STRIP BUILDING TIPS
Based on feedback from our customers, here are a few tips on setting up the strong back and mold stations, stripping, fiberglassing, and finishing. It is worthwhile spending the time to get the mold right, as it will determine the final shape of your canoe. For more detailed information get “Canoecraft” or “Building a Strip Canoe” from Noah’s or check online.
You will need 2 sheets of 3\4” plywood, or particle board. Try to get them without warps or curves and, store them flat. Cut and, assemble a 12” x 6” box beam, x length from your plans. Use 2’ butt blocks to join the 8’ sections. Put a string line along the edge of the 16’ pieces before screwing them together to be sure it is perfectly straight and again on the top and sides of the box when assembled. You can use lumber for the beam but it should be old and dry, do not use new lumber. The top surface should be straight, level, and stable, anything else could get you a funny-looking canoe.
Build 2 legs and feet to support the strong back at a comfortable working height, the top of the highest mold station should be about chest level. Use a spirit level and shims to trim lengthwise and crosswise. If possible fasten the feet to the floor. The strong back needs to be straight and level when assembling the mold stations, but may be moved after you start the planking.
Use a string to mark a centerline on the top of the strongback. Mark a point on the centerline ½ way from the ends of the strongback. Mark 12” intervals from the center, one for each station, and use a square to mark lines perpendicular to the centerline. Screw a 1” x 2”x 12” piece of wood to the strongback at each line.
TRANSFERRING THE PAPER MOLD STATIONS TO PLYWOOD.
You will need 2 or 3 sheets of 5/8” plywood or particle board for the station molds depending on canoe size. Lay the 4’ x 4’ paper plan sheet out on a flat surface, and iron out the fold creases.
Starting with the largest station, tape the plan to the plywood so the bottom of the station is lined up with one edge of the plywood. Use a carpenter’s square to be sure the centerline is perpendicular to the plywood edge, use 2 tacks at the top of the paper plan to hold it in place. Slide carbon paper under the plan, ink side down, and trace the station line and centerline onto the plywood.
Alternately drive 1 1/4” finishing nails through the station lines into the particle board at 3” intervals. Be sure the nails are straight and perpendicular to the plywood, and pull the paper plan up through the nails. Bend a flexible wood or plastic baton around the outside of the nails, holding one end against the first nail with a spring clamp. The baton should describe a fair curve with no kinks or dips just touching the outside of each nail, mark the inside of the baton with a pencil, and also mark the centerline. This is the better method as it will compensate for paper irregularities and shaky hands.
CUTTING THE MOLD STATIONS:
A band saw is best but a jigsaw will work as long as the blade is straight and square. Try to cut as close as possible along the outside of the line, if you dip below the line you will have to add a piece back. Trim high spots back to the line, and be sure the edge is square with the face, not beveled or rounded. If you have a belt sander clamp it on the edge and square to a table so you can move the mold station on the sander to trim. Place the cut and trimmed station on the paper pattern, they should match. Except for the centre station, there are 2 of each so use the first one to pattern the second. Or, you can make it easy on yourself and get a set of CNC-cut molds from Noah’s.
ASSEMBLING THE MOLD
Starting with the center station, position the station so the centerlines match the mold and strong back, and check that the centerline is perpendicular to the base with a square. Best to position the station with a couple of clamps, then use screws to hold it. Mount the second station, fasten a baton or cedar strip temporarily to the top of the first station, with a small nail or screw, and continue with the rest of the stations. Check each station with a square or level to be sure it is vertical before tacking to the top baton. Mount the stem mold and fasten it to the end station, ensuring they are both vertical and square. When you have finished mounting the stations the baton should describe a fair curve just touching the high side of each, this can be removed after a few strips have been added.
FAIRING THE MOLD
Place a cedar strip about a foot longer than your outstretched arms on the mold parallel to the base holding it near the ends, it should make a fair curve and just touch the high edge of each station. Move the baton around to check the whole mold. Minor high spots can be sanded down, but any major discrepancies mean a station is either incorrectly cut or out of position. High or low spots over 1/8” will probably show in the finished canoe.
BENDING AND GLUING THE STEMS
Make a steam box with a 4” plastic pipe, and set it on the end over the spout of a kettle. Put one set of inner and outer stems in the pipe, and close the top with a rag. Steam for at least 1 hour, a second kettle on standby helps in case the first runs dry. Pull the strips, stack, bend, and clamp over the stem station. The wood will dry quickly when removed from the steam box, so have clamps ready and move fast. Leave clamped until dry, several hours, repeat for the other stem.
Cover the stem mold with packing tape or plastic to prevent sticking. Glue up the 3 inner stems, cover them with packing tape, and glue up the outer stems. Dense oily woods like ash do not glue well with epoxy, so sand the glue surfaces with 40-grit paper to rough it up. Brush a thin layer of mixed epoxy on the gluing surfaces, set aside for 3 or 4 hours until it gets tacky, mix another batch thickened with cabosil, and clamp in position. Do not over-tighten the clamps as this will just squeeze out the adhesive. Have some small clamps ready to align the edges as the strips will slide around on wet epoxy.
Strip color can vary from light to pink to dark. If you have space lay the strips out on the floor and arrange them by color before you start planking. Cover the mold station’s edges where the strips will be attached with packing tape or with poly plastic, this prevents the strips from sticking to the mold when glued and glassed. If you are using an Arrow staple gun to fasten the strips use ½” staples, tape a piece of cardboard or plastic about 3/32” thick to the bottom of the gun just behind the staple. This will prevent the crown from marking the wood and remove it easily with wire cutter pliers or a staple puller. There are various methods for shapeless construction you can find on YouTube.
Place the first strip cove side up against the bottom edge of the center mold, and fasten with one staple. Allow the strip to take a natural curve to the ends, be sure both ends are an equal distance from the base, and hold this strip temporarily with pieces of tape until it is positioned. Do not try to bend the strip to match the sheer line as you will not be able to continue this bend after the first few strips. Fill the ends with short strips later. Run a small bead of Titebond 3 wood glue into the 1st strip cove and fasten the next strip, wipe off excess glue with a damp rag. When you get to the bottom football use a fine tooth saw and small plane to trim and fit strips.
Joining strips is easy, all Noah’s strips are shipped with square cut ends so just butt 2 strips together with the Titebond glue supplied and add the next strip on top to lock it in place, you don’t need to join the strips before putting them on the mold. If you are careful about matching the colour of the wood at the joint it will not be very visible after fiberglass and varnish. The wood, and it doesn’t matter what kind of wood, is just a mold for the fiberglass, the fiberglass skins hold everything together and keep the canoe shape so no need for scarfed joints.
FAIRING THE HULL
Trim the strips square with the inner stems, glue on, and round off the outer stems. Pull all the staples. Use a spokeshave or small block plane to level high spots on the planking. Low spots can be shimmed from the inside. Use a fairing board or ½ sheet sander with 80 grit paper to sand the hull until fair. Do not even think about using a belt sander. Do not use a small finishing sander at this time either as it will follow low spots that will show when varnished. You can make a fairing board out of a 4” or 6” 80 grit sanding belt glued to a piece of ¼” plywood, glue handles to the ends, and the board should be able to flex slightly. Move the board mostly at about a 30-degree angle to the base until the hull is smooth with no high spots. Do not over-sand as you should have at least 3/16 of cedar before glassing.
Vacuum the dust off the hull. You will probably see some small gaps in places between strips, these will need to be filled. Mix a 2 or 3 oz. of epoxy, stir in sanding dust or wood flower with about 25% cabosil until you get peanut butter. Use a flexible plastic spreader or ¾” putty knife to fill the gaps, do not overfill, scrape off all excess. It helps if you cut the spreader about ¾” wide so you don’t get goop all over the canoe. Don’t bother filling staples and pinholes, they will fill when you do the fiberglass. A 6” random orbit sander with a soft pad works best, but a finishing sander with 120 or 180-grit paper will also work. Sand the hull smooth, check with a baton, and run your hand over the hull to make sure there are no more bumps or dips.
Stain can be used to even out, change wood colour or cover mistakes. Mohawk Ultra Stain is an alcohol-based wood stain that is available in a variety of colours and works well under Epoxy. Do not use oil-based stains with Epoxy.
Fill, fair, and sand the hull to 120 grit, remove dust with a vacuum and tack cloth. Do not wipe down with any liquid. Wet a balled-up clean cotton cloth with the stain. Rub vertically and then horizontally starting at one end, and rewet the cloth as necessary. Try to avoid overlapping as much as possible. When dry the surface will appear blotchy. This can be evened out by rubbing with a 3M Blending pad. A second coat will make the stain more even, but will also darken it. Most variations in colour will disappear when Epoxy is applied. Remove dust and apply a sealer coat of Epoxy. Do not get any water on the stain before the Epoxy as the stain will run.
FIBERGLASSING ~ This ain’t rocket science!
The ideal working temperature is 20C/70F. Higher temperatures will reduce the pot life and working time, and lower will extend pot life but the resin will thicken so will be more difficult to spread. If you must work at lower temperatures keep the epoxy cans in the house at room temperature and bring them out when glassing. Do not heat the epoxy, this will shorten pot life and make it very hard to predict working time. Try to avoid fiberglassing below 10C/50F and above 30C/90F.
If you want to apply a sealer coat of epoxy just roll a thin coat with a 4” low pile foam roller, allow it to dry, and sand with 80 grit before fibreglassing. This step is not necessary as long as you follow the instructions below, but if you like sanding go for it. Do not put fiberglass over wet or tacky resin as you will not be able to move the glass around to remove wrinkles.
Vacuum the hull or wipe with a clean dry cloth to remove dust, do not wipe down with any kind of solvent. This works better with 2 people but, can be done alone. Unroll the glass down the center of the canoe so it drapes evenly on both sides and at least 3” beyond both ends of the canoe. Use your hands, to gently smooth the cloth from the center to the ends, do not pull as it may separate the weave and show in the finish. There will be some pleats down the sides, these will be worked out as the resin is applied.
It is best to start in the morning as you will want to apply 3 coats of epoxy, one to wet out the fiberglass and 2 more to cover the weave. If you only do one coat you will have to sand the next day and the glass weave may show when you recoat. You can use pumps to measure the epoxy but graduated mixing pots (MM1Q) are faster and more accurate. Just set the pot on a flat surface at eye level, pick the ratio 2:1 or 5:1, pour the resin into a number (say3) on the left side of the line, and pour the hardener on top to the same number (3) on the right side. Mix thoroughly for 1 minute scraping the sides and bottom. Depending on temperature and hardener you will have 10 to 20 minutes of pot life, this can be extended by pouring the mixed epoxy into a paint tray. If you have a helper appoint them the designated mixer so you have freshly mixed epoxy when you need it. Start out with about 12 oz. and mix more as needed, adjust quantities as you go. If the mixed epoxy starts to gel or becomes warm, chuck it, do not continue using epoxy that’s starting to kick off.
Start in the middle of the canoe, and work to one end. Pour a bead of epoxy about 4’ down the centerline. Use the flexible plastic squeegee to spread the epoxy and your gloved hand to hold the dry glass from sliding around. Use enough pressure on the squeegee to move the epoxy so there are no wet spots, but not enough to drag epoxy out of the weave and cause dry spots. If you can see white fiberglass, it is too dry. Add more resin and spread with the squeegee again if necessary. After the flat bottom has been wet out you will need to add resin to the sides with a 2” brush or low pile solvent-resistant foam roller. Don’t use cheap rollers or you will be (trying to) pick bits of foam out of the wet resin. Use the squeegee to even out the resin and smooth the cloth, continue to the end using your hand to smooth out the dry cloth before wetting.
When you get to the end, trim the glass so you can wrap around the end by 1”, trim the other side and wrap over the opposite side. This gets a little fussy so don’t spend a lot of time on it, you will need to finish the other end before it starts to gel. The double layer of glass will also show slightly. An easier solution is to cut the glass just behind the stem, cut another piece on a bias (45/45) about 2” wide and the length of the stem, and lay over the stem. Wait until the first coat of epoxy starts to gel, (2 to 5 hr) roll on another coat of epoxy, and repeat once more. When the epoxy /glass gets rubbery you can the trim cloth overhang along the sheer with a razor knife.
Next day, sand with a 6” random orbit, or finish the sanding with 80 grit paper. Epoxy gets harder with age so best to do the initial sanding ASAP. At this point, you can continue sanding up to 320 grit, or leave it until you have finished trimming out, just before varnishing.
TURNING THE HULL
Remove the first 1 or 2 stations from the inside. You should be able to pull the hull off the mold at this point by pulling it up from the edges, wear gloves, cured fiberglass will cut your skin. The hull at this point will be floppy but will be rigid when the inside is fiber glassed. Support the canoe right side up so it does not rock, cut a stick the exact width of the center station at the sheer and 2 more from stations about 1/3 of the way from each end. Position the sticks at the sheer of the canoe corresponding with the station positions. Run a string line from end to end. Sight either side of the string to make sure everything is symmetrical, with no twists. This will be the final shape of the canoe. You can make a temporary cradle by trimming 1/2” from the inside of 2 station mold cut-outs, and line with duct tape to prevent scratching. Set up the 2 cradles on a base making sure they are level and straight.
FIBERGLASSING THE INSIDE
Use a rounded paint scraper or chisel to remove any glue or epoxy that has leaked through the seams, and sand smooth. A 6” random orbit sander with a soft foam pad or soft interface pad works best. A finishing sander will also work but will take longer. A hard-edge sander will leave marks on the cedar. Hand sand the ends. Make up a mixture of wood flower and cabosil, put a ¾” fillet in the ends, fill any gaps in the planking, and sand smooth when dry. Sand the sheer and round the edges slightly so dry fiberglass has no place to snag. Again this is easier to do with help. Normally only one coat of epoxy is used inside so as to leave a nonskid surface. Do not sand when hard, just scrub with clean water and a Scotchbrite pad before the varnish is applied.
Fold the glass lengthwise and lay in the bottom of the canoe, and spread it carefully towards the sides and ends. Place 4 or 5 (zip lock) small sandbags along the centerline to temporarily prevent the glass from sliding around. Spread the glass up the sides and over the sheer, and hold it in place with spring clamps or clothes pins. Do not use tape as it will disturb the weave when you try to remove it. The glass should be slightly loose making sure there is enough where the bottom turns up into the sides. Remove sandbags.
Mix about 12 oz of epoxy; pour a bead down the center, being careful not to disturb the cloth, and spread with a squeegee toward the sides smoothing wrinkles as you go. Mix another batch, and pour into a paint tray, starting in the center use short foam rollers to spread epoxy from the bottom up the sides, smoothing wrinkles as you go. It works better if you roll at a 45-degree angle. Be careful not to lift the glass off at the turn of the bilge. Remove the spring clamps when you get to the top.
When you get to the ends, cut the remaining dry cloth down the middle, fold back one half, and work the other half around the fillet, a dry brush helps. Trim so it overlaps about 1” onto the other side. Repeat with the other half. Roll resin as far as you can, finish with a brush, and tape to a stick if necessary. Repeat with the other side so you have a double overlap. Go back to the center and finish the other end. Use the spacers at the sheer to check beam spacing before the glass cures. If you have to leave them in to maintain the right shape, put some wax paper or packing tape around the ends to prevent sticking to the epoxy.
GUNWALES, DECKS, SEATS
Gunwales can be either screwed or glued in place. Screwing allows you to remove the gunwales easily in case of damage, gluing means you will probably never need to change them. No weak spots caused by screw holes and no place for water to get in and cause rot.
Trim outwales to length so they meet just past the ends of the canoe. Glue and clamp so the outwale is slightly lower than the sheer strip, if you do not have enough clamps use screws from the inside. Use the spacers to check that the hull shape is correct before the glue sets. Remove screws and fill holes with epoxy before installing inwales. Mask the inside of the hull about ¼” under the gunwales to catch runs. Run your finger under the outwale to make a small fillet, remove excess glue, and remove tape when the epoxy starts to get tacky.
Trim the sheer strip so it is flush with the outwale. Dry fit the inwhale to length tapering the ends to fit, glue or screw flush with outwale. Trim decks to fit, and glue them in. Dry fit seats, yoke, and thwart to be installed after varnish
Epoxy will chalk and discolour after exposure to the sun. You will need at least 3 coats of good UV filter Marine Spar Varnish if the canoe is stored out of the sun, 5 or 6 is best. Sand to 220 or 320 grit, vacuum dust, wipe down with a clean cotton cloth and water and allow to dry.
Dust is the enemy of a good varnish job. If you can, wet down the floor with water about 4 hours before varnishing, and or move the canoe away from where you were sanding. Wear a new paper suit or clean clothes, and wipe down with a tack cloth just before varnishing.
Apply varnish with a good brush in thin coats, cross-brushing as you go. Use up to 5% thinner to help flow, do not over-thin the first coats. Most varnishes are 1 coat a day, and sand with 220/320 between coats. Epifanes Woodfinish Gloss will allow one coat a day without sanding so you can skip 2 or 3 sanding’s. Bristol Finish Amber is a UV 2-part polyurethane clear that can be applied wet on wet so 2 or 3 coats a day without sanding, also much harder than conventional varnish.
Have fun and please send Noah’s pictures of your masterpiece.