Broken Hatch Lens

[ggray]

Has anyone had a hatch lens break, or know of someone who has had it happen? If so, was it something out of the ordinary such as dropping an anvil on it? Or was it something that could easily happen such as someone stepping on it, or even a wave impact?

I've seen transparent hatches with crazing all over, and while my white hatches don't exhibit this, I've been told it can happen to these, but you don't see it.

My hatches are 22 years old, and I'd like to have an idea if this is something to worry about.

[GordMay]

Hatch lenses don't usually break [from someone stepping on it, or a wave impact], unless struck by a heavy, hard, sharp edged object.

Plexiglass (UV stabilized; cell cast acrylic) is what hatchmakers Bomar and Lewmar [et al] use for standard hatch lenses.

They do not recommend the use of any type polycarbonate in deck hatches.
During extensive testing, of several brands of polycarbonate. it has been determined that, although polycarbonate is stronger than acrylic of the same thickness when installed, It degrades and yellows at such a rapid rate, that its useful service life could be half that of acrylic.
Due to its high impact strength, polycarbonate is very ductal. This flexibility makes the material extremely difficult to seal, in a hatch that was designed to accommodate the stiffer acrylic sheet. It also makes it prone to “popping out” of it’s frame, when hit with (say) a wall of water, or a crew, hitting it.
Scratching or abrasion is a significant problem with polycarbonate. The material, in its standard grade, has a much softer surface than acrylic. The slightest rub will cause a visible scratch that cannot be removed. Several of the major manufacturers of polycarbonate have introduced scratch resistant-ultra violet stable material to address these issues. Even with these costly, and hard to find upgrades, the special surface coatings tend to de-laminate, due to the exposure to the elements. If you can't count on it to seal why use it?
Polycarbonate also cost more than Acrylic of the same thickness. Add in the up-charge for the scratch resistant-ultra violet material and the material cost could easily be double that of Acrylic.

Acrylic vs. Polycarbonate ➥ https://hatchmasters.com/acrylic-vs-polycarbonate/

Hatch repair:
Hatchmasters ➥ https://hatchmasters.com/
Select Plastics ➥ https://selectplastics.com/mrine-hatch-repair/

[noelex 77]

Acrylic does become brittle with age and UV. I have seen examples that have broken with little force (usually when removing the hatch lens). We even had one spontaneous crack all the way through with no external force (other than that exerted by the hatch handles). The scary part was although the lens was old and had some crazing it was otherwise not in bad condition.

[Rumrace]

The lens can break. I think I’ve seen 2 in 50 years. One was broken in covered slips by the crane hook. They finally fired the kid.
Most manufacturer will rebuild their own ports and hatches.
I had a guest have a panic attack and pushed the glass out of the frame. The piston kept the lens from sliding off. The window would not seal again so I removed it and sent it to the maker then in Ohio. They replaced the trim and sealing gasket sent it back New at a very reasonable cost. The Sea Ray Dealer in Indiana told me about the OEM supplier.

[ggray]

Thanks for the replies!

This must not be a common occurrence.

[chris mac]

Ours are almost 30 years old, pretty crazed, but still sealed. This year in the Bahamas one cracked as I stepped on it. (I have stepped on them many times prior with no problems) The seal around is still good but the crack leaks, of course
Luckily I have a contact that works with acrylic and has a c and c machine. So I plan to have replacements made this summer

[team karst]

I’ve rebuilt 6 of my Lewmar hatch pieces, prompted more for the seals, but nice to get the cosmetics fixed as well. The gaskets shrink over time and harden. Splitting the two piece aluminum extrusion is a trick.

[gonesail]

you say they are white .. are they the cast aluminum bowmars? if so probably worth replacing the acrylic.

[Cheechako]

Spinnaker pole dropped on hatch and it breaks. Seen this a couple of times racing.

[MWGDVC]

My forwardmost hatch had a broken lens (Bomar 100 series) when I purchased the boat. After careful consideration, since most people add covers to their hatches to reduce heat, I had non-skid white Starboard machined to the lens dimensions. Now I can walk on the closed hatch with confidence. On sunny days the Starboard gives off a bit of a glow. Light really isn't a problem on our boat anyway, 16 portlights, and 4 opening hatches. I am very pleased with the end result.

[donradcliffe]

Originally Posted by GordMay

Hatch lenses don't usually break [from someone stepping on it, or a wave impact], unless struck by a heavy, hard, sharp edged object.

Plexiglass (UV stabilized; cell cast acrylic) is what hatchmakers Bomar and Lewmar [et al] use for standard hatch lenses.

They do not recommend the use of any type polycarbonate in deck hatches.
During extensive testing, of several brands of polycarbonate. it has been determined that, although polycarbonate is stronger than acrylic of the same thickness when installed, It degrades and yellows at such a rapid rate, that its useful service life could be half that of acrylic.
Due to its high impact strength, polycarbonate is very ductal. This flexibility makes the material extremely difficult to seal, in a hatch that was designed to accommodate the stiffer acrylic sheet. It also makes it prone to “popping out” of it’s frame, when hit with (say) a wall of water, or a crew, hitting it.
Scratching or abrasion is a significant problem with polycarbonate. The material, in its standard grade, has a much softer surface than acrylic. The slightest rub will cause a visible scratch that cannot be removed. Several of the major manufacturers of polycarbonate have introduced scratch resistant-ultra violet stable material to address these issues. Even with these costly, and hard to find upgrades, the special surface coatings tend to de-laminate, due to the exposure to the elements. If you can't count on it to seal why use it?
Polycarbonate also cost more than Acrylic of the same thickness. Add in the up-charge for the scratch resistant-ultra violet material and the material cost could easily be double that of Acrylic.

Acrylic vs. Polycarbonate ➥ https://hatchmasters.com/acrylic-vs-polycarbonate/

Hatch repair:
Hatchmasters ➥ https://hatchmasters.com/
Select Plastics ➥ https://selectplastics.com/mrine-hatch-repair/

I don't agree with hatchmasters. The polycarbonate lenses are used on race boats because they can be thinner and lighter and far more impact resistant. If they are thinner they bend easier. Here is another comparison

https://www.piedmontplastics.com/blo...he-differences

[donradcliffe]

If acrylic hatch lenses have been in the sun for 22 years, its probably about time to replace them. If you DIY its time consuming but not expensive.

I my experience, some hatches craze and some don't, even on the same boat, and even on areas on the same hatch. I have traced the crazing to use of cleaners containing petroleum distillates. If you have an old hatch lens that is not crazed, try brushing a pattern with paint thinner on one part and leaving it in the sun for a year.

I agree that the most abused hatches are on the foredeck of race boats. Not only do they get hit with the spinnaker pole, they get slammed open and shut and stepped on when they are open. Sometimes they even the score when the foredeck crews fall through them when open.

[ggray]

Originally Posted by gonesail

you say they are white .. are they the cast aluminum bowmars? if so probably worth replacing the acrylic.

They are Lewmar hatches with white lenses.

Thanks for all the replies!

Varying opinions, but at least I'm not guessing in the dark.

[team karst]

My lewmars came light green, and ive been using smoke gray as replacements. Looks a wee more modern, IMO. Are these white lens opaque? Were they white when new?

[noelex 77]

Originally Posted by donradcliffe

I don't agree with hatchmasters. The polycarbonate lenses are used on race boats because they can be thinner and lighter and far more impact resistant. If they are thinner they bend easier.

Polycarbonate is stronger than acrylic, but it flexes significantly when a large force is exerted.

For marine hatches this flexing causes practical difficulties securing the lens. Of course if the hatch lens pops out of the frame or flexes enough to break the sealant the watertight integrity is lost. Polycarbonate lenses therefore need to made thicker than would required by the strength alone so that the lens will avoid these issues. The net result is a polycarbonate hatch lens has to be as thick if not thicker than an acrylic or glass lens in most marine installations.

As polycarbonate is lighter there is still a net weight saving. This weight saving appeals to top racing boats, but for most yachts acrylic is the best choice, as it has greater scratch resistance. This is why almost all hatch manufacturers use acrylic rather than polycarbonate.

If you want the ultimate in durability, glass is the best choice, but only a few top end manufacturers use this material.