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Replacing bulkheads in plastic kayak

Posted: Mon Jun 07, 2021 4:22 pm
by samej
Hello,

I have a North Shore Atlantic RM and the bulkheads leak slightly. I was going to just put some fresh Sikaflex in there but noticed they are about 6 inches thick each. With three bulkheads this loses quite a bit of volume in the boat that could otherwise be used for kit. Is it possible to replace them with something thinner, could I make something out of plywood for example? I imagine in a plastic boat the difficulty would be securely fixing them in place?

Thanks
James

Re: Replacing bulkheads in plastic kayak

Posted: Mon Jun 07, 2021 11:21 pm
by ChrisJK
I have an old Capella and found a bulkhead leaked slightly so I used an appropriate bathroom sealant or similar and it has generally worked.

Re: Replacing bulkheads in plastic kayak

Posted: Tue Jun 08, 2021 2:40 am
by Jim
Replacing foam bulkheads with solid ones will cause hard spots which will cause excessive wear to your hull in those areas and you may find in time that the PE flexes away either side leaving hard ridges where the bulkheads are. This might not bother you if it is already fairly worn out, plus whilst it might look a bit crappy, I can't say for sure it will actually shorten the life of the boat.

But 6" foam sounds excessive, I would have thought 2" would have been watertight enough, 4" max. Most kayak shops sell 4" thick closed cell PE foam for outfitting, if there is a choice go for the higher density version (30kg/m^3 if I recall). Just stick them in with a bead of sikaflex around the edge, and then fillet it neatly after if you want.

Re: Replacing bulkheads in plastic kayak

Posted: Tue Jun 08, 2021 7:54 am
by Dyllon
I suspect that the manufacturer has used 6 inch foam to add support to the hull at the approximate location of the common tie down points. The foam is compliant and prevents the issues described by Jim above but the 6 inch width provides sufficient structural support over an area of the hull despite the low stiffness of the foam.

If you take care tying the boat down, it may not matter :-).

Re: Replacing bulkheads in plastic kayak

Posted: Tue Jun 08, 2021 9:33 am
by samej
Thanks all. I might have a look into getting some slightly thinner foam.

I can't actually get my roofbars to align with the bulkheads unless the kayak is sticking a long way out at the back, so I'm pretty carefull with the straps, and am looking to get some j bars to help.

Re: Replacing bulkheads in plastic kayak

Posted: Wed Jun 09, 2021 12:26 am
by charleston14
If you always need extra load space volume it may be time to change kayak ?

Re: Replacing bulkheads in plastic kayak

Posted: Wed Jun 09, 2021 10:53 am
by samej
That is an option! I'm hoping to do a multiday trip in it soon so will have to see if I can squeeze everything in there.