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Old 22-01-2015, 09:32   #1
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Cracked Lewmar Hatch Frames

I took my Lewmar Superhatches apart to replace the rubber support cams. I found the aluminium frames were broken under one hinge on each hatch.

I assume this is a design flaw and the frames may crack from the stress of the difference in expansion between the plastic lens and the aluminium frame. They leak in driving rain and I doubt if they can be successfully sealed.

Has anyone had them welded and have they re-cracked or is it impractical at this point to overhaul them?

Has anyone replaced the 60 size Superhatches with a different brand?

I'm tempted to replace them with Vetus hatches as they are a lot less expensive and appear to be well made.
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Old 22-01-2015, 09:42   #2
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Re: Cracked Lewmar Hatch Frames

I suspect the design flaw is in the coachroof of your boat, not the hatches themselves. If all of your hatch frames have cracks in them, that tells me that there is torsional stress on the frame that is the result of the coachroof flexing. If you're not in a position to stiffen the structure then I suppose your other alternative is to install more flexible hatches. :\

I have never heard of this being a problem with Lewmar hatches in general. There are four 28 years old Lewmars on my boat and while the acrylic on a couple of them is crazed and in need of replacement, the frames are just fine.
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Old 22-01-2015, 09:56   #3
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Re: Cracked Lewmar Hatch Frames

I recently replaced the lens on my Super Hatches and one of my frames was cracked at the weld. Had a buddy weld it up no problem. Good as new. Link to thread below.

Welding means a bit of grinding which means you will be losing the anodizing in that spot but that was not something that concerned me. If you want it prefect you will have to re-anodize which is not really a big deal, I can advise you if need help.

The newer Lewmars have a different radius so if you replace you will have a finish issue at all the corners inside and out. Regardless I would repair rather than replace. Cheaper and why throw something perfectly good in the trash? Not what the manufacturers want to hear so you won't get any help from Lewmar.

Good luck!

Lewmar Superhatch lens replacement
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Old 22-01-2015, 10:14   #4
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Re: Cracked Lewmar Hatch Frames

Delancy

Thanks that is a great tutorial on rebuilding the hatches.

My problem is that we (SWMBO and I) are staying on the boat full time and I don't see doing that work on the dock as viable. I was tempted but the cracked frame is a deal breaker. We haven't been in Vancouver long but the prices I've found for acrylic are a bit of a shock.

Maybe I could send them to you to rebuild? Maybe this weekend?
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Old 22-01-2015, 11:19   #5
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Re: Cracked Lewmar Hatch Frames

My wife and I also live aboard, I made one plywood hatch each for the different sized hatches I have and did the work in phases. You could make plywood hatches for all of them and do it all in one shot but would mean living in a cave for as long as it took you to do the work. Regardless, I wouldn't let that be the deciding factor.

Besides the cost of flat-out replacement there is the finish issue I mentioned. Not sure about how the Vetus would fit but the newer Lewmars have a larger radius in the corners which means you will have a gap between the frame and the deck that will need to be filled causing a gel coat matching issue as well as a bunch of glasswork, maybe you are planning on repainting your deck?

Besides that, consider you also will have labor involved removing the existing deck frames. Depending on how they are bedded (3M 5200?) could require whole lot of work which can be avoided by simply repairing instead of replacing.

As far as material cost goes, I got my sheet of acrylic for $250 from a new sales guy who was eager to get new accounts. Here in the US you should be able to get decent Mexican product for $350 and I expect thanks to NAFTA that prices in Canada should be about the same. After that it's your labor, what's that cost?

Maybe not a dockside project but if you can find a garage or shed you don't need a big space or much skill to do the job right. New hatches aren't cheap, nor is painting a deck and having to remove existing and install new. My money is on repair and I'd give you every encouragement to go the route because depending on how many hatches you could be talking a difference of thousands.

Cheers
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Old 22-01-2015, 11:29   #6
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Re: Cracked Lewmar Hatch Frames

Also, as far as why it happened. The alloy extrusion that is used is either 6061 or 6063 series (thanks for the info Lewmar, NOT!). Welding causes a heat affected zone and the weld itself tends to be a bit brittle compared to the surrounding metal.

Bad design because Lewmar tried to hide the weld beneath the hinge strap for cosmetic reasons but guess what? That is where all the stress is from the rubber support cams that are a part of the hold-open mechanism. Newer Lewmars moved the weld location and don't have this problem.

Also I think trying to latch close the hatch with something like a loose line under it could be a contributing factor. Like I said, had a buddy weld my cracked frame up and haven't had any problems.
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Old 22-01-2015, 11:34   #7
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Re: Cracked Lewmar Hatch Frames

I thought a lot of those hatches were cast aluminum...?
I guess I'm thinking of the old black ones with the cross hatch pattern grid supporting the plastic lens...


Probably pre late 80's.....
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Old 22-01-2015, 11:45   #8
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Re: Cracked Lewmar Hatch Frames

The black ones with the grid are cast aluminum made by Bowmar. I believe these are also one of the few that use a polycarbonate lens. Polycarbonate is less stiff than acrylic, hence the need for the grid to support it.

The Lewmars are formed from an aluminum extrusion and welded.
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