fiberglass layup question

Ok - I have cut the seat out of my QCC 700X. I want to put in a new seat that is actually comfortably. What I would like to do is carve some kind of hard foam to fit the kayak and my butt, and then lay it over with a few layers of fiberglass, and then pad it. Problem is, every kind of foam I have tried is dissolved by the glass resin. I want the seat to have a back rest too. Don’t want to just make a seat out of minicell.

What kind of foam, or other substance should I use to make this work?

Why not just minicel?

If you use epoxy rather than vinylester
or polyester resin, you will have no problem with dissolving foam. The requisite amount of West epoxy and pumps will cost you maybe $65, but it will last in the cans for several years at least, while ester resins will set up into an unusable mess within a year or two.

Quality epoxy is the best buy in the long run.

Good question , because ester resins
don’t attack minicell.

and epoxy does stick
to all other resins: poly or vinyl, while the opposite is not so good.

Needless to say that epoxy also stinks so much less and is a superior product all together.

foamy butt
What follows is very imprecise remnants of a story I heard nth hand. I think LeeG might be able to provide some clarification if he happens by this post.

Apparently some kayaker used some expanding insulation foam, possibly in a trash bag, or maybe the foam was in a trash can and he sat over the trash can, to mold the shape of his butt. Then he cast the mold to make a form to lay up in FG, with the object of a seat custom shaped for his butt.

Real helpful, huh?


I remember it as…
Spray your butt with mold release then FG it…I think…

Just shape a minicell seat and glue it

You can add a hotseat pad if you want it to be a little softer.

Or…you can buy a ready made seat from Redfish (which is reputed to be very comfy) or perhaps the Bumfortable seat from PXT kayaks.

Bill H.

epoxy sounds good
I will give that a try, see what happens. I didn’t want to buy a premade seat, since I enjoy building and modifying.

Another ready-made seat

compatible foam

that’s pretty much it
1. line cockpit with plastic garbage bags.

2. Make one plastic garbage bag the mold for the bottom and two for the hips.

3. Since expanding foam won’t make an adequate mold if you’re sitting flat on your butt you have to do do successive pours(small!) holding yourself up off the bottom so the foam can fill in under and around your butt.

4. It’s an exact mold that is too tight so you should wear a LOT of clothes. I wore a wet suit and two pairs of seat pants.

5. the hip molds are seperate bags after you have the bottom fit. Then you have to sand/grind the rough spots so the glass lays over easily.

6. Using your butt as a mold you can squish excess resin out of the way. In other words lay wet glass on mold, cover with plastic, sit on it and wait. If you use epoxy it’ll take a longer time to cure and the thin sections will be flexible until fully cured. If you use ester resin things get hot pretty quick so you don’t want too much excess resin as it’ll pool under your balls and poach them.

7. Personally I’d suggest getting medium density minicell (most minicell you get is soft) and carve it into a mold then have it as a back up seat. M200

The problem I have with most production seats is that the hip plates are vertical from the seat with hip pads projecting down over the hip bones, if the seat and hip plates are a continuous curve you get a LOT more comfort when the kayak is on a lean. In other words the hip plates might be 5-6" wide with a cut-out for splayed out thighs but no hard corners.

When I did the whole fiberglass mold thing it was pure backyard construction that filled up two trash cans with garbage. If you used M200 and sanded it as smooth as possible with a flash of flame to remove the fuzzies you could coat it with tool-grip and have a reasonably slipper surface(when wet).

Nice source, though with epoxy and/or
minicell he will have no problem.

Good point about the shape of the
hip plates. Seems I’ve had to mess with them on almost every kayak, except the one where I made a minicell seat.

half done already
got regular old 2" thick pink foam insulation from Menards, shaped the seat and laid 2 layers of glass with epoxy over it. Working good so far.

Pink foam, I dunno. Will anyone be
able to see the pink when you get done?

planning on painting it
gloss black. I couldn’t find the blue styrofoam.

I’d recommend saving the original seat and make sure whatever you make can be removed. If you ever want to sell the boat you can completely destroy it’s value if it’s not able to be put back to nearly original condition.

Bill H.