Can " tannoy" vents ever be waterproof?

[Seajet]

I have a dorade type vent on my 7m boat, always waterproof, boat kepted in beautiful condition inside, all grip dry and shining.never any bilge water either.

Sorry to rain on your parade - somewhat literally ! - but dorade vents are not waterproof when immersed, ie the boat inverted.

Yes this is a worst case senario from the realms of books like ' Heavy Weather Sailing ' but as it has been proven it can happen, that is what I and I think others here are alluding to when saying ' waterproof '.

If I had a boat with dorade vents again now I'd at least fit inspection hatches over the cabin inlet holes, and for serious sailing the same to go over the dorade boxes with the cowls removed.

I think there were accounts in Adlard Cole's original & best editions of Heavy Weather Sailing of dorade boxes themselves being swept off in extreme conditions...

 

[Binman]

Not much to worry about if that happens, and the hatch way is open,