I have 16 recessed portholes in the hull
, which swing inwards to open.
(I think the primary reason they traditionally swing open is to have an internal securing point when opened and to make them easy to remove/replace at sea) (Also the shins)
They have a thick heavy formed rubber gasket inset on the window frame which closes on the thin edge steel
collar that forms the recess from the hull
. When hard pressed to weather
, some are underwater but do not leak a drop as the heavy duty wing nuts compress the rubber deep into the collar edge. The whole arrangement is very heavy duty and solid..... yet simple.
The secret is to maintain the heavy rubber gasket by using a light oil
to keep it flexible.
About every 5 years in the tropics I replace the gasket when the edges start to craze or crack.
You can see by the angle, there is no problem with water
I like this clean style because you have no corrosion
issues due to external flanges and the recess is more forgiving in light rain for keeping rainwater out.