thru hull fittings

[SkunkBoat]

I don't want to seem like I am picking on you but in regards to SS it really isn't a great choice for an underwater fitting on a boat that stays in the water. SS is only stainless in the air. Underwater for long periods, it can develop veins of corrosion internally. You may have noticed that on underwater screws holding your transducer. I know I have.

And of course there are different types of SS. 304 is the most common(cheapest) and most likely to have crevice corrosion. 316 is better. 304L and 316L are even better. Add to that the fact that its all made in China now and probably doesn't really meet the spec.

Propeller shafts on inboard boats are usually Aquamet or Aqualoy. I don't think you'll find a thru hull fitting made of that.

As for me, I think the best underwater fitting is NONE! The only underwater hole in my boat is the original bronze garboard drain.