Window material Bowitco 400

[gljnr1983]

I am going to be replacing the windows in my Bowitco 400,at present it has perspex held in with the a jeeting style rubber.
I would like to do the new windows oversized with countersunk stainless screws and sealant gasket so can anyone recomend a material that is less likely to crack at the screw holes and a sealant for the gasket please?

 

[Tranona]

Acrylic (perspex) or polycarbonate are fine for this application. if you are not confident enough to drill the holes (not difficult) then get your supplier to cut to size, finish the edges and drill the holes. a local signmaker is probably the best place to go, but there are plenty of on line suppliers.

 

[macd]

The problem with countersunk holes in acrylic is that if the fastener is a snug fit, it allows nothing for the differential expansion which is inevitable with most substrates. The bore of the holes needs to be slightly oversized and the fastener not taken fully home. 'Cones' of butyl tape under the head of the fastener will allow a degree of expansion whilst still maintaining a seal. (We have two very large acrylic windows with just this treatment.)

Butyl is also excellent for sealing windows (and many other things), although the result, if visible, can be less neat than proprietary foam tape intended for use with acrylic. You might also check out Arbomast BR, a broadly similar material except that it comes in a tube: http://www.arbo.co.uk/arbo-sealants/arbomast-br/

It's possible to buy countersink cutters specifically for acrylic sheet. eBay/Amazon will have them. There's plenty of good advice on-line about cutting acrylic. The key is not to overheat the material, which can leave it prone to stress fractures.

 

[gljnr1983]

Thanks for the replys guys, would flat head screws be better than countersunk,obviously not as nice but the new stuff will be on a slight bend and i wont beable to avoid a snug fit in some of the countersunk holes.

 

[VicS]

Thanks for the replys guys, would flat head screws be better than countersunk,obviously not as nice but the new stuff will be on a slight bend and i wont beable to avoid a snug fit in some of the countersunk holes.

"Pan head " are what you want. You will still be able to choose between slotted, Posidriv or socket headed.

 

[Aja]

Acrylic (perspex) or polycarbonate are fine for this application. if you are not confident enough to drill the holes (not difficult) then get your supplier to cut to size, finish the edges and drill the holes. a local signmaker is probably the best place to go, but there are plenty of on line suppliers.

I wouldn't recommend polycarbonate for Windows on a boat. Softer surface means it is easier to scratch and unless you can afford to fit "Lexan" which has a good UV shield they will go opaque from cleaners and UV very quickly.

Edit :Additionally, I would go with interscrews and a butyl tape such as Scapa tape. Good range of interscrews available from Baseline Marine.
Donald

 

[Tranona]

Have used both Lexan and unbranded polycarbonate for getting on for 30 years for windows (2 sets on one boat) without any issues. Feel better with the extra strength and impact resistance it offers.