Posted by JimM on July 22, 2002 at 07:01:13:
In Reply to: drilling hole in hull for depth finder posted by Steve on July 20, 2002 at 20:35:05:
I don't see any problem with your approach. If you're clever, you could cut the plug from inside, and not allow the cutter to penetrate the outside layers of cloth. Then the nice finish on the bottom won't be disturbed.
I don't think you need to build up the 1/2" thickness in 'glass. I think 1/4" would probably be plenty, and I don't think a round 4" hole will weaken the plywood. You'll probably be putting near the stern where the panels aren't bend much if at all. If it makes you feel better, you could put a doubler of plywood there, thoroughly epoxied in.
I put a sounder in my 15' fiberglass skiboat and put the xducer on the transom. That tiny little boat gets an awful lot of air under it, so it's not very reliable. I don't know if I'd be better off bonding it inside the hull. As it is, I'm afraid a water-skier might try to use the xducer as a step to climb in the boat!