…to plastic or nylon through hulls above or below the waterline. Second Star had two plastic through hull fittings, one a vent for the propane locker and one for the water cooled refrigeration discharge.
While upgrading the propane system the locker was removed along with the drain hoses, the plastic fitting couldn’t survive removing the hose before it broke. Fortunately, the fitting was located in a place where it would nearly impossible to reach, so the danger was mitigated by the location. However, it was clear that UV had taken its toll on the fitting, the plastic had severely deteriorated.
As a result of that experience, the decision was made to replace the refrigeration discharge with a stainless steel through hull. From outward appearances the fitting looked to be in much better shape than the one for the propane locker. Appearances can be deceiving. It took less than a half turn with very little pressure to break through hull. A stainless through hull is now in its place.
A metal, stainless or bronze, through hull is more expensive than plastic but considerably more robust. There are places to be frugal and save money on a boat, a through hull, even one above the waterline is not one of those places.