Shortening a form

[samb]

I am deciding whether I should buy a 16 foot canoe form; It's not that I want a 16 foot form, I'd much rather have a 14 foot one but forms are very few and far between here in the UK.
I know it's possible to have one form and build different lengths of canoe, so how do I go about converting a 16 foot form into a 16 - 14 foot form? is it just a matter of cutting a section out of the middle and rejoining it? How do you make sure it's all in line and not twisted. I have some ideas but it's always useful to listen to others.
Pictures would be very useful if possible

Thanks
Sam

 

[Dave Wermuth]

NO photos, but I did that. I took 42" out of the middle of an 18' canoe form that I built several years ago. I've modified the form a couple times. I have a reasonably serviceable solo 14.5' form. It's not easy to do. The shape of the middle is important and it gets removed. The width changes. It's not that tough to align the two parts but the wood strips have to be re-woven together. And the thing has to be faired.. I suppose you could disassemble the whole thing and set the forms together closer. and then put it all back together. Mine worked out but I knew it could be a big flop. I've flattened the mid section as it was too rounded to suit me. My journey started with an 18' Penn Yan guide basket case. I built the form based on it. And then I shortened the basket case canoe. It turned out ok so I decided to try to shorten the form. This was over the course of several years.

 

[Todd F]

My first inclination was to post a picture of a chainsaw but you guys are all over this...

 

[samb]

So it might be a challenge then.........

 

[Andre Cloutier]

Its not so much a challenge concerning the work, but you wont really know how the new hull will behave. From my understanding factories would stretch a build on the same form, like building a 17' on a 16 form etc, however that didnt do much to alter the lines and perfomance of the boat by elongating the ends. Your ends will remain the same but the new profile of mid section will be an unknown. if you batten off the two haves and fair it well, i'd say you have a fighting chance of a workable outcome. Restoring a 14' right now, and it will literally fit in side a 16'er. so you wont be able to reduce the overall volumes accordingly, which would be my concern

 

[chris pearson]

Its not so much a challenge concerning the work, but you wont really know how the new hull will behave. From my understanding factories would stretch a build on the same form, like building a 17' on a 16 form etc, however that didnt do much to alter the lines and perfomance of the boat by elongating the ends. Your ends will remain the same but the new profile of mid section will be an unknown. if you batten off the two haves and fair it well, i'd say you have a fighting chance of a workable outcome. Restoring a 14' right now, and it will literally fit in side a 16'er. so you wont be able to reduce the overall volumes accordingly, which would be my concern

As much as I’d like to disagree with Andre, Hes spot on…

 

[Dave Wermuth]

I was able to insert a random photo or two of the canoe. It's awaiting canvas. Like Andre says, the final outcome is a gamble. I'll look for another one that is done.

 

[Dave Wermuth]

Here are two more photos. the first one with the good looking paddler is the original PY Guide that I shortened. The second one that is upside down is one of the first I built from the shortened form.

 

[Dave Wermuth]

Oh, and one other thing. The depth. It will be proportioned to the longer canoe. I did not make the form shallower. What you see is the depth of the original 18' PY Guide.

 

[samb]

Thanks for this Dave, Andre and Chris. It seems it's much as I was thinking . . . . except I never thought about depth!

Sam

 

[Dan Miller]

If you go back in time before canvas canoes were the norm, the lapstrake builders, like Rushton, would build several different lengths of canoes on the same set of molds. Of course that was easier because there wasn't a solid mold.

I also recall that Douglas Ingram (Red River Canoe and Paddle in Winnipeg) build a mold with a removable section. You could try contacting him about the effort it took. Some of the old war canoe molds also had removable sections to change the length, but that would be easy given that the center sections were probably fairly straight over their length.

 

[samb]

Thanks Dan. I like the idea of the removable section but as you say, it might cause fairing problems