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Discussion Starter · #1 ·
I am installing a new lewmar hatch to replace my old wood framed hatch. However the dimensions are different. The old hatch is square and therefore is longer but slightly less wide. My question is is there still a way to mount the new hatch even though the hole where the old hatch was is longer. If so how do I do that?
 

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It depends where the screw/bolt holes for the hatch are, are they “out” of the fiberglass on the longer side?
I would remove the core between the top and bottom fiberglass laminates by about one inch, extending into the other two sides to serve as a lip.
Cut/plane and insert a piece of wood - oak or any other hardwood to fit within the “sandwich” and to protrude by as much as required for the new hatch. Mix epoxy, some unfilled to encapsulate the wood for protection, and mix some with Cabosil or similar to bond the wood to the top and bottom deck laminates. Clean the "gap" with vacuum and acetone and insert the epoxied wood.
Once the epoxy is cured, place the hatch in place and mark the excess wood that you need to trim. Sand the exposed wood and put another coat of epoxy for additional protection. Install the hatch with your bedding compound of choice - either Butyl or Sika 261.
 

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Discussion Starter · #4 ·
I don't have a cored deck contest made the 30 without a core the deck is solid glass so taking that into consideration how would I be able to sandwich it if the laminate is solid. Also the former hatch doesn't seem to be bolted it seems to be laminated to the deck. There is the outer part of the hatch and an inner fiberglass lip to allow water to flow thru without reaching the interior in theory.
 

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Pictures would be useful :)

I would think that you would need to build a base for the new hatch.

I'm assuming that it's a Lewmar aluminium hatch, these hatches need to be installed on a perfect flat surface.

Make the frame so i cover your old cut out.
 

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Discussion Starter · #6 ·
Unfortunately I won't be going up to the boat until March and have plenty of photos of the boat but none of the hatch. So what you are saying is to epoxy a block of wood to the opening and then mount the hatch on that or would it be better to glass over it first
 

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...Make the frame so i cover your old cut out.
...So what you are saying is to epoxy a block of wood to the opening and then mount the hatch on that or would it be better to glass over it first
In the case of a solid deck, a wooden frame would be the way. This "under frame" would be a bit wider than the hatch to allow more "grab" on the deck for the sides that are larger. This hard wood frame, needs to be carefully made, it is not a block of wood - it needs to allow for the deck camber at the bottom and be flat on the top to accept the hatch frame.
 

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In the case of a solid deck, a wooden frame would be the way. This "under frame" would be a bit wider than the hatch to allow more "grab" on the deck for the sides that are larger. This hard wood frame, needs to be carefully made, it is not a block of wood - it needs to allow for the deck camber at the bottom and be flat on the top to accept the hatch frame.
And if the deck is single skin could be an option to make an inner frame also.

The "under frame" can be made of
-hard wood
-some sort of plastic material
-Fiberglass with epoxy or polyester
 

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Discussion Starter · #11 ·
Thanks for the link the question I then have is how would I bevel the bottom of the wood or glass to fit the curvature luckily my hull is not massively curved but is enough so to require the beveled base. If fiberglass is a better option is it possible for me to mild it or do I need a ready made plate
 

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Thanks for the link the question I then have is how would I bevel the bottom of the wood or glass to fit the curvature luckily my hull is not massively curved but is enough so to require the beveled base. If fiberglass is a better option is it possible for me to mild it or do I need a ready made plate
You can mould it but is much less work to start with a plate with an even surface.
 

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Ok so where do I buy fiberglass plates and how do I make it so it fits the curve exactly and isn't over or under curved
To make whats being called the "under frame" out of wood, you trace the deck on to a piece of plywood to get the camber template at that point.
You hold a piece of 1/8 or 1/4" plywood over the place where the frame will be and use a level on top (assuming your boat is somewhat level) to keep the plywood horizontal, then trace the deck over to the plywood using an opened compass with a pencil on one side. Mark the side and repeat for the other 3 sides. Now you have a deck camber template for the hatch area.
Then transfer this to the wood and cut it with a saber or band saw. Mind you, the curvature will be minimal, so you may not even have to cut, just heavy sanding may do for the ones athwartships and a bevel for the side ones. Small mistakes will be taken care of by the epoxy or bedding compound. Its actually easier to do than to describe. For the hatch installation, take a look at this site, go about half way down the page under "Deck Hatches"

Far Reach Voyages Home Page
 

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If you have to "fill in" the old hatch frame a little because the new hatch is smaller than the old one (the original square hatch is longer and wider than the new one, according to the original post) you may want to use something like "starboard" or some other material that will bond well to the existing cabin top or hatch frame and which won't compress or rot. When we replaced our cabintop hatch, it was a bear to get out, and the opening in the cabintop got dinged in the process. Our new hatch wasn't the exact same size as the old one either, but we managed to drill into sufficiently solid material to make it work. We ended up having to glue trim around the inside of the opening to cover the dings. We are much happier now with a hatch that is strong enough to stand on when we need to, and which doesn't leak.
 

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Discussion Starter · #18 ·
Ok so as I understand it I take a thick peice of g10 or fiberglass or a hardwood and I bevel the bottom of it to fit the curvature of the hull.

Then I make a cutout in the material for the hatch.

I then sand and clean with acetone both the deck and the material.

I then use epoxy and glass two layers of mat to the deck and then epoxy the material to the mat and using pressure and weight let it set.

I then fill in the sides with filler.

And then mount the hatch. Is this correct?
 

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Kind of..

Ok so as I understand it I take a thick peice of g10 or fiberglass or a hardwood and I bevel the bottom of it to fit the curvature of the hull.

You take 4 pieces, I would say no less than 5/8 thick, 3/4 would be ideal.

Then I make a cutout in the material for the hatch.

Then you join the 4 pieces - making a square, flat sides up.

I then sand and clean with acetone both the deck and the material.

Yes, sand the deck first.

I then use epoxy and glass two layers of mat to the deck and then epoxy the material to the mat and using pressure and weight let it set.
I then fill in the sides with filler.
And then mount the hatch. Is this correct?
I would mount the wood/whatever sub frame and the hatch at the same time, caulking under and over the sub-frame and thru bolting.
 

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I removed a wood hatch and replaced with a Lewmar on a teak base. The base can be made to fit over your deck opening as needed. In my case, I made it like a four sided picture frame with the interior opening sized to fit the Lewmar, and outside sized to overlap the deck opening. Hardest part for me was the shaping of the bottom of teak base to exactly match contours of the deck. In my case it is a hand laid deck and not really symmetrical either fore/aft or side to side so each side had to be shaped separately. Set with most of a cartridge of Sika sealant 3 years ago an no leaks yet. That stuff is really messy to clean up so be careful. My deck is solid in that area so I was able to through bolt. If the pictures come through you can see the deck opening after removal of old hatch and slightly cutting down the fiberglass lip, before starting to fit the teak frame.
 

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