Hello all. I have been stuffing around with windows for a few days . As I mentioned my old original light magenta colour windows were crazed and nearly opaque. Replaced the front one a few years back and it is going to have a solar panel mounted behind it, real soon now!
The front starboard window just about fell out after I removed the screws so no wonder it was leaking , other one not much better. Main cabin windows were much better and the silicone seal had to be cut to release them but the starboard one still cracked during removal.
For anyone wanting to cut out your own windows I warn you it’s a pain in the bum and only for retired people in a lockdown. Do yourself a favour and get new ones cut/done professionally.
I started with one. I found using the old front window as a template not a good idea. After I marked out on the polycarbonate and cut it out the slight imperfections, and there were some, in the original were magnified and I had to do a fair bit of trimming and sanding. For my second one, main starboard, I got smarter , I made a new template that perfectly fit the inner flat section through which the window screws. You could use thin cardboard, but in my case I have a sheetload of old spinal X-Rays which is thin, easy to cut and trim and if you stuff it up just grab another few. Once I had this dead perfect I taped it to my poly and then traced gently around the edge with a medium black builders marker, the ubiquitous blue ones that bunny’s flog off in packets of four.
This gives you an exact 2mm or so extra which you can sand down to fit the fillet moulded into the window frame in the body . Once you get this fillet right the window should fit flat against the inner section you cut your template to and the bit you’ve sanded will give you the perfect seal, shape wise.
Cutting out. I used my multi purpose tool on the front window and while it worked I found it slow going when having to do long cuts. I also tried using a spiral saw I found almost new in the throw out to do the curves but did not find it that controllable. See now why the dude threw it out. In the end a thin kerf metal cutting disk on the angle grinder was the tool of choice. I cut chords around the outside of the curve and carefully sanded back to the line on my bench wheel sander. You need to be gentle and not let things get too hot when cutting and sanding otherwise the poly will just melt rather than cut.
Trimming and chamfering is absolutely done best with a bench style sanding wheel. Everything else was a trial....that failed
As per cruiserpetes job and as I did on my front window I used heatproof gloss black ( engine enamel in my case). This masks the glue, silicons or tape you use to glue/seal the poly
The most terrifying thing about doing this job is it is time consuming and one slip with a cutting instrument or scalpel when trimming your mask and you may scratch or stuff up your surface and it’s game over and start again on that window. Also mark windows and particularly sides carefully. At one point I was up late and tired and had cut and chamfered the poly and spent an hour masking the WRONG #$&$%** SIDE, you want the paint on the inside. Luckily I was too tired to hang it in the workshop and start spraying it. When I got up in the morning I realised what a dunce I’d been.
A masked several “louvre lines” for want of a better word into the window which I’d seen on a big yacht in Europe and I thought it added something to the boat.
All in all I am reasonably happy with the final outcome. They are sealed well and won’t leak. I opted to use new ss stainless screws as the holes were already in the hull and as I’m moored and , well so far so good, why mess with something that has worked for 40 years.