How to Bed a Transducer

[weephee]

I just drilled a 2 3/8 inch diameter hole in the lower side of my boat in order to install a depth transducer. This transducer is not installed flush with the hull but is proud. The solid core hull at this point is approx 1/2 to 3/8 inches thick. When I dry fit the transducer there is a 1/16 inch gap top and bottom of the transducer ring to hull due to the curvature of the hull. The lateral edges are tight. Question is what do I use to seal the transducer to the outside of the hull and should I be worried about this 1/16 inch gap top and bottom. I plan to make a backing plate for inside the hull. There is a large rubber ring that fits between the tightening nut and the hull or backing plate. Thanks
Larry

[scottyt]

the easy option is to bed it with 4200 and just wipe of the excess with your finger and call it good

the harder option is to build up a flat spot with thickened epoxy, then bed it with 4200.

you could also sand a slight flat spot for it, say split the 1/16 difference. the backing plate should be epoxyed on so no real loss in strength. then bed it in 4200

get the hint yet, just bed it with 4200 filling the gap you will be using it anyway and 1/16 inch is not a big deal.

[weephee]

Thank you for your reply. I already have some 4200 so that is what I'll use. Thanks again