The goop could be SIKAFLEX which sticks like the proverbial to the blanket, if it is fresh. The company is notorious for not accepting back product that has exceeded it's shelf life from their retailers so be wary of the use by date.

It comes in white or black.

If one window has come unstuck, the rest are probably about to.

Were I you which I am not but if I was, I would pull the lot off and fit new perspex or lexan (up to your budget) with silicon as a sealant and the windows attached by mechanical means such as 3/16" or 4mm bolts.

The silicon I would use is plumber's roofing sealant. If it can handle the sun on the roofs of Australian houses for 10 or 20 years or more, I am sure it will handle at least 5 years on your boat.

You can buy it anywhere for $5 to $8 a cartridge. Sikaflex or it's Australian made equivalent will cost you $20+ per cartridge and what you don't use will not keep.

It is the same old story mate. Put the word "Marine" in front of the product name or type and you will be ripped off usually. Hope this helps, Cheers Cisco.

Wow! Good old Sikaflex? I imagined it'd be some exotic super strong, hard to get, impossible to apply boatbuilder-only stuff. Sika is my favourite sealant and adhesive. No kidding... I've used it everywhere on my previous two boats. Have never used the primer but then I've never had it come unstuck from GRP before. And yes, it's expensive but easy to find here where I live from Bunnings, Whatsitworth and Biased.

Thanks, guys. If that's all it's likely to be then I'll give it a shot. For my own comfort, after it's cured a week or so I'll be sure to give the windows a good KICK. I figure if they can't take a kick, they probably won't take green water.

Maxm if you go down the Sika road be sure to use the primer! I didnt and i paid the penalty, lots and lots of hard work to redo the job a second and proper time