May 4, 2013

Canoe Building – Floatation

Bow Floatation Ready For S-Glass
This past week Kevin and I built the floatation chambers (for canoe #2, White Lightning). Floatation chambers increase the buoyancy of the canoe to ensure it will float even when completely water logged. The displacement of water alone will keep the canoe afloat with people and gear in it. However if you start taking on water or completely water log the canoe, you will not have enough buoyancy to stay afloat. This lack of buoyancy could get very dangerous on windy and rainy days. So to solve this problem we add more buoyancy to the canoe by creating air chambers at the bow and stern.


Inspired by Wenonah (a major Kevlar canoe manufacturer), we decided to build our flotations as a square step that fits into the bow/stern. This is contrary to how James Moran describes how to build the floatation in his book Building Your Kevlar Canoe: A Foolproof Method and Three Foolproof Designs. He describes building a tear-drop shaped piece of foam that fits in the top of the bow/stern and extends to the bottom of the canoe at roughly a 45* angle. When doing this method for the DragonFly (first canoe), it was incredible challenging to accurately shape the tear-drop and you lost more foot room for the person at the front of the canoe.


To build our “step” that forms a water-tight floatation compartment, all we need to do is cut a piece of foam that is our riser and one foam piece that is our run (horizontally). The process of cutting the foam was trial and error. We used a band saw to cut and then slowly cut the pieces to shape by take a little bit off at a time. We stuck the foam in the respective bow/stern end and used a wide (3/4″) felt tip marker to trace the shape of the canoe onto the foam. This allowed us to get closer to the correct shape with each cut.

Once we were at the size necessary, we made a back-cut at roughly 45* around the edge of the foam. The angle of this cut will face toward the inside of the chamber being created so you will not see it. The purpose is to allow for a tighter fit of the foam against the fiberglass/Kevlar from the outside of the chamber. Note that when the pieces of foam are in place they fit fairly tight. We basically wedge them into place.

From there a little bit of sanding to taste and you are ready to S-glass the floatation. OR you could take it a next step and build cup holders into them as Kevin decided to do. I will speak more to the cup holder in future posts.

Tracing the shape of the canoe onto the Riser foam.

Tracing Canoe Shape Onto Bow Floatation Foam

The shape of the canoe traced onto the Riser foam.

Stern Rise Foam With Shape Traced On It

Cutting the Riser foam on a band saw.

Cutting Rise And Run Foam On Band Saw

Test fitting the Riser foam and marking it again to trim it even closer to the shape of the canoe.

Stern Floatation Rise Foam In Process Of Being Cut To Shape

Tracing the shape of the canoe onto the Run foam. I am running the marker along the gunnel.

Tracing The Shape For The Run Onto The Foam

Almost completed bow floatation step.

Bow Floatation Almost Complete

The final bow floatation step completed and ready for S-Glass.

Bow Floatation Ready For S-Glass


Beyond the book Building Your Kevlar Canoe: A Foolproof Method and Three Foolproof Designs, another great Kevlar canoe building resource is


One response to “Canoe Building – Floatation”

  1. Amy says:

    What!?!?! Cup holders on White Lightning? This I have to see!!! Color me jealous…

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