Moonlight / BSI hatches - "thin" acrylic ?

[vacendak]

As Gideon adviced, have thoroughly studied Moonlight production line
(for installation in new 45" sailboat)

Found out they apply rather thin acrylic - e.g. 8 mm for 500x500, 10 mm for 620x620 etc.

any experience - are such surfaces "walkable" ?

All other companies apply at least one "size" (2-3) mm thicker glass.

[vacendak]

after Extended Internet Browsing, here:

Lexan thickness for deck hatch - SailNet Community

seems that BSI Moonlights really have "undersized" glazing

[CanQua]

Just curious if you were planning on replacing yours, and if there is enough room in the bedding area to do that, or if you'd have to modify the area to keep some spacing between it and the inner and outer frame?

If using acrylic I'd recommend thicker, no doubt. The advantage you've got there, is uv and scratch resistance over Lexan. Would still love to see some stretched acrylic on a boat, If your acrylic breaks, it will break like plate glass(in large shards). And the edges are very important as it's the weak spot.

And as a quick note, standard acrylic is uv proof, but about 1/8th the strength of polycarb(lexan). Lexan (even tinted) will yellow over time. I've a long drawn out post on it somewhere that I tried to keep short, but failed so i'll not repeat it, just a link to it instead http://www.cruisersforum.com/forums/...07&postcount=9

Created a chart with some impact testing done in house you might be interested in

[Southern Star]

Vacendak, my boat came with Moonlight/BSI hatches and ports from the factory and I am in process of replacing all of them. For the larger hatches I went with Lewmar - vastly superior construction, in my opinion. The Moonlights have very flimsy latches (and they seem to require replacement of the o-rings on virtually an annual basis). Another advantage to the new Lewmars is that the lens is owner replaceable (the frames are made in two pieces and there is a neoprene gasket).

Having said that, there have been some incredibly low prices on new BSI hatches and portlights on Ebay recently.

Brad

[mikereed100]

Canqua,

That's an intersting study. It looks like the glass and acrylic did not fare very well. Was the glass tempered? What sort of device was used for testing?

Mike

[CanQua]

Falling Dart Impact (Gardner Impact) ASTM D4226 D5420 D5628

And no the glass was not tempered. Standard acrylic does not fare well. This is an impact with a blunted(round nose) dart from a specific height as you can see in the above link. From the shape and weight the impact force is calculated..

Normally a 2" sample is used and we had no need to get tempered glass as it wasn't a consideration at the time. You can also see the differences in how well the different types of polycarbonate faired. There is a big difference. I only wish I'd had the time to go the our other facility and test on the larger tester. This one, as you can see, was maxed out and couldn't break the new polycarbonate. I'll have to see if I can find any aged samples that I can use for destructive testing and then show how they degrade severely over time. Next time I get a week so spare I'll give that a go.