Bow Hatch - making cutout smaller

[BRAZO]

I need to reduce the opening size on the cutout for the bow hatch and I need some guidance.

My thought is to clamp the hatch frame upside down with the "screw" flange on the inside of the boat.

Then I would line the hatch frame with duct tape or something else??? to keep the epoxy from adhering to the frame.

Then I'd pure in thickened epoxy in-between the original cutout and the protected frame.

This would then create a new perfect opening and I'd take the frame out and install from the outside.

Question: Any thoughts on what to line the hatch frame with in order to be able to pull it out easily after the epoxy hardens? Any thoughts on why this would not be a good idea?

Thanks for your help.

[jkidd]

I think I would make a template. I would probably worry about messing up the hatch and having to buy a new one. Plywood is cheap.

[thataway]

The opening does not need to be "perfect"--in fact some hatch flanges have a very slight taper and this could be adverse to what you want to do.

I agree that pouring in epoxy is not the best way. Also you have no matrix support for the epoxy--and that is why I use glass stips.


This photo is the forward hatch on the Tom Cat when it was less than a month old. Notice that I have used mostly hand tools--an exacto knife and a rasp to fair the sides of the hatch--in the photo the new holes are drilled--and about equal spaced--also the top surface needs to be fair to the hatch flange. Before several screws did not go into the glass at all.
The entire edge was under cut a small amount with a Dremmel tool and filled with thickened epoxy before the strips of glass were laid around the inside of the hatch cut out. The width of the glass strips was about the same as the depth of the deck where the hatch goes. I laid in about 3 pieces of glass all of the way around, then faired with medium density filler and epoxy--with some white pigment to make it cosmetically similar to the original polyester. None of this shows from the exterior.

[Ed J]

I would agree with making a plywood template instead of using the hatch as a mold. Use waxed paper or heavy duty plastic wrap (Saran Wrap) as a barrier to keep epoxy from sticking to the plywood. If reducing opening by .500" or more I would consider glassing in thin marine plywood strips to fill some of the gap and undercutting the existing opening to create a keyway effect for additional strength.

Ed J

[BrentB]

Bob

Do you use the same tools to remove Bostic?

[thataway]

Removal of Bostik products: Generally I peel and cut the sealants used inside of the boat (my Tom Cat had almost every fitting smeared with one of the silicone based Bostik sealants). No reason to use a rasp or sand paper etc.

I am not sure what is being used now--Bostik makes almost as many sealants/adhesives as 3 M!
This is just the marine catalogue:
http://www.bostik-us.com/files/catalogs/M26_Marine_Products_W.pdf

There are urethane, isocinate, silicone and other base products. So the removal of each type of product may be different. If it is one of the urethanes, I lke ot use a piano wire which is heated to cut thru the sealant. There are also debonding agents for silicone and urethane adhesive/sealants.

[BrentB]

You worked hard removing the Bostic sealant form the TC.