NONcomposite sandwich construction

[Surfdad]

Took a short break from building the sandwiches to build this quad. We've been messing with a TWP Bullet that I routed in boxes for a quad. On the last ride James ripped out one of the boxes, so...time to build a real one.

Single concave, 4'6", bat tail.

[Jason B]

How are you getting the tip bent up? Are you just shaving the foam off the bottom to make the curve? If so, how thick of a piece are you starting with?
I'm interested in trying to make my own this summer--I always seem to get myself way too deep into projects I know nothing about though and I give up

[Surfdad]

Hey Jason. I'm building using two different methods. All of the composite structures I bag to a rocker bed. I hotwire the rocker using masonite templates FIRST into a large block of 2# density EPS. This gives you an idea of what the rocker bed looks like:

[Surfdad]

I guess I've already used that picture, let me try another one.

[Surfdad]

As you can see in the above photo, the blank or core was 2" thick and 1# EPS. When you bag it to a high density skin, it contours to the rocker table, like this:

[Surfdad]

You can use billet foam (straight blocks) but I prefer to hot wire the shape into a thicker piece of EPS then the bottom of the core or blank mates exactly to this rockerbed.

The other type of construction is more traditional and is how I made this quad pictured at the beginning of the thread. You buy a close tolerance blank that has the rocker and outline mostly shaped. Sources for those include foamez.com and fiberglasssupply.com amongst others.

This project was an EPS blank which requires EPOXY for the resin. Polyurethane blanks and Ployester resin is easier to learn on. Billy of ASC is talking about biofoam which I've never used, but I've heard good things about. Anyway...the blank is more closely tied to an ocean surfboard and you'll wind up mowing quite a bit of foam for behind the boat.

[Jason B]

Nice! Very informative. Thanks.