plastic window installation

We replaced the windows on our Nicol Vagabond MK2 using the method outlined on this website: http://www.thecoastalpassage.com/windows.html It works for either acrylic or lexan/polycarbonate. I came up with a couple of ideas to make it easier when cutting openings for the windows, cutting out the windows, painting the border and putting the tape on. Basically a pattern is made for the window in the form of a ring. The outer dimension is used as a window pattern and for marking the cabin sides for tape and window position. The inner dimension is used for marking the window inner border/overlap for painting and as a pattern for the window cutouts in new construction.
The website mentioned the stress of getting things placed just right so we dry fitted the windows and used some of the 2 sided 3M mounting tape to temporarily mount support blocks of scrap wood to hold and position the windows. This made the actual mounting of the windows very easy. If the blocks are removed right away after the installation your paint system shouldn't be harmed. The site mentioned putting some of the adhesive caulking on before mounting but we found it far easier to do after the window was in place. The Dow Corning adhesive suggested does let you add a second/fairing layer if you felt you need a bit more here and there and is easily trimmed after curing.
I suggest using wider tape instead of 2 narrow widths, in the States various widths are available by order. Remember to leave a good depth for the outside caulking and a shallower depth for the inside of the window. If you don't caulk the inside seam condensation can migrate into the tape system. The corner radius have to be made up of short tape lengths cut to fit but it is very easy to get the hang of. This method of window mounting can work on most kinds of construction including metal, glass/fiber composite and wood composite.