Hatches

I have downloaded some catalogs to look at what some of the accessories are. Looking at the hatches, it seems they all use glass.

Is there any reason why one cannot use perspex (Acrylic) for hatches' glass ?

Perspex is supposed to be 10 x stronger than glass...

And why are they all smoked glass ? To keep vision out and not in ?

 

Sun kills perspex.. worse when flat.. crazing etc.. (prolly depends on grade/type as well) I think lexcen (?) is the go, if I remember rightly.. oh I forget... but there is some good non glass stuff.

 

Perspex is perfect for using in the sun. UV resistant for many many years.

 

Fanie...

Mate, I have seen way to many hatches & boat windows that you can't see through for the crazing. Yes they use it but because its cheap and lasts long enough... if you want durable, long term, its not the go, at least not in a place that gets decent sun light. That is unless they have improved it in the last decade or so. They use glass for a reason.....

I think its called lexan the alternate, it is a polycarbonate from memory, tough as, but expensive. Some one correct me... memory failing!

Here we go...

http://www.gcip.co.uk/EP/lexan_polycarbonate_sheet.htm

 

Hi Meanz, we used to use polycarbonate in our lights... they crack up very quickly. Perspex doesn't have a UV issue, and it's not cheap either. One of our house windows is perspex, nothing wrong with it agter 7 years. You just cannot scrub it with abrasive cleaners.

If there is no specific reason why it won't work on boats then it would work.

I'm considering perspex because I can cut my own hatches on the laser cutter.

 

why not wood ?,,and open ,,when you wish to see light???

 

why not wood ?,,and open ,,when you wish to see light???

 

I will make them to open too if you want fresh air. If the weather is less nice you can keep them close but still see outside and have light.

 

Thats a house window, its relatively protected, I'm sure that they also have better performance in most parts of Europe than we see here, even here boat windows survive better than boat hatches because of there orientation. I have seen places where one side of the boat gives up but the other is fine simply because of the boats mooring orientation. Fanie I sold used boats for over a decade... I have sailed and seen many hundreds of yachts in that time... please don't tell me what I know to be true is not correct, Perspex crazies in the sun... yet still we used it when we where building boats (having them built more accurately)... thicker the better the resistance, the longer you got.

Now that may have changed recently, but not to my knowledge, so unless you know that for a fact? (No doubt there are differing grades commercially available)

Lexan was considered the better hatch alternate for strength reasons, but its more expensive, anyway eventually the sun does get it too... glass is probably the only long term solution if crazing is the concern but its not as strong. Hardcore blue water types go with Lexan for the outright strength, commercial suppliers probably go with toughened glass for the best strength, cost, durability combo... these people are not stupid and they do know about the alternates.

 

I have seen some good ones with very solid glass deck prisms near and or in it to get light below. LL has a point, a great big sheet of clear stuff is not the only way to go.

Cheers
MBz

 

Your choices are acrylic (weak, cheap, depolymerizes and crazes quickly), polycarbonate (stronger then acrylic, depending of formulation, but still depolymerizes with UV), and of course glass which doesn't craze, yellow or break down in UV and can be had in laminated form.

 

I can step on wood,,,,but not these thin piecse of glass

 

The other thing is that the right sort of glass is probably more affordable if you are in production as apposed to doing a one off job. I suppose the alternates are often attractive because they can be worked on a one off basis (never tried to work Lexan but I think thats so?). That is where I have seen most perspex used in hatches, one off jobs on timber boats... once they craze I'm very wary about standing on them, be prepared to replace it sooner rather than later if you do go that route... you might find yourself up to your bollocks in hatch and water

 

Actually, almost all ocean alloy hatches are glazed in Acrylic.......

Not that I am saying this is a good thing, we all know better, but that is the case.

 

Yeah I had not looked for a while, I took Fannies statement about glass at face value... The Lewmar ones with he handles through the light look to be Acrylic to me but I've not bought one or asked about it for a long while!

I went and looked...

They allow for replacement They must be using a better quality product because they do last better than any on the one off jobs I have seen. As always the devil is most probably in the detail of the type of acrylic you use.