet to the poster board.

This results in a tracing of a half-hull cross-section. I repeated this for each outline, then, using scissors, I cut the half-hull poster boards. I was hoping the poster board edges would be square.

Cutting Out the Forms

Next, I purchased a 4' X 8' sheet of 5/8” particleboard. I had a sheet of OSB of similar thickness laying around, so I used that also. Using a carpenter's square, I drew a straight vertical line on the sheet of particle board, far enough away from its edge for the half-hull cardboard cut-out I was about to trace. I drew a line perpendicular to the vertical line four inches from the edge of the plywood. The side and bottom edges of the cut-out were lined up along the horizontal and vertical lines I drew.

Then I traced the outline, flipped it, and traced the opposite side. I repeated this step until all the cut-outs were traced onto the plywood. I marked each side of the hull outline where the sheer was located. I also drew a rectangular area below each outline between the edge of the plywood and the four-inch line. This would be the pedestal for the form, which is the area where the form is mounted to the station block. Then I drew a line from an inch below each sheer point to this rectangle.

I used a jigsaw to cut out the forms. I had a newer saw but the blade tended to wander around the curves so I switched to my old saw with a broken base plate. That worked much better but was slower. After each form was cut out, I smoothed the edges a bit with a sure form plane.

Mounting the Forms

Next, I drew the length of the strong back table (mine already had one from before) and mounted the station blocks (1-1/2 x 1-1/2 inch 12-inch long blocks). This design was for a 17-foot canoe but I wanted mine to be about 16 ft or maybe slightly less. The design called for the forms (or stations) to be spaced every 12 inches. I spaced mine every 11 inches.

First I drew a line in the center of the table perpendicular to the long center line then repeated it from there every 11 inches towards the bow and stern. The forms should be centered over each line, so the station blocks need to be mounted one-half of the form thickness from each of those lines. The station blocks should be on the bow or stern side of the forms depending on which side of the center.

I drilled clearance holes in the forms and mounted them to the station blocks, being careful to align the vertical pencil line on the form with the one on the strong back table center. A string stretched from end to end can help with alignment. The forms were attached with drywall screws.

Hull outlines every odds left, evens right

Hull outlines every odds left, evens right

Poster board cutouts

Poster board cutouts

Forms cut out

Forms cut out

Start to mount forms to strong back

Start to mount forms to strong back

Braided line strung from end to end for alignment

Braided line strung from end to end for alignment

Forms mounted

Forms mounted

Forms mounted and aligned

Forms mounted and aligned

Cutting and Milling the Strips

Selecting Wood

The construction of this canoe hull is a laminated core. The fiberglass and hardened epoxy from the outer laminate and the cedar form the core. This creates a very solid structure, something like human bone where the surface is dense and hard and the center is softer and porous. The wood does not necessarily need to be cedar, but lightweight is definitely a major consideration. The hull could be made entirely of hardwood such as ash but it would be extremely heavy. The type of wood traditionally used is western redcedar. I use what is readily available. For this canoe, I will use a mixture of ¾” rough sawn cedar boards I purchase at a big box store and 5/4” cedar deck planking. The deck planking was on sale at the time and I figured it was worth a try. The design of this canoe is not too radical and curvy so I thought the wider planking would be useable. Look for straight nonwarped boards with few knots.

How much wood do I need?

This is how I estimated:

  • Widest station is 53” measured along the contour of the hull
  • Assume a ¾” strip and loose 1/8 in for the bead and cove, so strips are .75 - .125 = .625

Full length strips needed : 53 / .625 = 84

I have 8 3-1/2” X 12’ X ¾” rough sawn cedar and 4 5-1/2 X 12’ X 1” cedar deck plank so:

  • Assume strips will be .2 and the saw kerf is .0625 (it will be more but this is an estimate) so
  • The 3- ½ boards yield (3.5 /.2625) *8= 106 strips
  • The 5 – ½ board yield (5.5 /.2625)*4 = 83strips
  • Since they are on 12 ft long. Multiply the number of strips by 0.75:
  • 106 x 0.75 = 79 and 83 x 0.75 = 62 (total 141 strips)

Cutting the wood

I set up my table saw with a feed table (saw horses actually) and a table to catch the strips coming off the saw. I used a thin kerf Diablo 7-1/4” circular saw blade. This is a great blade. Next the rip fence was adjusted to get the appropriate thickness. The first canoe I built was 15 ft long and I used 16 ft. boards. The kayak I built was 16.5 ft and I used a mix of 16ft boards and shorter boards. This boat is 16 ft. and will be constructed with the longest strip being 12 ft. This will required every strip to be butt or scarf jointed. Normally strips are 1/4” thick, but I decided to try to reduce a little weight by making them 0.2” thick. It is recommended that rough sawn lumber be planed to uniform thickness to ensure strips remain uniformly thick when ripped. I don’t have a planer so I make do and probably end up with more scrap. I check the thickness at each edge of test strips cut from scrap wood. Checking each edge thickness is a better way to tell the blade is square with the table than using a carpenters square. Some of the boards have a little warp and that makes some strips have thinner spots i.e. they will not have uniform thickness. This means more scrap also. I ran the strips through the saw by hand, without any additional jigs or spring fingers. In a few hours I had a big pile of strips ready to be milled.

Bead and Cove

I set up my router table in a similar fashion with feed and catch tables. The bits needed for the router are ¼’ bead and cove bits. I originally had a combo bead-and-cove bit with a ½” shank but halfway through the milling my cheap router burned up. I found another cheap router and table on sale at Lowe's for 40% off, but it had a ¼” collet. Luckily I had some ¼” shank bead and cove bits. I clamped homemade spring fingerboards onto the table and ran some test strips. This takes a while to get set up properly. I ran the bead on all strips first then the cove. The rotation of the bit was such that it wanted to pull the strips through. This is not recommended but I found that I get less shredding of the soft cedar this way. The fingerboards help keep the strips from becoming missiles.

More Thoughts on Cutting Strips

I ended up with lots of strips broken where knots were encountered and several that had thin spots, but I planned to do a lot of joining so some planks may have more than one joint. My concern is matching grain and color to get a pleasing appearance.

A circular saw with a guide clamped on also works well to cut strips. It can be easier to use than a table saw with long boards.

1 X 6 cedar boards

1 X 6 cedar boards

Feeding the table saw

Feeding the table saw

Checking the strip thickness

Checking the strip thickness

All the strips

All the strips

A pile of sawdust

A pile of sawdust

The bead and cove

The bead and cove

The fit of bead to cove

The fit of bead to cove

Combination 1/4' bead & cove router bit

Combination 1/4' bead & cove router bit

Making the Stems

Stems Form the Stern and Bow

Stems are laminated strips of wood that form the tip of the stern and bow. The inner stems are where the ends of the strips are stapled and glued, and tie the stripped hull together. The outer stems are glued on top to the inner stems and blended into the stripped hull with planes and sandpaper. They are usually made of hardwood and provide some protection for the soft strips and inner stems from collisions with shoreline obstacles.

For this canoe I made the inner stems with three ¼” strips, two cedar and one white pine. The outer stems were made with three ¼” strips, the outermost being maple and the others white pine.

Steaming the Stems

The stem strips must be steamed and clamped to the bow and stern forms and allowed to dry. Steaming the stems can seem a bit intimidating at first. I made a steamer out of a length of 4” PVC pipe and plugged the ends with a pieces of ¾’ particle board cut to fit with a hole saw. The bottom plug had a hole drilled in it to allow steam to enter the pipe. The source of steam was an old coffee pot with a short length of copper pipe replacing the bubbler. I filled the pot with water and set it atop a Coleman single burner backpacking stove. Once I had soaked the stem strips overnight in water I placed them in the PVC pipe, plugged the end and hung it from the rafters of my garage so that the pipe on the top of the coffee pot enter the hole in the plug. The secret to successful steam bending is lots of steam. I cranked the control of the stove all the way up to get the water boiling furiously. When I saw steam shooting from a tiny hole at the top of the PVC then I knew the steam volume was about right. About 30 -45 minutes is about right. The sides of the pipe will start to get soft.

Clamping the Stem Strips Onto the Forms

The hot strips, all six of them, are clamped onto the forms. Here is where I made a mistake with the forms. I only cut six 2” round holes in the forms, when I should have made them 1-1/2” and spaced them closer. Also I should have cut the first hole near the sharpest bend in the stems so that I could clamp the strips there first. This would have put less stress on the strips when bent since the ends have less distance between them and the form. But I made it work.

Combining the Stem Strips

Once the strips have been thoroughly dried, I glued them together and clamped them back on the forms. I used a mixture of epoxy, sanding dust and bits of fiberglass for the glue. The edge was first covered with plastic packing tape to prevent the strips from becoming permanently attached to the form. Packing tape was also used between the group of three inner strips and the group of three outer stems. This is a messy job and it is difficult to get all the strips aligned.

Shaping the Stems

After the epoxy glue mixture was sufficiently set I removed the clamps and cleaned off the dried excess glue with a sureform plane. I set aside the outer stems for later, and put the inner stems back on the stem form which I reattached to the strong-back table with the rest of the forms.

I attached one end of each stem to the form it butts against with a screw through the form into the stem and attached the other end with a screw through the stem into the stem form.

The stem must be now shaped. I drew a center guideline the length of the stem, and also a line 1/8” to the left and right of it. Using a plane, spoke shave, sureform plane or all three, the stem needs to be shaped to allow a glue-and-staple surface that will be flat where the strips will be attached. The area between the lines needs to be left flat after the shaping is finished. Near the top of the bow or stern the angle is sharper. The stem-to-strip interface should be as flat as possible to allow plenty of area for the surfaces to make contact.

I found that my bow stem form was off a little and I raised one end of the inner stem with a shim. I will continue to make small adjustments like this as the build progresses. It’s just part of building when you are neither an artist or carpenter, but just determined to build a useable canoe.


Shorter strips cut for stems

Shorter strips cut for stems

Stem strips soaking in the bathtub

Stem strips soaking in the bathtub

PVC pipe steamer

PVC pipe steamer

Steam escaping

Steam escaping

Stem strips glued and clamped to bow form

Stem strips glued and clamped to bow form

Stem strips glued and clamped to stern form

Stem strips glued and clamped to stern form

Inner and outer stems glued up

Inner and outer stems glued up

Stem marked for shaping

Stem marked for shaping

Stem beveled

Stem beveled

Checking to see that strip is flat against the stem

Checking to see that strip is flat against the stem

Stripping the Hull

When you attach the strips, you finally start to feel like you are making some progress. When you have attached the last strip and stand back to admire your work, it actually looks like a canoe. Don’t be fooled into thinking you are almost finished, however; you still have a lot of work to do.

Starter Strip

The first thing to do is to attach the starter strip at the sheer line mark you have on the forms. I attached that strip just below that mark because I want the canoe just a tad deeper than the design calls for. I’ll see how this works when it is done. This strip is cove side up so there is a channel to hold glue. My canoe is just under 16 ft. and my longest strips are 12 ft.

Scarf Joint Vs. Butt Joint

I scarf joined that first strip. A scarf joint is just a joint cut at a sharp angle. I soon decided just to use butt joints, which made stripping go much quicker. When attaching the first strip the tendency is to follow the sheer line, bending the strips to follow at the bow and stern. Too much of a bend here looks unnatural on the water. It is better to let the strip just droop to where it wants, attach it then add short filler strips at the bow and stern. I didn’t follow that advice, exactly. I thought that since this design does not have a very drastic curve at the ends, it would be ok to follow the sheer. Again I’ll have to wait and see if that was a mistake. Make sure the strips extend a little past the stems. This will be trimmed later.

Leveling the Strips

The starter strips need to be level across the canoe. I attached one side then attached the other side while laying a level between the right and left strips all along the length of the canoe. Now the rest of the strips can be attached. I found it best to attach only about 3 or 4 on each side then letting the glue dry.

Before you start randomly laying down strips I would advise that you sort them first. Discard the ones that have thin or very thick spots or are damaged in some way. Also it is a good idea to sort them by color so you can match them to make a natural colored/shaped design as the strips are applied.

Stripping the Sides of the Canoe

I have chosen to staple the strips to the forms but some builders use clamps and jigs to hold the strips down. I want to go fast and don’t mind all the tiny staple holes, I think it somehow looks more traditional. Like I have said before, I’m no artist. My objective is a functional boat. I use 9/16” staples and a cheap staple gun. In the book Canoecraft, the author suggests using a syringe to dispense a uniform amount of glue. I use Titebond II and apply it right out of the bottle. With a little practice the glue dispensed is fairly uniform. Titebond is waterproof but it is not necessary, since everything will be encapsulated in fiberglass and epoxy.

After the first few strips are glued and stapled, I go back with a wet cloth and wipe up the excess glue from the inside and outside. It can be a pain to remove once it has dried. I then check that all the bead and cove joints are mating the best possible. My strips are not perfect so the mating surfaces are not always perfectly matched. Oh well. I try to press the strips together between the stapled points on forms, then if there is some movement, masking tape is used to hold them together.

Rounding the Corner

The sides of the canoe are fairly easy to strip. It gets more difficult to attach strips where the hull rounds the bilge from the sides to the bottom. The strips not only need to be laid along that curve on the forms, they become twisted since the bow and stern stems are not following the same curve. You may eventually get to a point where staples just won’t hold the strips down. The twisting wants to pull out the staples. This is where the clamps and jigs become handy. The butt joints will sometimes want to twist out of shape also, so clamping a short piece of scrap strip, covered with tape, on the hull inside and outside over the joint will hold it in place. I didn’t worry too much about cracks of dips or butt joints, I’ll be doing a lot of patching. Oh well, I’m hoping to get this boat done in 2 more months to use on my Canadian fishing trip.

Finishing the Bottom One Side at a Time

Once you round the bilge, you want to continue to attach strips to just one side until they cross the centerline of the forms. They can then be cut along the center line with a utility knife. Next the other side of the bottom can be stripped. However these strips must be cut at angles on the ends where they butt against the center line.

Some other observations during stripping: I have a tendency to put my tools on the strongback between the forms and I spend a lot of time walking the length of the canoe looking for them. I advise resisting that urge and having a table to set them on. I should have taken more time sorting strips, I have a lot left over. You can make some cool effect with the natural color in cedar. My forms are not perfect which cause a few flat spots in the hull. With the previous boats this happened also, but it seemed that when the staples are pulled the hull sprung out a little, making these areas disappear.

A Note on Clamps

You will need lots of them. Mostly I used hand spring clamps and 4 inch C-clamps as you can see in the photos. If you don't have many then get more before you start the project. I did need a few C-clamps larger than 4 inches. For the spring clamps I recommend the heavy duty 6 inch size.

Leveling strips left and right

Leveling strips left and right

View of strips stapled to stem

View of strips stapled to stem

A few strips attached

A few strips attached

Using a spring clamp at a butt joint

Using a spring clamp at a butt joint

A scrap strip piece clamped at a butt joint

A scrap strip piece clamped at a butt joint

Some creative clamping

Some creative clamping