Hello Everyone, I've got some extra resin and cloth from a surfboard repair so I thought I'd finally try to fix the cracked polycarbonate bulkheads in my 17 year old kayak. I have what looks to be 8 oz cloth and some of that nasty choped up stuff that i think is called figerglass mat. I'm thinking the bulkhead should be about as thick as the hull maybe a little thinner. Does anyone out there know the layup schedule for a typical kayak hull or for a typical fiberglass bulkhead? Thanks, mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
mike dziobak wrote: > I'm thinking the bulkhead should be about as thick as the hull maybe a > little thinner. Does anyone out there know the layup schedule for a > typical kayak hull or for a typical fiberglass bulkhead? Lay out some wax paper on a flat surface, and then the mat with the 8 oz cloth on top. How thick is the mat? Should not be over an eighth of an inch. If it is over an eighth, just use two layers of cloth. Wet the layers out dry (e.g., use the minimum resin), avoiding wrinkles. Lay a thick piece of plywood covered in wax paper on top, and weight it with several concrete blocks. Don't really need the plywood on top, I suppose. BTW, 3 mm marine ply makes great bulkheads, glassed on one side with 6 oz cloth, but epoxy is better on wood. -- Dave Kruger Astoria, OR *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
mike dziobak wrote: > I'm thinking the bulkhead should be about as thick as the hull maybe a > little thinner. Does anyone out there know the layup schedule for a > typical kayak hull or for a typical fiberglass bulkhead? You can do pretty much whatever you want - just recognize that some bulkheads require more strength than others. If you are using the bulkhead in lieu of footpegs, the bulkhead should be stronger than if you are just using it as a waterproof wall between the cockpit and a dry compartment. If you are mounting a foot-operated pump on it, you would similarly need a stiff, strong bulkhead. Dave's advice is good. I'd suggest that two layers of 8 oz with nothing in between would be good if the bulkhead is in a low-stress environment. It would be reasonably strong but a tad flexible and possibly lighter than with the matt layer (less resin). 3mm okoume with one layer of 8 oz on each side would be almost bombproof. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Make the bulkhead laminate thinner than the hull and deck laminates unless they need to be structural (footbrace, pump support, etc.). That way if you run over something like a rock or a snag with the hull the (that causes the hull to flex as it slides over the object) bulkhead will give before the hull does when the rock or snag runs into the stress riser caused by the bulkhead. Because the hull is likely to be more flexible behind the seat than in front of your feet where it is narrower this is more important for the rear bulkhead. Do not use just two layers fiberglass cloth for the bulkhead. If you do you will likely have a problem with pin hole leaks where the cloth layers line up and little air bubbles can be hard to remove during lamination. In fact the bulkhead is likely to look more like a sieve if you use only cloth. It is far better to use one layer of fiberglass mat in the bulkhead as a sealing layer. So one layer of 8 ox. cloth and one layer of 3/4 oz mat would make a thin lightweight bulkhead. To beef it up some you could use another layer of 8 oz. cloth (to sandwich the mat between two layers of cloth) or use 1.5 oz mat for that layer in the two layer system. The more mat used the more brittle the bulkhead will be (on a pound for pound basis). Brittle or flexible is not necessarily a bad thing in a bulkhead as it is the part you would rather have break when faced with enough force to bend or break something on the boat. some have angled the bulkhead so it is not vertical for various reasons. This may also help it flex better and not be as much of a stress riser than if it was vertical. Matt Broze www.marinerkayaks.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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