For Nauticat window leaks, the leak comes from two sources only: 1. From the gasket that the window glass itself is enbedded into. The glass has a gasket around the edge and then the aluminum frame is bent around the glass/rubber, or 2. From a leak between the aluminum frame on the outside of the boat and the fiberglass hull. The aluminum frame on the inside and the foam rubber on the inside do nothing but make it look pretty and hold the window tight against the fiberglass on the outside of the boat.
To correct #1: Look carefully and see if the water is around the rubber next to the glass on the inside of the boat. If it is, cut away the rubber on the outside of the window, use a razor blade and just cut down to the glass all around the aluminum frame. Then but a bead of sealant, I use 3M 101, but am looking for something else as it only last about a year. Be careful not to confuse condensation with the water leaking around that rubber seal about the glass.
To correct #2: This is more of a problem. First, remove all the screws from the retaining ring inside the boat. Once that is gone, the window should still hold in place. Then, on the inside of the boat, look at the crack between the window and the hole that was cut in the hull for the window. Look carefully and you may be able to see daylight (yes, Nauticat does not do a very careful job sometimes in cutting out the window hole). That will obviously show where a leak is.
If you see daylight or not, just push out the window and set it off to the side. Clean up the hole and window. Get all the residue off. Then either buy an external gasket from me or, better yet, use a good sealant and put a bead around the window so that it makes a good seal. In the past, I have used a 3/4 in x 1/8 in strip of tar that you could get from the car window repair shops and then just push the window back into the hole.
Oops, before you push the window back in, check out the hole cut in the hull itself. I found that water would defeat the outer window seal and then come in, only to drop into one of the cabinets below the window thru the wall itself. It seems that Nauticat does not seal the opening so that when you look at the thickness of the hull, you see fiberglass outer wall, several layers of plywood and then the inner layer of teak on the inside of the hull. Water can seap down thru all that, what a mess. I just used some fiberglass resin to seal each of the window cutouts. Now the water, if it defeats the outter gasket, will make it all the way into the boat and you will see water dripping down from the aluminum inner frame down the teak.
I am in the shopping mode to find a better sealant, it needs to be a good removable, UV resistant sealant that bonds to fiberglass and aluminum. Anyone knowing of the right sealant, let me know.