Duck boat patch????

[lungslicer]

I have a older fiberglass duck boat that is leaking from a couple large thin cracks on the bottom. Does anyone know of a material that I could use to fill the cracks with other than fiberglass resign. I want to use something that is easier to sand down. Would auto body filler (bondo) hold up?

[Surface Tension]

If you use Bondo it'll crack again. You'll need fiberglass cloth and resin on the crack. I'd do both sides(inside and out). Surface prep will be important, it'll need to be paint free, scuffed, and clean.