Got burned on a jon boat

Well My first try.
I put jb weld i made a long cigar shaped piece an placed it in the bottom an top of gash. let it dried for like 2-3 days I checked it today no water leaked put a little pressure on back plate an snapped the jb weld. THe back bench seat the rivets arent holding the back seat down so my guess theres to much flex. Im going to take the rivets out an take it to a welding shop an have them tac weld seat to floor an cover hole!

That'd work too. The issue is that if the JB weld don't stick out of both sides of the whole a bit, it can pop out just like you said.