Best way to modify fiberglass?

[TooCoys]

Boat: 1980 Hunter Cherubini 27

The forward hatch on my boat has long been broken. The previous owner repaired it by placing 3/4" plywood over the original hatch hardware. The latches and opening mechanism was cut out, and replaced with a hardware store solution.

After a hasty measurement, I ordered a Bomar hatch that has an 18.5"x18.5" square cut out. However two days ago I realized that my hatch was actually a trapezoid shape with a cutout of 18.5" forward, 20.25" aft, and 19.5" long.

I've also found out through research, that the factory that originally made these hatches burned, and the molds were lost, and to date there is not direct replacement. So I will have to modify the opening.

I'm going to stick with the hatch I ordered, because the square is actually the closest thing I can find. However I'm trying to decide what the best way to approach the fiberglass is. Should I cut out a "shim ring" as I call it, and glass that in, or should I glass in the entire piece, and THEN make the cut out for the hatch?

I tend to lean towards glassing in a shim ring, because I can screw it in to the sides, and then glass over it, and it will reduce the amount of fiberglass materials and sanding needed.

I've never personally done any fiberglass work, but I have watched my father repair his shrimping boats in the past.

Any advice, or suggestions on the matter would be appreciated. Below is a crude diagram that I made to hopefully illustrate my ideas.

[Tayana42]

Before modifying your deck try Select Plastics. Tony is very helpful and may be able to make a custom hatch for a reasonable cost.

http://selectplastics.com/?page_id=17

219 Liberty Square
East Norwalk, CT 06855
Email: anne@selectplastics.com
Phone: 203.866.3767
Fax: 203.866.3948
http://www.selectplastics.com

[TooCoys]

Originally Posted by Tayana42

Before modifying your deck try Select Plastics. Tony is very helpful and may be able to make a custom hatch for a reasonable cost.

Marine Hatch Repair – Selectplastics

219 Liberty Square
East Norwalk, CT 06855
Email: anne@selectplastics.com
Phone: 203.866.3767
Fax: 203.866.3948
Selectplastics – Selectplastics

The hatch that's on the boat is beyond repair, and I'm sure that a custom hatch would probably cost more than a couple hundred.

The bomar hatch that I bought was $382.

[UNCIVILIZED]

Most decks & cabin tops have a bit of crown to them, so mounting a new hatch can take a bit of planning. Were it me, I'd probably build a square or trapezoidal base out of FRP on a work bench/mold table. And then bond it in place, using the epoxy base casting method. With or without adding additional fiberglass tape or tabbing to assist with securing it in place.

Do make sure to round your corners, inside of the base, as well as those on the bases external sides. And bullnose or ease every radii that you can. Then once the new base is in place, you can fit the hatch to it. Measuring to ensure that everything is either level, or mounted at equal angles of cant on both, or all sides.

Oh, & now's a great time to build a breakwater for it, possibly to include an attachment system for storm covers, & or wind scoops. About which there are some good threads archived here on CF.

[Tayana42]

That's a good price but it doesn't include modifying the deck. It might be worth a phone call to get a price just for comparison. What ever you decide, I wish you the best with your project.

[TooCoys]

Originally Posted by Tayana42

That's a good price but it doesn't include modifying the deck. It might be worth a phone call to get a price just for comparison. What ever you decide, I wish you the best with your project.

I know. I'm stuck between a rock and a hard place.

There aren't any more drop in hatches made, so this seems to be a very very common problem with this model of boat. There are tons of threads on it on sailboatowners forum, and the common solution is always some kind of modification.

My rock is that there aren't any more drop in replacements, and my hard place is that fact that I don't want to spend hundreds and hundreds of dollars.

[TooCoys]

The other option is to get a 20 1/4" square hatch, and cut the deck into a square.

I'm just hesitant to cut my deck up.

[JPA Cate]

And I'd like to second UNCIVILIZED's mention of hatch breakwaters, or dams. All our three of our hatches have them, and I love them. They never leak.

Ann

[UNCIVILIZED]

Is modifying the boat really that big a deal? And before you answer, consider that there's really not a thing as a deck that's too stiff in the vicinity off hatch opening. Though the reverse is all to common, & it can cause major headaches both in terms of then having to repair things over, & over again. As well as it's being an impediment to getting a good seal on the hatch. And since hatches are generally located directly overtop of prime living spaces, including bunks, saying that having them leak sucks, is a vast understatement.

Note that Lewmar hatches, their Ocean range in particular, have been around almost forever. And to my knowledge, their dimensions rarely change. Which, if they do, it ain't by much. So they're a decent way to go for hatches due to this. As well as due to ruggedness, & availability of parts for them.

[TooCoys]

Originally Posted by UNCIVILIZED

Is modifying the boat really that big a deal? And before you answer, consider that there's really not a thing as a deck that's too stiff in the vicinity off hatch opening.

I'm not sure that modifying the boat is a big deal, but it's a big deal FOR ME. Once you cut away, or modify any part of a boat, you can't put it back.

Whereas, if I modify the hatch, and not the boat, I can always go back and redo what I've done.

To me, modifying the boat itself compounds the issue, or at least potentially compounds the chances of error.

[Three Sisters]

I'd glass over the original opening as it is larger on three sides. Then recut for the dimensions of the newly purchased hatch. And the perfect time to add the water shed, hand holds, locks and other accessories as needed. There may be other construction on the interior that would change my mind on this approach.

Also, the threads you start are very good, you come back and repost !



partial quote:

Originally Posted by TooCoys

Boat: 1980 Hunter Cherubini 27

After a hasty measurement, I ordered a Bomar hatch that has an 18.5"x18.5" square cut out. However two days ago I realized that my hatch was actually a trapezoid shape with a cutout of 18.5" forward, 20.25" aft, and 19.5" long.

[TooCoys]

Originally Posted by Three Sisters

Also, the threads you start are very good, you come back and repost !



partial quote:

I remember my 4th grade teacher calling me "The Questioneer" all the time. I tend to ask 4 million questions, and obsessively research topics, before I start in on any application. I have to build a process in my mind before I ever start doing anything. Once I have a mental picture of what I want to do, and how I want to do it, I can usually accomplish anything that I try.

[Three Sisters]

Originally Posted by TooCoys

I remember my 4th grade teacher calling me "The Questioneer" all the time. I tend to ask 4 million questions, and obsessively research topics, before I start in on any application. I have to build a process in my mind before I ever start doing anything. Once I have a mental picture of what I want to do, and how I want to do it, I can usually accomplish anything that I try.

Excellent. And as you say, a greater chance of success.

[jimbunyard]

If you're set on using the Bomar hatch, probably the easiest and cheapest way would be to get a piece of 3/4" coosaboard, cut it to fit the trapezoidal mount for the existing hatch (say a 1/4" shy, and matching the existing chamfer), glass both sides, gelcoat the upper side, and laminate the lower side to the existing hatch cutout, then make the cutout for the Bomar hatch. Done carefully, the only grinding on the boat would be the flange where the new hatch mount and old hatch mount meet...

The actual outer dimensions of the existing mounting pad would be helpful.

Lewmar offers a trapezoidal hatch close to your dimensions; it's called a 'Size 65', P/N 39965030. You can get the dimensions here to check if it will fit:

https://www.google.com/url?sa=t&rct=...7fKUMRXzP10fKg

[minaret]

How about some pics?