"I've never had a whole bu
"I've never had a whole bunch of luck with thro hulls. My transom mounts on the other hand have performed admirably.
The key with any transom mount is to be sure that the drilled holes in the transom are truly sealed to prevent water infiltration.
I've heard others mention that you overdrill the hole size required, fill the holes with 3M 5500 and then redrill the holes to the smaller size required once the 5500 has set up. I've often wondered how you know that you've drilled in the exact centre of your previous hole?
I drill the hole size required for the stainless screw being inserted, fill the hole with 5500, and insert the screw. This stuff is almost bullet proof and will give a seal about as good as you will ever get. If you ever have to remove it, be prepared to drill it out. However, once that's done, refill the holes with the same product, allow it to cure, and you'll never have to worry about water infiltration"