Hi Simon,

My son has an Intercepter 650 and has gutted it to close the tunnel, to get a "normal" Vee bottom.
He plans to build in a electric motor, so not much reinforcements are needed.

All the glueing is done with ABS glue (yes the stuff for the plastic kits) or Stabilitt Express.

I am allowed to help, and we doubled the bottom with ABS sheet, to have a solid base for the motormount.

If I'm correct, ABS does not respond well to nitro fuel, so you'll have to paint the interior, with nitro resistant paint, to avoid disaster.

You can use glasscloth and epoxy resin, but you'll need to "stick" the first layer on/in to the ABS, using acetone, this solves the ABS, and holds the glass cloth as a base for "regular" epoxy/glasscloth.

Double your hull first with ABS sheet, the original is too thin and will deform because of the weakening from the acetone.
Make sure to use as little acetone as you can, don't soak the ABS, or it will weaken and deform. Let it air out completely.

Hope it helps.

Regards, Jan.