Hi

I have to vehemently disagree with Jimbo's suggestion of using aluminum as the backing plate.

Use a piece of 1/32" (.031") thick G10/FR4 (this is a fiberglass-epoxy composite already cured). The aluminum will rot away (unless it is anodized first), very tricky to get a good bond, and is twice as heavy and stiff as the G10 - which more closely matches the resin/cloth your boat is built with.

For 1/32" G10 go to McMaster.com PN:8667K111 (6" x 6" for $2) or 8667K51 (12" x 12" for $3.95).

Otherwise all the other advice seems correct.

Also, a great source for quality cloth is: www.uscomposites.com. I highly recommend using the 4 oz 6oz S-glass.

I've done over 100 fiberglass repairs on foam cored boats, etc. E-mail me directly if you need more info.

Steven Bellavia
Hobie FX-1, Sail # 211