I removed all my portholes while having my deck & cabin painted.  Now it's time to re-install them.

Thing is, I cannot figure out the best way to caulk them.  My plan is to use polysulfide around the barrel/bung of the inner porthole where it is in contact the cabin wall.  I am going to 'countersink' (bevel) the opening on the outside and apply a ring of butyl tape around the opening on the exterior.

The exterior bezels are easy... The portholes are another matter. They fit rather tight within the openings so if I applied caulk to either the porthole barrel/bung or opening (or both) I think the caulking will just scrape off as I push them through.  The result being I've got an accumulated 'mass' of caulking on the inner ring to deal with.

Is there a trick to rebedding portholes to get a tight waterproof seal?

Bud Taplin wrote:

You gotta stop and think about this.  The water has to get in from the outside.  So if you just caulk on the exterior around where the water can come in, that will stop it. 

NOW WHY DIDN'T WE THINK OF THAT SOONER ????????

Because it makes too much sense?

I'm a huge fan of K.I.S.S. and doing it that way would certainly make it much simpler/easier to maintain, keep the seal water tight over the long term.