Transducer size change

[billcole]

Hi All. Due to an instrument change I need to replace a transducer with a new one about 1/2 inch less in diameter. I'm trying to decide what's the best thing to do with the existing hole in the hull. The choices seem to be..
1 )Leave the old transducer there and drill a new hole nearby to fit the new one. I'm not too keen on doing that, although it would probably be the easiest option.
2) Remove the old transducer, repair the hole and drill a new hole nearby to fit the new transducer.
3) Remove the old transducer, repair the hole and drill a new hole through the repair to fit the new transducer.
4) Adapt the new transducer fitting to fit the oversize hole left by the old one, maybe by getting a pair of big "washers" made up to go inside and outside. If so what from...stainless, bronze ? would at least one need to be a "top hat" section to stop the transducer ever shifting sideways in the hole, or would epoxying them to the hull be enough. Both fittings are plastic (I want to replace an old Navico fitting with an Echopilot forward looking sounder transducer), and the hull is GRP.
All advice and suggestions welcome. Thanks

 

[savageseadog]

I've thought about this problem myself. Reckon the only solution is to refill the existing hole and drill. It might be possible to put a piece of drainpipe or similar of the required diameter through the existing hole and fill with an epoxy and fibre mix but you'd need to chamfer the hole both sides and use some woven mat to bond it to the surroundings. If you've put some realease agent on the tube just pull out and presto you have a smaller hole.

 

[Guest]

There are only 2 Options:
1. Use the bronze optional fitting as it is larger.
2. Epoxy and glass the hole up and then re drill.

You will probably need alignment blocks to get it to look downwards. So these will spread the forces onto the good hull. Hardwood or Tufnol G10 (light green Epoxy glass, not the brown stuff)

The instructions are very clear:
"A hole in the boat must be taken seriously! - If in doubt use an experienced shipwright."