A 1/4″ hole is big enough. It need to align with this hole
here but doesn’t need to be this big. Lets the exhaust
pass out for starting.
Rich Cerankowski (bigrichsoldoutboardparts on eBay) was
reproducing the rubber grommet for the water tube at one
time. I’ve made my own as well. Check the home centers or
hardware stores for a grommet to start with if you want to go
that way.
Tubs.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.