May 22, 2011

Canoe Mold Build – Day 3, 4

Days 3 and 4 of canoe building have resulted in most of the mold being complete, or should I say we can at least “see” the canoe. All in all I would say that the foaming of the mold is taking much longer than I though. Kevin, Amy (yes she joined in too), and I have almost 30 hours into the foaming of the strongback and stations. Based off the book it seemed like in 4 hours Kevin and I would be able to square away the foaming, but I was wrong. We encountered many challenges along the way.

Bow/Stern Installation and Truing

Strongback alignment

Strongback alignment

We left on on day 2 with the stations attached to the strongback and the bow and stern built but not attached to the strongback. Attaching the bow and stern is straightforward as they both have vertical and horizontal square marks which you line up with the T shape of the strongback. The bow and stern attach to the front and end of the strongback, they do not go on the top of the strongback like the stations. Attaching the bow and stern is as simple as aligning the marks and attaching with a few screws.

Next we stepped into the alignment of the stations and bow/stern. The goal here is to ensure that all of the stations and the bow/stern are aligned to help create a straight uniform canoe mold. Failure to do so can result in a crooked canoe, which is not going to make a very good sea going vessel. To ensure alignement we attache a string from the stern to the bow. Next we look at the square marks that are on top of the stations (we put these marks there when we transfered the drafting templates to the plywood) and ensure they line up with our string. If they do not align, then we unscrew the station from the strongback and shim it until it lines up. We go up and down the strongback doing this as needed to each station. We also want to ensure that the bow and stern are both vertically plumb. In all honesty I am not sure that Kevin and I did and I have reason to believe our bow may be “off”. More to come on that later as Kevin and I uncover the issue.

Once all of the stations are aligned with the bow/stern on the stongback, and the bow/stern are plumb we tack a small strip of wood (.75″x.25″x16.5′) from bow to stern to ensure the top of the stations do not move as we start applying the foam. This strip of wood will be removed once we get towards the top of the stations with the foam. Kevin and I tacked the strip in using a brad nailer which worked great. Moran suggested using small nails which would work also, but if you have access to a brad nailer it really speeds up the process and reduce the likelihood of moving the stations out of alignment when hamming the nails in.


The foaming process seems simple on the surface, but comes with many little gotchas that can be avoided with a little forewarning. Cutting the foam is simple work for a circular saw with an adjustable fence and a few 2″x4″s. While simple, cutting the needed 3-4’x8′ sheets of foam does take about an hour. The goal is to cut 1 5/8″ strips of foam in a trapezoid shape. This shape allows us to lay the foam over the curves of the stations and allow space for the glue to squeeze out.

Foam Cutting

To cut the foam set the blade depth to penetrate about a 1/16″ below the depth of the foam and set an angle of 8*. Lay a couple 2″x4″s on the ground. You will set the foam on the 2″x4″s to cut and give the foam strength as you gentle walk down the foam while cutting. To get the trapezoid shape you will make a cut going direction “A”, and then you will flip the sheet of foam over on the 4′ edge and make a cut in the oposite direction (B) on the opposite edge. As you repeat this operation of flipping the foam and changing the direction you are cutting from your will create strips that are a trapezoid in shape. You will need about 2.5 sheets of foam cuttup for a 16.5′ version of the James Moran’s Tripper canoe.

Foam Installation

Foaming up the strongback

Foaming up the strongback

The installation of the foam is where the foaming process “got out of hand” time wise. Glueing 1 5/8″x1″ strips of foam accross a frame of .5″ plywood is not as fast at one would think. As this is coming from a former custom cabinet maker who is being assisted by a fellow current custom cabinet maker and licensed contractor (Kevin). So technical skills sets with the tools and materials was not exactly the challenge. Our challenges fell into a few categories: tools, twists, not enough hands.

On day three we had a single generic Tool Shor (a Menards discount brand) glue gun. This glue gun had three forms of operation (it was a single setting unit): not hot enough to melt the glue, too hot of glue which melted the foam, and the right temperature of glue. This right temperature of glue was like a rare mythical beast like the Loc Ness monster. It was spotted so rarely that it’s existence was constantly in question. This left us playing a game of force the cold glue out and how much foam can we melt as we attach. Plus the hotter glue had us spending a lot of our time just holding the foam in place while we waited for the glue to set up. The takeaway here is to buy a two heat setting gun to give you some form of control in regards to the glue temperature.

Day 2 of foaming complete

Day 2 of foaming complete

Day four we greatly improved our foaming operation. Kevin picked up a second glue gun, and more importantly one with two heat modes. On day four we truely found our groove with foaming. Both armed with low quality glue guns we attacked the strongback/stations/bow/stern with foam and glue resulting in being about 90% complete with the foam operation. The most difficult part of the foaming process was dealing with the twisting of the foam from the first/last station to the bow/stern. Towards the top of the canoe the twist was light and not much of an issue. But as the foaming operation moved up the canoe (remember the canoe is upside down as we build it) towards the bottom of the canoe the twists became more harsh, and the hot glue was having issues hold the foam to the bow/stern. On these hard twists we ended up using large amounts of glue, held the pieces for a longer time to allow the glue to set, and at the most harsh twists we used pieces of foam that only spanned from the bow/stern to the previous station.The fact of the matter is this is very challenging and will require you to excersize patience as you learn how to make the foaming of the bow/stern happen.

All in all the canoe molding is looking pretty good. We are almost done with the foaming which will then lead us into the sanding of the foam to create the final *perfected* shape of the canoe.

Key Takeaways

  • Alignment of the stations/bow & stern is CRITICAL!
  • Ensure the bow/stern are plumb. This is also CRITITCAL!
  • Foaming is a long process. Be patient. Plan to spend 2o hours on this process.
  • Definately ask a friend, spouse, neighbor, or child to help applying the foam.
  • Either ensure you have a good glue gun or ensure you have two lower quality glue guns.
  • Remember to have fun, you are building your own canoe!



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