Do-it-yourself foam bulkheads

Just got a used Seascape II tandem kayak ( It comes with two bulkheads–one fore, one aft–but nothing in between. Nice for carrying things, but a nightmare if I should capsize, with all that water to get out. I was thinking of installing a bulkhead (or two) to cut down on volume. Probably out of foam to keep them light. Any idea of how to go about this? Many thanks in advance.

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Bulkheads would be difficult. What
about an air bag? If, as appears, your kayak is “glass,” you can install tie points on the top, sides, and bottom to hold a bag in place. There are some very light and durable bags available. There is a chance you might find one that incorporates storage as well as floatation.

You’ll need a hatch, too
If you’re going to wall off a section of the boat between the cockpits, you’ll need to install a hatch to allow you to access it. If you don’t want to tackle a deck mounted hatch, consider installing rigid bulkheads with a hatch mounted in one of them. It’s pretty easy to make flat fiberglass panels for jobs like this.

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the problem is the math
How do you figure out the pattern? I suppose there’s always guess work, and there must be a formula (I should have paid more attention in geometry!), but how do you ensure you’re getting the pattern right? Practice first with cardboard cut outs? Closed cell foam is too expensive to get wrong.

Do I really need a hatch? A drinking straw to equalize teh air pressure should be enough. The lost volume doesn’t mean that much to me. On the other hand, maybe I should just invest in two sea socks and forget about it.

I have a three hold Grand San Juan from Eddyline and I added a batt op. pond pump. works great.

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wire template for bulkhead . . .

– Last Updated: Mar-12-10 10:13 PM EST –

Find the exact location(s) where you want your bulkhead(s). Tape (electrical tape) around the circumference at that location, perpendicular (vertical) to the longitudinal axis of the kayak.

When you are done taping, you will have an outside representation of where the edges of the bulkhead will be inside the boat. Take heavy gauge wire and, keeping it inline with the same edge of the tape, bend the wire around the entire circumference of the boat, cutting the wire and taping overlapping wire ends together where they meet.

When you slide the wire outline off the end of the boat, you will have the outline of your bulkhead, plus the thickness of the hull material. Usually, this will not be a problem to just go with the thickness you have, especially if you use the tape edge guideline facing the narrow end of the boat.

Now, you can just use the wire for your template, but it is subject to bending with manipulation, so it's best to lay the wire template/outline down on some heavy cardboard and trace the outline around the INSIDE of the wire template.

Cut out the template from the cardboard and try it for fit inside your kayak. Are there edges that are outside the hull perimeter? Trim them. Are there "scallops" where the template doesn't meet the kayak hull? Add tape to bring the line to fit. Make sure the bulkhead fits where you want the bulkhead.

Now, you can use the cardboard bulkhead template as a pattern to cut out your bulkhead from the desired material.


Quick ideas …
Bend wire outside the hull to fit, then transfer.

Trace with pencil taped to small triangle thing with only two small points contacting the hull …Repeat 'till you get from seam to seam.

Tape over hull … use anything from paper mache to glass epoxy to lay over, let harden … pull sand one side to get perfect.

All / any above … Transfer to cardboard template with two ‘bowling ball’ holes cut in the middle so you can handle it easier … fine tune as ness. with a pencil and scissors before tracing on your foam.

DO NOT cut foam too big and jam it in … the thickness of the pencil you trace it with is almost too much … Beware cutting it @ an angle too with your sabre saw.

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Wire contour guide…
…I use the softest solder wire I can find.

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trace a bulkhead on cardboard
I was looking at some pictures of people making stitch and glue boats, and to make a bulkhead they cut out a piece of cardboard roughly the shape of the kayak, then drilled a hole in the center of a top of an advil bottle, put a pencil lead in the hole and traced around the inside of the boat. This gave them around an inch offset from the boat to the rough cardboard cutout, making the cutout slightly smaller than the actual bulkhead size. They then cut out that traced line and did the reverse, tracing around the cutout to make it around 1 inch bigger, which is the actual size of the inside of the boat.

The inside approach might work well if
the person doing the work is 25 years old or less and 3 feet tall. Trying to reach inside the hull to work on many kayaks - especially set up a bulkhead placement - requires impossible contortion skills and coordination.

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If you’re installing two bulkheads…
…yes, you absolutely do need a hatch to allow accumulated moisture in the compartment to dry. Even if you never capsize the boat, moisture will accumulate due to condensation. It also doesn’t make any sense to simply throw away usable storage space.

As others have pointed out, there are many ways to create a template. If you use fiberglass, you don’t need a close fit, as you will be glassing it in with tape that seals any gaps around the edges. With Minicel foam, you need to cut the bulkhead slightly oversize so you get a tight friction fit, even though you will be sealing it in place.


Lots of nice response last Septmeber
I posted much the same question and got lots of good help here last Sept. Too bad the archive or search is so thin here, there was a lot of good info.

Here’s my project:

Make a rough guess template and stick it inside the hull where you want the bulkhead. The use little strips of 3x5 cards and tape them to your rough template so that the edge of the card is flush against the hull. Do that all around and you can get a pretty good idea of what your second draft template should look like.

I tried using wire on the outside of the boat and it worked poorly for me. Your mileage may vary.

Somebody posted a way to make a depth gauge such as carpenters use to duplicate a pattern, only theirs was kayak-sized. Very cool, but I can’t remember the details and didn’t want to go to that length.

You definately want a hatch. Chance of water getting in there at some point, somehow, is pretty close to 100%

Good luck with it.


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If you are just trying to fill up the space. Make a Float bag (inflatable). It’s what we use in kayaks.

Seattle Fabrics makes a heat seal fabric that seals with a home iron. This is the stuff used to make air mattresses.

Buy the lightest weight fabric (they make 3 weights).

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silver wire
Wrap silver wire around the hull where you want the bulkhead. Twist it snuggly, and gently slide it off one direction or the other. Trace the inside of the wire on to foam, or a glass panel. Cut said panel and install in boat with either contact cement and Lexel, or glass tape and resin if a composite panel.

Install hatch in bulkhead or deck. Easy as can be. Done it many times in R&D on proto’s.

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thanks chip
I like it. Thanks to everyone for their responses. Gives you something to think about. Helpful stuff all the way around.

Seems to me, you need “or two”.
Don’t you definitely need 2 bulkheads to actually decrease the space that water could get into?

If you have 1 bulkhead fore and 1 aft, I assume the rest of the boat is wide open (ala, stick your head in one cockpit and can see through to the other). In which case, adding just 1 bulkhead would only separate the space, not decrease it at all.

count that a rhetorical flourish

I don’t even see the room
With leg room for the aft paddler, how much room is there? It looks like leg room will be encroaching to within less than a foot or so of the fore paddler. Could be the pictures, but this doesn’t look like a stretched tandem with a third hatch (possibility). Even if it were, a bag is the solution unless you need the storage between paddlers.

the picture is the best I could do
The best I could find on line. Mine’s actually a Seascape 2. The one in the picture is a point five, a shorter boat. One of the advertised selling points of the bigger boat is its volume for oversized stuff. I suppose I’m a wuss, but I plans to use it with the kids; would like to bring its seaworthiness up a notch, just in case.

You’re adding two gray things?
I know someone who would be very proud of you.

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