What material should I use to replace my cracked windows? Any recommendation where to buy?
Also was wandering if the cracking is due to normal ageing of the plexiglass or because of stress when walking on the roof (will it crack again in two weeks)?

If you can get it out without breaking it too badly, remove it and take it to Plastix in Brookvale or Banksia. They'll cut you a new one out of Polycarbonate or Acrylic in either clear or a tint. It's not that expensive. Hardest job is sealing it against the weather when you put in back in.

If you can't get it out and have it out for a few days, get a big bit of paper and carefully trace a template and they can work from that. You'll need to know how thick you want the acrylic though. Mine is 10mm. But you can get it in a variety of thicknesses.

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MichaelR said..
If you can get it out without breaking it too badly, remove it and take it to Plastix in Brookvale or Banksia. They'll cut you a new one out of Polycarbonate or Acrylic in either clear or a tint. It's not that expensive. Hardest job is sealing it against the weather when you put in back in.

If you can't get it out and have it out for a few days, get a big bit of paper and carefully trace a template and they can work from that. You'll need to know how thick you want the acrylic though. Mine is 10mm. But you can get it in a variety of thicknesses.

Thks MichaelR, will do that. What material did you choose?

I'm about to replace my fixed ports...I'm going for tinted polycarbonate.

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samsturdy said..
I'm about to replace my fixed ports...I'm going for tinted polycarbonate.

And I'm in the same boat too, but going for acrylic - scratches & UV coloration
www.cutplasticsheeting.co.uk/blog/clear-acrylic-2/acrylic-vs-polycarbonate/

...am I alone here, when you start the show and shine game on boats, you just don't know when you stop!

PS - perhaps its that 'what have you done on your boat' thread hmm Southace

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cazou34 said..

MichaelR said..
If you can get it out without breaking it too badly, remove it and take it to Plastix in Brookvale or Banksia. They'll cut you a new one out of Polycarbonate or Acrylic in either clear or a tint. It's not that expensive. Hardest job is sealing it against the weather when you put in back in.

If you can't get it out and have it out for a few days, get a big bit of paper and carefully trace a template and they can work from that. You'll need to know how thick you want the acrylic though. Mine is 10mm. But you can get it in a variety of thicknesses.

Thks MichaelR, will do that. What material did you choose?

I haven't chosen it yet. I was recommended a mid tone grey acrylic. The thicker the better for security, and in case you get hit hard by a wave. One of the lads on tophatyachts.com did it with his Mark III Top Hat and used acrylic. Greg said getting the acrylic cut was easy. The re-fitting was the tricky part, there are so many methods from Windscreen adhesive to drilling and screwing and sealing with sika or silicone. I like the idea of windscreen sealant, but it's very messy.
I use acrylic most days in my sign printing trade. It's got a lot of uses from laser routed lettering to light box panels and plenty of other uses. Cutting a window panel for you should be a doddle for them.

The likes of fibre glass industries have sheets of acrylic and polycarbonate, and the handle on the appropriate sealant.
either is easy to cut with a sharp jigsaw or sharp handsaw, edges can be burnished with sand paper or sharp block plane, it's no more difficult than working with plywood. You will proably be suprised at how much cheaper it is to buy the whole sheet.
acrylic = less bendy more cracky
polycarbonate = more bendy easy scratchy.

ps. you have to get the right sealant / primer or it will leak in a year or so, don't ask me how I know.

the coastal passage online magazine, in their technical section has a good guide to fit new portholes.
i followed their guide 6 or 7 years ago and have had no leaks or problems since

I got a quote today for 2x cut to shape 1660 x 180 mm ; 6mm thickness windows (see my first post for pic)
acrylic :260$
polycarb: 280$
I'm on a low budget and find that quite expensive for just two pieces of plastic and 10min of laser cutting.
Should I just buy the sheets and cut them myself ? Is that easy enough to do with a jigsaw?

I would certainly, and have done it. Mine were on the outside, so more evident of any snafu's. Took window out and used it as the template, it was actually quite fun!
I needed a normal saw for the long straight cuts, and jigsaw for rounded edges. I tried the jigsaw on the long cuts, but it didn't work as well as the saw. I must admit I bought more so I had enough scrap to test my cutting skills first.

Polycarbonate is tough, but scratches easy and within a few years yellows significantly. Cast (as opposed to extruded) acrylic is the best bet, IMHO, in all but the most extreme applications.

If you want to cut out from your own sheets, and have a router, you can use a pattern router bit to copy the old shape to the new material.

Polycarbonate is tough, but scratches easy and within a few years yellows significantly. Cast (as opposed to extruded) acrylic is the best bet, IMHO, in all but the most extreme applications.

If you want to cut out from your own sheets, and have a router, you can use a pattern router bit to copy the old shape to the new material.

thks I took some acrylic.
1/3 of the price without the cutting