Below is a cut-and-paste of a post I made several years ago on this topic for the ports. This pertains to ports that have leaks due to old/compressed gaskets between the clear plexiglass and the port frames. Subsequently I have done the same to my hatches as well. We have had three moderately good rain storms in the San Francisco area so far this year. My ports and hatches still aren't leaking one bit.
Here's the previous post:
Maybe Apply New Gasket Material Over Old?
The port gaskets on my 1980 Hunter were leaking when I bought the boat 1.5 years ago. An inexpensive fix stopped the leaking and the fix looks like it will last. The plexiglass window ports on my boat are the type that swing open to the inside, hinging at the top. The original gaskets on the frame had become hard and compressed. What I did was:
- The original gaskets are affixed inside a channel all around the perimeter of the port frame against the which the plexiglass is dogged tight against. I left the old gaskets in the channel, but with a razor-sharp box cutter knife, I shaved these original gaskets flush with the outside of the channel.
- I then wiped the shaved original gaskets with lacquer thinner to clean off any dirt/grime/soap/wax and to "reactivate" the hard foam.
- Finally I applied a high quality stick-on gasket tape made by MD directly on top of the old shaved/cleaned gasket. (MD gasket tape is available at all hardware stores. This is the smooth surface foam type -- not the porous foam stuff. It comes in a double band, and is hollow in the inside. The two sides neatly split when the two sides are pulled apart. Comes in brown and white colors.) Make sure that the two ends of the new gasket tape around the perimeter meet on the top side. Don't stretch out the stick-on gasket as it is applied.
This solution might be worth a look-see for your situation. However suggest that you do only one port first to check if it works .... before doing the others.