Lewmar Superhatch lens replacement

[Ketchgould]

I rebuilt mine only to learn a year later a polycarbonate exists with uv inhibitors. Find that stuff and use it.

[Delancey]

Originally Posted by Ketchgould

I rebuilt mine only to learn a year later a polycarbonate exists with uv inhibitors. Find that stuff and use it.

Why use polycarbonate instead of the spec acrylic? Because it is more expensive? Or because it scratches more easily?

[Ketchgould]

I read it is much, much stronger.

[Delancey]

Stronger yes, but more expensive and less scratch resistant.

If the hatch was properly designed in the first place, and that design included the use of acrylic as a glazing material, then substituting a stronger material will provide no appreciable benefit to the use and performance of the hatch.

As it is, I replaced my thirty year old hatch lenses for aesthetic rather than structural reasons. In spite of the acrylic material having been significantly degraded with age, it had not failed structurally. At what point the crazing impacts the strength of the material enough for it to be a concern I couldn't say.

[mitiempo]

Originally Posted by Ketchgould

I rebuilt mine only to learn a year later a polycarbonate exists with uv inhibitors. Find that stuff and use it.

Polycarbonate is more flexible than acrylic. Bomar is the only hatch manufacturer that uses it. The hatches that it is used on have bars across the opening because otherwise when stepped on it deflects enough to break the seal. Acrylic is the choice of Lewmar, Goiot, Atkins and Hoyle, and many others.

[Guatinvest]

Hi Delancey,
This is a great tutorial. I am faced with repairing my Superhatches or replacing them. Since I live in Guatemala, replacement hatches would be very expensive, duties, etc. From your description I believe we can do a lens replacement. It would be very helpful to have the Autocad files, if you still have them. My forehatch measures 70x70cm interior.
Best
Jean

Originally Posted by Delancey

Couple final thoughts-

Cost to replace from WM was about $3,100 for my five hatches, not including shipping. Select Plastics was a little more plus had like a six or eight week lead time which just did not work for me.

My cost was $250 for the acrylic, $16 for the zinc chromate primer, and I think like $10 for the butyl tape from EBay plus about 16 hours of my time.

I decided to reuse the hatch seals. That wasn't me being cheap, that was me thinking these things are going to go in a landfill for the next 100,000 years if I throw them away, besides, the hatches don't leak at the seal so if it ain't broke don't fix it.

The seals themselves are made from a type of material called EPDM that is used for roofing. If I ever have problems with them I will let you know.

If you want I can save you a little time and give you my AutoCAD drawings, you can give these files to anybody who cuts using a CNC. PM me an email. My hatches were sized 60, 40, and 20.

[EqPierre]

Hi there Delancey; thanks for the extensive info! Me too I have to rebuild my 5 superhatches soon. I will measure the plexi as correct as possible to draw the cutting patterns, but if you still have the cad-files available, it would be a welcome extra safety check. Not sure about the sizes, but I have 1 big- 3 hinge hatch from approx. 66cm square, 1x 2-hinge - 54x54cm, 1x 36x49cm and 2x 29x29cm. The hinges and handles seem to work fine, the rubber seals I still have to check. Here's a picture of the hatches about 35y ago. And one from last year, when we started the rebuild.

[carlabunga]

Where did you get your polycarbonate?

[Blewbird]

Are the CAD files still avaliable? Looking at a 39 year old boat that has these hatches.

[Kraken 2]

Hi Blewbird,


did you manage to fix your hatch and did you get the CAD files from Delancey in the end?

Could you send them on,I would appreciate them a lot.


cheers
Matthias