Re: 70 Carefree
Absolutely! You'LL never fix that with MarineTex. You need fiberglass or epoxy resin and cloth to get a solid, lasting repair. It's really not that hard ... no reason for your season to be over.
You should be able to fix that in a day easily.
Sand off all that MarineTex and start with clean glass on the hull. I really can't see what you have there but I would use at least 2 layers of cloth. More if the crack is really bad.
Glassing upside down isn't fun but it is doable. Saturate your cloth in a tray and let it sit for maybe 10 minutes and allow the resin to "proceed". Paint resin onto the area to be repaired and when the patch resin starts to become a little less viscous (indicating curing has begun) put it on and get it positioned. You can use an "ice water bath" to control the cure rate if it's too hot outside. Aluminum throwaway baking pans work well for this kind of work.
A layer of wax paper over the top of the patch will allow you to smooth it nicely with a squeegee. When cured the wax paper will come right off. Polyethelene plastic works too.
Measure your resin and hardener VERY CAREFULLY and avoid later curing problems. Don't just "wing it" ... your patch may not cure! STIR WELL!
