New Portlight Lenses

[waterdog]

I came across a plastics vendor at the boatshow this year.   I picked up material for new portlight lenses and a forward hatch for the V-Berth.   Ours has suffered some serious crazing after 18 years in the California sun.  I went with smoke acrylic with a bronze tint.   

For the portlights, I had the vendor cut me 6 pieces 5.5" x 12.5" out of material that was 8.3mm.   The steps were as follows:

1) remove the an old lense, remove the dogs and adhere it to the new material with two sided tape.
2) rough cut 1/8" oversize on the bandsaw (or with a jigsaw)
3) route around with a flush trim bit
4) drill the holes
5) reassemble with a fresh set of o-rings

It's possible to machine 3 lenses in the time it takes to grill a couple of thick T-Bone steaks.   Turn the steaks before you drill the holes in the second piece.   If you like your steaks medium, go ahead and turn the steaks after the second is complete and do 4 before you take them off the grill.  Oh you can finish the edges with a quick whiff of the propane torch.  Don't put the lenses on the grill...

[Ken Juul]

If you have the tools it is an easy project.  Without the proper tools it can be a pita.  When I replaced mine I used Select Plastics, they are at most boat shows, at least on the east coast (www.selectplastics.com) Thought the price was reasonable, but I am sure more than your cost.  Kit came with new o rings for the toggles.

[Ron Hill]

Steve : I assume that you used the table router to smooth out the cuts from the band saw?   

[waterdog]

Actually I picked a bad picture showing the second pass cut.   The bandsaw just removes bulk material and there is no effort to get it close.   The router makes the cut.   The bearing on the router bit rides along the original lense as a template.    As you go around you create an exact copy.   It's easier to do this with the router mounted in a table, but it can be done just as well with a hand router - it just takes more work to clamp and unclamp the material on a workbench as you work your way around it.   Here's a picture of the cut for the forward hatch that probably shows it a little better...

[waterdog]

An update.  Material around 7mm will serve you better than the thicker 8mm+ material.   I ended up machining relief for the hinges and dogs of about 1mm.   The ports were just too difficult to close with the thicker gaskets.   They work and look great now, but it required another trip back and forth to the boat and the extra machining.