Thru-Hull Solution
Hi Fred,
I agree with the other poster--I installed a new GARMIN Depth/Fish Finder with GPS and Maps and couldnt be happier. It had an included transducer that was designed to be mounted to the base of a trolling motor, but also had instructions to mount it as a thru hull (no holes to drill or worry about)--just as long as the hull is solid fiberglass and not with a wood core. The hull of my E29 is indeed solid fiberglass. Before I permenantly mounted it to a semi-flat region just forward of the keel, I put it in a zip lock bag full of water and wired it up. It worked perfectly!
So next I designed a permanent mount. The instructions suggested "slow cure" epoxy--but I have read that many others have used silicon as well with great results. I ended up cutting a 4 inch piece of PVC pipe with the same angle as the hull mounting spot, then with a piece of wire, I suspended the transducer slightly above the hull, correcting for the slight angle of the hull. The idea was to suspend it so that it pointed more straight down, rather to a bit of the side (had I glued it directly to the hull). I then mixed up 8 ounces of west systems epoxy and carefully poured it into the 4 inch PVC and then mounted the transducer--slowly pressing it into the pool of epoxy. I was very careful during the mixing and the placement of the transducer, to prevent any bubbles between the hull and the transducer.
I now have a permanent mount, without drilling any holes and it works perfectly. I only wish all my Do It Yourself endeavors turned out sooooo well!
I hope this helps!