Replacing Acrylic in Forward Hatch

[waterdog]

Lewmar doesn't recommend replacing the acrylic in the forward hatch.    They feel you need a freshly anodized frame and climate-controlled room to do an effective job.   And I have to say, I was impressed with the job they do.   There was no evidence of any water penetration through the old seal.   However I needed hatch acrylic and I didn't feel like buying a new hatch or trying to export the old lid to one of the vendors who specialize in replacement.   So I did it myself.

Materials and tools required:

24" square piece of 12mm (1/2") acrylic (use polycarbonate if you like, but do your research first!)
Tube of black silicone (I know that Lewmar uses some special goop from GE, but I prefer silicone - suit yourself)
Masking tape

A sturdy utility knife (and a dozen fresh sharp blades)
Drill
Router with flush trim bit

Procedure:

1) remove the old acrylic from the frame - run the utility knife along the edge of the old acrylic - cut deep all the way around – turn it over and work from the backside with a blade horizontally under the rubber seal - it comes out fairly easily
2) clean the edge of the old acrylic - it is template for cutting out the new piece - you don't want the bearing of the router bit going over bumps of old sealant.    This can be done just with a sharp blade - no need for chemicals.
3) clean the old frame - this is time consuming,  lots of scraping – use alcohol – also for the frame.
3a) replace the rubber seal if required
4) stick the old lens to the new material with double sided tape - leave the protective cover on the new acrylic
5) rough cut with a jigsaw or bandsaw about 1/8" to 1/4" oversize
6) trim flush with the router – leave the edge rough for the sealant to grab on to
7) drill holes through using the old lens as a template - the big holes are through holes - don't drill the small holes all the way through!  Set a depth stop on the drill press or mark your bit with tape to the correct depth
lay the new acrylic into the frame and center it
9) on the underside mark the edge of the rubber seal with a pencil, score lightly with a knife and peal back the paper all around the edge – to expose acrylic where the seal will be
10) mask the frame and the top edges trimming back excess precisely with a sharp knife
11) remove the acrylic from the frame and lay in a heavy bead of sealant in the bottom of the frame
12) put the acrylic back in the frame and fill the gap with sealant
13) smooth to a nice finish and remove the mask
14) let it cure, remove the protective paper on the underside and trim excess sealant
15) reattach the handles and install

Having trouble posting photos - I'll do them separately

[waterdog]

Some photos...

[waterdog]

And the rest...

[Craig Illman]

Impressive job!  I used the expensive GE stuff when I replaced the lens in my Bomar salon hatch. It's a structural sealant. I used the balance of the first tube in the grooves of the companionway steps when I refinished them last winter. I ordered another tube through Amazon when I resealed my fixed portlights last summer. I feel it was worth the $15-20.

One of these days I'll need to tackle my Lewmar hatch as well. It's probably going to need hinges as well as a lens.

Craig

[waterdog]

Hmmm.   I think Lewmar uses two sealants.  Silicone for the top gap and something else in the bottom bedding.   This bedding stuff was gooey after 20 years, sticks to absolutely everything, really hard to clean.   I couldn't imagine putting it in stair treads.  Maybe we are talking about different things?

[Stu Jackson]

The "fill-the-slits concept was published in the November 1998 part of the Mainsheet, not necessarily "captured" in the Tech Notes "section" so here it is for those of you with older boats that are still catchin' dirt

It was one of the first things we did when we bought our boat and has stood the test of time, almost ten years later is still intact.

This page shows two different projects, one for the spash guard, the second is the steps project.  Many have done differing versions of the spash guard.  I think this one is too big, and we have never done one.  Easy for me to say, because I sit elsewhere when the dishes are being done...

[Craig Illman]

Steve - I still had a partial tube in my small basement shop. It's called UltraGlaze. Maybe Lewmar uses Butyl rubber for the bottom? The UltraGlaze isn't sticky after it dries, but quite pliable. It's actually shiney when cured.

Craig

[waterdog]

Oh well in that case, I would use the GE Ultraglaze!   Hmm, perhaps on my next hatch...

[foursailing]

Steve - Where did you get the 1/4 inch acrylic?

Thanks,

Bill

[waterdog]

Bill:

I got the acrylic from a local plastics supplier.  www.ippnet.com   For the hatch, it was 1/2" material and there's no reason you couldn't even go a little thicker.  The nice part was I was able to get a grey bronze tint which very closely matches fixed windows.   Now everything just looks black from the outside whereas before I had grey fixed windows, a blue tint in the opening ports, and a green tint in the foreward hatch.   Now it's all the same.     

[foursailing]

Thanks Steve!!