SailNet Community banner

1 - 12 of 12 Posts

·
Schooner Captain
Joined
·
2,199 Posts
Discussion Starter #1
My hatches need replacement material.
I believe they are cast acrylic now.
Would shatterproof glass be strong enough, impact resistant enough?
Its a size 70, so the pane would be large.
I would also coat it with a layer of the safety film that keeps it all in tact in case of breakage.

Windshields are fairly strong, and I have had some large items hit the window and only spider it.
Thoughts? suggestions?

I am having a hard time finding replacement cast acrylic, and lexan is out due to lack of stiffness.

There must be some reason hatch manufactures don't use glass from the factory?
 

·
Registered
Joined
·
830 Posts
What (actual) size is a #70?

Even "bullet proof" glasscan be broken/gotten thru. Could be cost/return factor against?

Try AIN Plastics; now a different name; but should come upwith a search. They have all sorts of acrylic and Lexan.. I opted for lexan on the fwd hatch,as it's smaller and has support/s. Could you provide support without compromising strenth of surround?

HTH,
Paul
 

·
Registered
Joined
·
1,106 Posts
Good question Union! I've been thinkng the same thing myself- surely there must be a glass product available today that is srong enough for hatches and ports. I recall seeing a vídeo some time ago about a Florida inventor that came up with a special glass that could withstand hurricane-driven debris hitting windows. I wonder if it ever went to market? FWIW, my hard dodger windscreen panels are made of tempered glass. They're as new and clear as the day they were put in.
 

·
Registered
Joined
·
1,446 Posts
If you want to go with glass look for impact resistant glass used in domestic windows. While the glass will break given a strong enough force (the test is a 2 X 4 shot out of a cannon at 60 mph) the integrity of the panel is not breached, due to an inner layer of plastic bonded to the panes of glass.
By the way, the windows on my Pearson 28 are made of "safety" glass, but have not had an impact event.
John
 

·
Registered
Joined
·
1,106 Posts
CCRiders, I think that's the vídeo I saw- they shot a 2x4 out of a canon and the glass deformed and crazed, but remained intact. You woudn't happen to know the comercial (market) name of this glass, would you?
 

·
Schooner Captain
Joined
·
2,199 Posts
Discussion Starter #6 (Edited)
CCRiders, I think that's the vídeo I saw- they shot a 2x4 out of a canon and the glass deformed and crazed, but remained intact. You woudn't happen to know the comercial (market) name of this glass, would you?
This may be the safety film they sell.

3M Scotchshield Automotive Security Films - Clear and tinted Security films for cars, trucks - 3M Scotchshield
http://solutions.3m.com/wps/portal/3M/en_US/Window_Film/Solutions/Support/FLhurricanes/
The windows on my hard dodger are glass as well.

My 70 hatch is about 24x24, no center supports.
 

·
Registered
Joined
·
1,073 Posts
Approach a glass company with an accurate drawing of the light needed. Ask for laminated glass with temped outboard, heat strengthened inboard with .090 SGP interlayer. I'm not sure how thick your hatch could accommodate, but the thicker the better. 3/8" to 9/16". The thing about hurricane resistant glass isn't that it doesn't break, but when it breaks, it stays in the frame for the rest of the storm. The tempered glass can be HIT with a hammer with no effect. But tick the edge with a wrench and you can loose the whole thing. So, tempered outer for strength, heat strengthened inner for cohesion, SGP interlayer to bind it all together. You'll probably pay around $40/SF for it.We have several Dade County approved hurricane skylight families.
 

·
Master Mariner
Joined
·
8,973 Posts
We had to replace the acrylic on a hatch that the dink rests on, on the foredeck, when we are underway. We went from 3/8ths inch acrylic to 1/2 inch lexan and I have absolutely no fear that it will ever break again. It is slightly too thick to fit in the frame, but we had it nicely beveled and it is not a tripping hazard at all.
I sure don't see 1/2 inch lexan being very flexible and I'm pretty sure it's bullet proof; we used some as storm boards on a big motorsailor some years back. If your hatches do not have ribs across the area where the glass goes, they are not "offshore" hatches and need to be replaced. Hatch 2 is an "offshore" hatch, hatch 1 is not.
The only glass product I can remember seeing on a small ocean going craft, was the glass with the chicken wire in it, in a skylight on an old gaffer I owned. It did survive 3 capsizes in a bit of a blow in the SoPac, amazingly enough, even when hit by pieces of the main boom as it shattered during one roll.
 

Attachments

·
Registered
Joined
·
4,917 Posts
I would stay with acrylic. Contact these guys. They know more above rebuilding hatches than just about anyone else. I'm sure they can sell you the right materials even if you don't want to have them do the work.

Home
 

·
Registered
Joined
·
7,857 Posts
If your hatches do not have ribs across the area where the glass goes, they are not "offshore" hatches and need to be replaced. Hatch 2 is an "offshore" hatch, hatch 1 is not.
Bomar is the only company I know of that uses cross bars on their hatches. They are there to keep the Lexan from flexing and breaking the seal - they don't use 1/2" Lexan. Every other hatch manufacturer I know of uses acrylic of a suitable thickness and many are "offshore capable" hatches. Lewmar Ocean series for example.
 

·
Registered
Joined
·
3,184 Posts
My understanding is that Lexan is very strong, no worries there, but it does not stand up to UV as well as acrylic. That's the reason acrylic is normally used, that and cost. A thick sheet of Lexan gets really expensive.

Car windshields etc. are laminated - they have an inner plastic layer to hold it together.

In my humble opinion, you really need to source some acrylic.
 

·
██▓▓▒▒░&
Joined
·
13,645 Posts
"I recall seeing a vídeo some time ago about a Florida inventor that came up with a special glass that could withstand hurricane-driven debris hitting windows. I wonder if it ever went to market?"
it is generally called 'hurricane glass" and it is just a sandwich of two thin glass panels(for scratch resistance) two layers of a plastic adhesive film, and one center layer of lexan or plexiglass, which is the actual structural part.

A car windshield is very similar, two layers of safety glass which shatters on impact and turns into thousands of small sharp pebbles instead of the large "daggers" that plain glass would become.

No magic to either one, any real commercial glazier or plastics fabricator can make up sandwiched layers like that. Sit down and hold your breath before you call them to ask for a price.

Scotchshield is a thin film ( about 2 mils?) of polycarbonate, like lexan, with a water based adhesive. It goes on like any window film but it is designed to remain bonded with glass, so that if a bomb goes off in front of your office, the big windows crumple instead of turning into a thousand sharp bullets. Literally.

Lexan MR10 (Mar Resistant) is the commercial Lexan product that comes with a similar anti-scratch and anti-UV film already bonded onto one side. It is used in railway car windows, which are required to be bullet-resistant. Costs more than plain Lexan but resists scratching more, and the film can be removed with heat and ammonia fumes and then replaced.

There's all sorts of good stuff for the asking and you could of course even have an inch-thick tempered safety glass panel made up. But tempering glass requires special ovens after it has been cut, and there are very few places that would do that.

Boatbuilders use plexi and polycarbonate because they are the simplest cheapest way to get a reasonable job done. If you've got deep pockets and want something better...by all means.
 
1 - 12 of 12 Posts
Top