Over time, older Catalinas develop a horrible screech when you slide the main hatch open or close. When we first got our boat, the entire dock knew every time we used the hatch. Not a great way to make new friends.
There are several “fixes” out there that try to lubricate the tracks that it slides in. Some are grease, and others are low-friction strips. These fixes rarely work, however, because the issue is not the surface-to-surface friction in the tracks. It is when the hatch rails becomes worn enough that the back edge of the hatch (where you can’t see it) no longer clears the top of the boat. When the fiberglass edge drags against the top of the boat, it sounds like fingernails on chalkboard amplified through a megaphone.
The real fix is to raise the hatch back up so that it clears. If your wear is slight, then the Teflon strips will probably work for you. They did not for us, so I inserted thin aluminum strips in the tracks and secured each with a single counter-sunk screw on the aft end. That lifted the hatch up so it no longer drags, and the screech is gone.
The trick is to use strips that are thick enough to raise it, but not so thick it binds.
The strips I used were too short to go the whole length, so I had to use two in each track. I later bought some that were long enough, but have not gone back and replaced them yet.
