Paddlewheel location and hull thickness

Hi all,

I'm removing and cleaning the paddlewheel installation on my boat. It was an aftermarket installation by the PO and was a bit of a mess. Mainly, it was not flush with the outside of the hull and was a mess with silicon/sealant. I wasn't sure if it was especially watertight so I sealed it up to last to the end of the season but now I'm reinstalling.

I've removed and cleaned all the silicone off the paddlewheel transducer/fitting and the hole itself. I've noticed that the hull is not of even thickness where it's drilled. When it was installed previously the tightening of the threaded ring on the inside of the hull had pushed one edge of the transducer out on the outside of the hull. The owner had filled this gap with half a flat rubber o ring and smothered sealant around it, hence the messy finish.

My question is, what's the best way to keep the paddlewheel flush on the hull exterior if the hole is drilled through a section that is of varying thickness? Could i get a compressible flat seal for the inside of the hull that would allow for the difference?

Also, is ther anything I should do with the hole itself in terms of sealing before reinstalling?

Apologies for the long post and I hope it makes sense!

D.

I would definitely check the manual, or the perfect pass website, to confirm the existing hole is even in the correct location. Believe they are very specific on where the paddle wheels should be installed.