New hatch - what material?

Colvic Watson

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I want to replace the aft hatches with a smoke-grey or black plastic. The design of the aft hatches means that a standard hatch with a frame can't be fitted as the hatches incorporate an opening door below. Currently they have very heavy fibreglass 'lids' on a hinge. I'm thinking of using a sheet of plastic, cut to size and fitted with a hinge. Trouble is it must be strong enough to take the occasional person standing on it. The width is the usual hatch size (?50cm) so the span isn't huge. What material would you recommend and what are the suppliers to try?

Thanks for your advice. Simon
 

tobble

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I have been thinking about a similar problem, in that I want to replace my GRP fore hatch with something that will elt a bit more light though. Rather than bin a perfectly good hatch, spend gawd knows how much on a hatch and spend days faffing to get it to fit, I reckon cutting a hole out the middle and just bolting a thick (8mm?) bit of perspex over the top... dunno if that helps at all!
 

boatmike

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Perspex is generally used for hatches because it is relatively hard, cheap and will take the load of a big pair of boots standing on it .
 

cliff

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[ QUOTE ]
Perspex is generally used for hatches because it is relatively hard, cheap and will take the load of a big pair of boots standing on it .

[/ QUOTE ]Cheap? I suppose it depends on what you define as cheap. Mind you, The Metal Center in Leith is flogging off 15mm thick panels (960 X 1170 approx) for £5.00 a sheet at the moment. - slightly "shop soiled". It is clear but tinted window film is cheap /forums/images/graemlins/grin.gif
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FullCircle

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Two choices really Simon:-

Acrylic or Perspex.

Perspex is harder and more resistant to scuffing underfoot, but has a poorer resistance to UV aging and therefore micro cracks develop over time, but we are talking 10 years UK (see lots 70s-80s boats in the marina). Also, structurally Perspex, being harder, is more susceptible to impact damage and will crack. Advantage is it is at least 1/2 the price of Acrylic, probably more.

Acrylic has a softer surface and will mark up over time if feet are regularly scuffing over it. This can be polished out with T Cut or similar. The UV properties are excellent and the material is very much more resistant to shock loads as it has a greater flexular modulus. Riot shields are made from it. Disadvanage is cost.

Both can be machined to shape with routers, and both will take a tapping for threading bolts or screws into it. The acrylic will bite on the bolt thread more.

Use of 10mm or 12mm will be OK. You should be able to pick up an offcut rather than a whole sheet.

EJ Alloys in Southend will cut the bit and make it for you, and they do a great job ( he makes historic plane parts too) but he is aware of the market rates for doing it. Ahem.

50cm x 50cm prob about 10-15 quid in Acrylic (no machining), which would be my choice.
 

boatbuilder

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Perspex is the reg trade name that ICI has for acrylic, I suspect that you are confusing it with polycarbonate wich has the trade names of Makrolon or Lexan.
Polycarbonate is all most unbreakable but is soft surface and scratches easy.
 
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