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PostPosted: May 14th, 2013, 12:02 am 
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Has anyone cut out the flotation tanks on a kevlar canoe so another one can nest inside? I know clipper will build theirs without tanks for this purpose and I think it would be easy to outfit the boat with a small airbag laced in to make up for the flotation that was lost when not tripping. The flotation tanks appear to take about 16 inches on each end. The boats I am considering nesting (helman scout and hellman prospector) are 21 inches different in size so I think I could remove just one tank and they would nest fine.

Then I'd have to deal with the seats and thwarts but that should be easy

I wonder if the hull would be noticeably less stiff due to loss of the stiffening?

Any ideas appreciated in advance.

Kevin


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PostPosted: May 14th, 2013, 1:38 am 
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Location: Burns Lake, BC
I would guess that the Hellmans would be much more flexible (without air chambers) than Clippers.
The Clipper layup is already that much more than a Hellman layup judging by the heavier weights common to any Clipper. Different materials aside.

How about a plug of shaped mini cell strapped in? I bet that would be just as sound as a glassed chamber. Easier to deal with than a bladder.

Yes, the seats and thwarts are very easy to deal with.


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PostPosted: May 14th, 2013, 7:41 am 
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You might not notice much change in stiffness, but it might make a difference if you run bow into a rock. The maker should have calculated layup based partly on the cross-bracing effect of the air chamber.

You won't gain much space by removing the chambers, and you might not find a float bag to neatly fit each space. I'm not sure that minicell strapped in would have anything like the same bracing effect.


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PostPosted: May 14th, 2013, 7:19 pm 
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Bob hellman gave me the following reply.

"We have nested the Scout inside the prospector but you do have to take out the float tanks. This does not affect the structure of the boat. You should glue in some close cell foam under the gunwales inside for floatation.
Thanks
Bob"

So I think I'll follow teds suggestion and use a chunk of closed cell foam in each end to replace the tanks. I can glue in a few rings to tie them in and just make them semi permanent.

Thanks for the advice. Now I just have to align my schedule with teds to pick up my new used prospector!


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PostPosted: May 15th, 2013, 9:19 pm 
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Location: Lower Saranac Lake, NY
It is amazing someone would compromise the structure of a boat for such obscure reason. Of course, warranty will void, the longer distance without support will oil can more, all in all a really poor idea unless the stacking is critically important.


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PostPosted: May 16th, 2013, 7:30 am 
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Charlie, Nesting canoes is really important on fly-in trips. Beacuse there are limitations on how many canoes can be strapped onto the floats of floatplanes. It's expensive to make extra trips to get canoes in or out. So people pull the thwarts and nest canoes inside other canoes. It's a common discussion here on CCR about what canoes fit into what other canoes. So while it might be obscure to most canoeists, it's really not an obscure reason for many on CCR.

PK


Last edited by pknoerr on May 16th, 2013, 1:34 pm, edited 1 time in total.

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PostPosted: May 16th, 2013, 11:26 am 
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The manuf has said that it won't affect the structural integrity.

_________________

Old canoeists never die---they just smell that way.



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PostPosted: May 16th, 2013, 4:33 pm 
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wotrock, the manufacturer is not the final arbiter of truth. And what they say does not mean anything unless they define what they mean by "structural integrity".


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PostPosted: May 16th, 2013, 7:39 pm 
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I don't think I would consider cutting them out if there was a significant risk it would compromise the integrity. I want to stack canoes because we plan on several trips where if we can't stack we would need to pay for two plane trips and that will really add up. I could buy a royalex boat and not worry about air tanks but I want a kevlar boat because we also portage on some trips and I want the speed of a kevlar for some flat water trips.

So I think I'm going to go for it. There is a fellow in town who used to work for hellman and does really nice canoe repairs so I can get a good job of taking out the tanks. If it doesn't perform as well as I hope, then I would have an option to put back smaller tanks because the two boats are quite a bit different in length.

I appreciate the feedback. Ill report back on the finished product

Kevin.


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PostPosted: May 16th, 2013, 9:27 pm 
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If there is concern about loss of strength, you could smooth the area where the tank boundary has been scraped off, and put down a couple of concentric bands of Kevlar over the zone. And you could add a short thwart above.


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PostPosted: May 31st, 2013, 1:24 pm 
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Kevin, Dylan built both of his boats without flotation chambers (Scout and Cruiser). Not sure if he changed the layup to compensate for any structural factors, but he would be the guy to do the modification.

I've thought of the same for my boats to buy some more storage space. I always have flotation or gear lashed in anyway.

AT


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PostPosted: June 13th, 2013, 11:25 pm 
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Image

So I had Dylan cut out one tank and it was just a little short. So then he cut out the second. I removed one end plate and the boats fit nicely. I left the seat hangers in the Prospector which is why the Scout sits a little proud at the gunnels but I think its fine for flying.

Dylan worked at Hellman and is confident there won't be any structural problems.

I found a couple cheap kayak air bags at aquabatics ($10 each) so will just put airbags in for flotation.

Next week we head south with three canoes on board my truck!!

Thanks for the ideas. I'm happy with the product.


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PostPosted: June 13th, 2013, 11:36 pm 
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Location: Burns Lake, BC
Neat to see.
Careful about the seat supports rubbing the Scout's hull during nested transport.


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