i just got a used boat and i found a pin hole size leak where a old transducer screw was installed what is the best way to stop the leak type of sealer to use. its a fiberglass bonita boat.
Marine tex epoxy putty would be best in my not so experienced opinion, I just did some patching, its great stuff hard as a rock even sands and paints nicely.
A bolt with 3M 5200 caulk is an option.
funny just yesterday I plugged old transducer holes on my aluminum boat. I just put a closed end rivet with 3M 5200 caulk. Im not worried.
Fiberglass,alunimum? If alunim,just put some 4200 on a bolt and put it in,with a nut and washer on the inside-stainless of course. Or have it welded.glass,epoxy,and paint to match.