Lexan VS Acrylic

[weephee]

I am replacing the smoked cover on my hatch. I don't know what material it is but I do have a piece of smoked acrylic available to me. Area is 20 inches x 20 inches with two parallel support pieces running 5 inches apart under it. Is it OK to use the acrylic or should I be looking for a piece of Lexan. Thanks

[sailingdog]

Most hatches use cast acrylic, not lexan, with the exception of a single line of Bomar hatches IIRC. What kind of port is it? How thick is the piece you have?

[JohnRPollard]

Our Bomar hatches are polycarbonate (Lexan). Most other hatches I've worked on were too.

Lexan is stronger but less UV resistant than acrylic. Acylic is often used for smaller portlights, whereas Lexan is preferred because of its strength for larger areas like hatches.

For a 20"x20" opening, I'd use Lexan/polycarbonate, not acrylic.

[sailingdog]

JRP—

I doubt that... Most hatches are cast acrylic because polycarbonate foreshortens when it flexes under impact, making it very unlikely to remain sealed. If you check with Lewmar, one of the larger hatch producers, all of their specs mention the thickness of the acrylic... not lexan or polycarbonate.

[PeterSailer]

I don't know about acrylic but Lexan is very easy to scratch...

[JohnRPollard]

SD,

Has that always been the case? I guess I've worked on a few hatches in the past, all of them older and in need of work due to UV degradation. I recall them being polycarbonate.

I also recall when researching a material to use for our portlight lens-replacements (in our previous boat), that acrylic was considered a good fit for portlights, but that polycarbonate was recommended for hatches or larger deadlights.

Maybe there has been a shift in newer hatches to acrylic, or is it that some of the "value" oriented designs use this less expensive material for the lens?

Here's one that is similar to ours, which uses polycarbonate:

BOMAR CAST ALUMINUM HATCH # 139L. 24 " X 24" BLACK

[sailingdog]

acrylic- more scratch and uv resistant

Lexan- more impact resistant

[sailingdog]

Originally Posted by JohnRPollard

SD,

Has that always been the case? I guess I've worked on a few hatches in the past, all of them older and in need of work due to UV degradation. I recall them being polycarbonate.

I also recall when researching a material to use for our portlight lens-replacements (in our previous boat), that acrylic was considered a good fit for portlights, but that polycarbonate was recommended for hatches or larger deadlights.

Maybe there has been a shift in newer hatches to acrylic, or is it that some of the "value" oriented designs use this less expensive material for the lens?

Here's one that is similar to ours, which uses polycarbonate:

BOMAR CAST ALUMINUM HATCH # 139L. 24 " X 24" BLACK

Note the reinforcing bars—they're to prevent the polycarbonate from flexing enough to break the seal. Yours are the one kind made with polycarbonate. All the others are acrylic.

[erps]

Which one bends with some heat? I've seen some do-it yourself projects using one of those materials. It looked easy to cut and easy to shape but I can never remember which one.

[sailingdog]

Both will bend with heat. Both are fairly easy to cut and shape.

Originally Posted by erps

Which one bends with some heat? I've seen some do-it yourself projects using one of those materials. It looked easy to cut and easy to shape but I can never remember which one.