Replacing/repairing portholes/windows

As I found out that the windows/portholes were made of glass and cracked when I tried to tighten the bolts to make the seal work better, it means that now I need to replace them! 

When I removed one of them I found the the 'glue' or whatever had been used was horrid. Either it had degraded in the UV light or was never supposed to set but be a sticky bitumen type seal. 

Whatever, it left a sticky residue on the hull and the glass and was a bit of a pain to remove.

Though maybe not had it set into a hard band of black glue!

Having removed as much as possible with a knife, Sheila, who was helping me for the day, used pure alcohol on a cloth to wipe away what was left.

It worked, but was quite a task.

I'm replacing the glass with 5mm Acrylic sheet, so I used the old glass window as a template.

This also helped to drill the fixing holes in position.

Then used the jig saw to cut the shape.

I used the wood to run the jigsaw down the sides and then by hand cut the semi-circular ends.

I later found that was easier to do with the marked line on the bottom and looking through the acrylic sheet at the marked line!

 I then put the new window against the opening, locating with a couple of bolts, and from the inside with a craft night carefully cut around so that I could remove the edge of the protection film.

Then put Sikaflex UV resistant glue around the edge and mounted in place. Any Sikaflex that squished out, came off when I removed the protection film.