Ok, I unscrewed one of the ports, the cutout size is 7-1/2'' by 14-1/2''. I can't find the exact size, but I guess I can get bigger versions and cut a little bit.
So far on my list:
Bomar Molded Gray Series Portlight
What port do I need? by Beckson
- number 714
There is also one from new found metals:
New Found Metals - The New Self-Sealing TriMatrix
- 7" x 15"
Did anyone try any of these? What do you think I should buy? One thing to note - the walls on the boat are pretty thin, they are basically two sheets of fiberglass, inner and outer one with air in between, so looks like for the newfoundmetals one I would need a teak spacer.