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Bottom of cedar strip canoe lifting off the molds

Submitted by KYStreamMusic - Wed, 5/5/21 » 12:40 PM

I am building a Prospector Ranger 15, cedar strip canoe. After I finished stripping and removed all my clamps the center of the bottom on the middle 3-5 station molds has lifted off the molds about a 1/4" inch. Aesthetically it looks fine, but it now has slightly more rocker than the original design and the bottom is more rounded that it should be. I think there is a number of reason where I screwed up to make this happen, but my question is should I fiberglass it the way it is or should I try and pull the bottom down to be tight with the molds, as best as I can, before I fiberglass it? I’m worried about the tracking and stability of the finished product. Does anyone have any experience with this problem? Thanks in advance for any help.

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RE: Bottom of cedar strip canoe lifting off the molds

» Submitted by hspira - Wed, 5/5/21 » 1:35 PM

Hi KY,

while i have not built the particular boat you are describing, i have built a number of cedar strip kayaks and can confirm that its pretty common that you can get some shape drift after you pull the staples out.

i don't think, based on my experience and talking to designers that the 1/4" pop is going to have any "observable-by-you" effect on the boats handling or characteristics.

that said, there are a couple things you can do to minimize drift:

let the hull sit/relax with the staples in for a week or two. this kind of building creates a lot of tension as the wood tries to return to its original shape. the wood will relax over time and be less likely to want to spring back if you wait.
apply heat to the hull to relax the wood. you can use a heat gun to make wood take a tighter bend as the heat will relax the fibres. even if you did not need heat to make the wood bend, you can apply heat to reduce the tendency for the wood to want to bend back to its original shape. (sort of like the prior point but accelerated).
temorarly anchor it from the inside to hold it on the frame while you glass the outside. you can use a spot of hot glue to temporaily tack it in place. the hot glue can then be melted to release it.

i hope this was helpful.

RE: Bottom of cedar strip canoe lifting off the molds

» Submitted by KYStreamMusic - Thu, 5/6/21 » 1:15 PM

hspira

Awesome thanks for the advise. If I was to clamp it back down and set a heater underneath it on the strong back do you think that would be enough heat to make any diffrence?

RE: Bottom of cedar strip canoe lifting off the molds

» Submitted by - Thu, 5/6/21 » 2:21 PM

i don't think a space heater will get the job done.

i would go over the area with a heat gun that is getting the wood hot using the same technique that is used when you actually need to apply heat to get wood relaxed enough to take a bend it normally would not accept.

on my heat gun, this is going to be a setting around 200 degrees. i don't want to burn or toast the wood, but this is bringing it to a point that it is too hot to touch. you can practice on a scrap piece of cedar strip to see the effect i am talking about.

the link below has a good overview on using a heat to bend cedar strips:

https://laughingloon.com/shop.tips.html

RE: Bottom of cedar strip canoe lifting off the molds

» Submitted by hspira - Thu, 5/6/21 » 2:22 PM

see post above.