How many layers of fibreglass for bulkheads

Submitted by Shawn on Sun, 05/03/2020 - 14:35

How many layers of glass cloth should I use for bulkheads?

i can add extra support for my feet where needed.

My first two kayaks were build back in 1983. None of the kayaks I've built and paddled for 4 decades has ever had fibreglass on the bulkheads. They have never had any breaks or stressing either.

Support for feet is full foot pedals for steering. There is only one very easy to access adjustment needed for positioning. We were paddling kayaks in Samoa earlier this year with 4 difficult to get at adjustments needed and uncomfortable foot supports too.

If you have some thin plywood its much easier, just coat with epoxy for water-proofing

I have only made seats out of glass, I usually use 6 layers of 6 ounce cloth, to I would think at least 3 layers for a bulkhead

JohnAbercrombie

Mon, 05/04/2020 - 12:12

For keeping water out, a bulkhead can be quite thin.  I've found that something a bit thicker than the minimum is easier to handle when installing and  provides a more confidence-inspiring footrest. For curved bulkheads (behind the seat) you can use a thin sheet and glass over once it is installed.

You should do a quick experiment with scraps, if possible. The aramid (Kevlar?) will be thicker and soak up more epoxy than glass, so 3 layers might be enough (glass-aramid-glass).  With straight glass I'd probably use 4 layers. A bulkhead (where I value stiffness) is probably not the optimum place for Kevlar, but if you have a scrap piece, go ahead and use it.

It also depends on how you are doing the layup. With a mylar sheet underneath and peelply on top, I get a strong layup with one glossy surface.

 

Sand both sides for an inch or so around the edges before you fillet.

 

With a good fillet, it's quite difficult to push the bulkhead into the narrower part of the boat with your feet, so I wouldn't worry about reinforcement, much.

Angle the bulkhead if you are using for a footrest. Experiment to find the angle - probably 65-75 degrees or so..

Don't forget to put a breather hole in the middle of bulkheads.