Replacing Lewmar Lenses

Dan_Y · Jan 30, 2018

Frank, what size is the port? Size 0 maybe?

agprice22 · Jan 30, 2018

Try Interstate Plastics or Eplastics on the internet. They both carry everything in acrylic sheets

thinwater · Jan 30, 2018

I don't understand the concern. The gasket fits to the hatch. If the material is thicker, it may stand 0.015 proud, but it will NOT affect sealing. By the way, this is much better than any recess, which will hold water on the lens.

I've used 1/4-inch in Lewmar ports, about 6 of them over the years. I actually like the lens just a tick high.

Scott T-Bird · Jan 31, 2018

You are talking about 1/64" difference so I hardly think it matters. Besides, I'd guess that the same machine makes 6mm and 1/4" thickness. It's just a difference in describing the same thing in metric vs imperial. Nobody is going to describe the thickness as 15/64" when it is nominally 1/4". We describe a 1-1/2" x 3-1/2" wood stud as a 2 x 4, right? Conversely, nobody would convert a 0.250" dimension into metric and call it 6.35 mm. It's just 6. Either way, they are the same thing. At least that's what I think. I suppose there may be metric machines and imperial machines that make acrylic in similar, but not exactly the same thickness, but I hardly think that 1/64" makes any material difference in this application. The tolerances are probably larger.

Scott T-Bird · Jan 31, 2018

I'm used to seeing glass panels described by a glass manufacturer in both metric and imperial dimension. The product is the same, regardless of which nominal dimension is most accurate.

thinwater · Jan 31, 2018

Frank P said:
Dan- yes, I have four size 0 and 2 larger (15-1/4 x 8-1/16). I can by these from hatchmasters but I am trying to save a few bucks as I am replacing all the acrylic except the large overhead portlight and the hull portlights

agprice - Thanks! Interstate looks like they have it...I don't know how a missed them

Thinwater - The hinges and cam locks are spaced for the 6mm thick lens. 1/4" are thicker so the added thickness will increase pressure on the gaskets. The added pressure may not be good over time and cause a problem. I don't know how sensitive the assembly tolerances are and these are 25 year old ports that still seal great....I just don't want to tweak something and have problems later

Thanks Again
Frank

Good point, but not a problem in my experience. My ports were 20 years old too, and them I lived with it for another 5-8, depending on the hatch. I have hatches that I reglazed and other I did not, and I can tell no difference at all. 15 thousandths is nothing compared to gasket give. You will feel a difference with the new gasket (I have replaced gaskets without reglazing).

Remember, I'm not guessing. This is something I have done many times, and it was years ago.

thinwater · Jan 31, 2018

thinwater said:
Good point, but not a problem in my experience. My ports were 20 years old too, and them I lived with it for another 5-8, depending on the hatch. I have hatches that I reglazed and other I did not, and I can tell no difference at all. 15 thousandths is nothing compared to gasket give. You will feel a difference with the new gasket (I have replaced gaskets without reglazing).

Remember, I'm not guessing. This is something I have done many times, and it was years ago on the PDQ I resently sold (the F-24 only has one hatch!).

Rick D · Jan 31, 2018

Frank P said:
Thanks for the input guys, remember these are opening ports, not hatches and they both dog down differently. "Hatches" dog fame to frame and these "opening ports" dog lens to frame.

Frank

Not to worry Frank. Mine are a tad thicker than stock; probably 14". Not a problem with the gaskets over nine years (March 2009).

dscribner · Jan 31, 2018

Frank P said:
I would like to make new lenses for my Lewmar opening ports. The original lenses are 6 mm (.236") thick. I cant find any readily available 6mm acrylic only 1/4". I am concerned that the ports will not clamp down and seal properly with the slightly (.014") thicker material. Has anyone made these from 1/4" and do you have any problems? These are pre 1997 style ports.

Thanks
Frank

Frank,

Nominally it's 1/4" but it's actually .236. I was a skylight designer for 18 years and worked fairly extensively with the stuff. Go to a local glass shop and ask for drop. Impact modified acrylic is best. It approaches polycarbonate (Lexan) for impact resistance but is more scratch resistant than poly. Cut it and shape it like wood. Sand the edges if they are to be exposed. Some suggest flame-polishing them. That works too and looks good if you're careful but really isn't required. If you;ll be fitting it into a frame, all is good. If you screw it to the cabin . . . don't. Use VHB tape and silicone sealant instead. Screws are old technology and not required except for the most extreme conditions. VHB and silicone is the same system holding the windows in skyscrapers. Ask me how I know. It's called a 4-sided structural joint. Been used for decades. Anyway, I have a glass of Fireball on ice, whispering sweet nothings into my ear. Wait, that's the dog breathing hard in my direction. At any rate, gotta go!

Keep us posted!

Don