I recently replaced all the portlights (all were opening portlights). Four were Bomar aluminum and five were plastic Beckson, which were leaking and breaking. The Bomars had severely hazy lenses. I installed four 6 x 20 and five 5 x 12. The fifth 5 x 12 faces aft from the galley into the cockpit. All were 1 1/2" spigots, except for the 5 x 12 that faces the cockpit, which was a 2" spigot because that cabin side thickness was an inch thick.
There were a few issues with the cabin sides and a few issues with the portlights.
Interior cabinets:I built a cabinet for over the fridge area and its face frame caused interference with the wood spacer and the dog of the port light which is over the stove. I had to move that opening aft by 1.5". Check that area carefully if you have an upper cabinet over the fridge to ensure that any new port light will not conflict with the upper cabinet.
Cabin sides: In all cases, there was a gap between the cabin's fiberglass liner and the exterior cabin side. I filled the gaps with thickened epoxy (cabosil & milled fiber) and, where gaps were large, I epoxied in hardwood shims. Some gaps were barely 1/8" and the maximum was about a skinny 3/4", but most were about 1/2". This caused issues with the spigot lengths and machine screw lengths.
Wood Spacers:- NFM has only one thickness, ~5/8". With the variable cabin side thickness, this caused some variable spigot stick through on final installation. For example, the two vberth portlight spigots are flush with the trim ring, but most of the rest stick out about 1/2".
- The color and grain matching within each spacer is not very good. There is great variation. Fortunately, most of the spacer is covered up by the portlight's interior flange, so it's not noticeable.
Portlight issues:- Portlights do not come with screens or machine screws, you must pay extra for them. McMaster is about half the price of what NFM charges and you'll need to get extra of various length machine screws to accommodate your variable cabin side thickness. One can get matching M6 x 1mm truss head machine screws at McMaster Carr: https://www.mcmaster.com/screws/rounded-head-screws/system-of-measurement~metric/rounded-head-style~truss/thread-size~m6/
- The tapped holes in the trim ring were not tapped completely. I had to use a bottoming tap one each hole and gained nearly 3/16" more threads. Not sure if I needed the extra depth, but during final installation is not the time I wanted to find out.
- The spigot is not perfectly straight and one of the 6 x 20s had a ding that was rusting. I suspect that this portlight was smacked with or dropped on a piece of mild steel (the 6 x 20s are really heavy). These portlights are non-magnetic, so they are 316 SS. This defect does not distort the spigot, it's just a little (1mm x 0.5mm) rusting ding. If I had noticed that before install, I could have polished it out. I can still polish it out, but it'll be a bit more cumbersome on the boat.
- Before installing, make sure the hinges are tightened. I'm referring where the hinge fastens to the main part of the port light, not the hinge pin. On the workbench, release the dogs and open the port light. It should not have any wobble or play in the hinge base. If it does, flip it over and tighten the two fasteners on the backside of the hinges.
- On one of the 6 x 20 windows the hinge base was loose and I didn't know that I would be unable to tighten once the port light is installed. Now I have to live with the slight wiggle when I open or close or I have to remove, clean bedding, tighten, then rebed. That's a full day's work.
Trim ring misalignment:The trim rings are matched to each window (the bolt hole spacing is specific to each window). Even with the "matched" trim rings, I had to slightly enlarge a few of the holes because they were not exactly matched. The tapped holes in the trim ring are not exactly centered with the holes on the interior flange. The mismatch was enough to cause the machine screws to press against the hole of the interior flange and bind. Carbide burr on die grinder fixed each in a few seconds. You really need to use a carbide burr in a die grinder because this problem is seen during dry-fit and the die grinder can fix it in seconds without removing the window the countertop/workbench for filing by hand.
Installation issues:- You don't need to rent the template, just make your own out of 3/4" plywood (one for each size of window). Use the port light as the template to mark the drill holes on the plywood template and to mark the inside cutout. It is likely that you will run into problems with the template at the forward-most port light openings because those two in the v berth are so close the the deck level. With the plywood template, I just rounded off the inside corners of the template with an angle grinder to loosely fit the curve where the cabin side meets the side deck. You need some kind of template for drilling and trimming. If you can knock the project quickly, then rent the templates, but if you run into problems and the project drags out for months because of unforeseen issues or weather delays, Richard @ NFM might begin pestering you to return the templates before you finish.
- The 5 x 12s are a little tight for the V Berth. I had to trim the interior teak spacer (see attached picture) to make it fit the upper border with the overhead. I think Dale installed 4 x 14s.
Lube the threads:- Make sure you use Tef-Gel on the threads and the underside of the machine screw heads because it bears against the interior flange when you tighten. Stainless steel galls unpredictably and these threads did not feel smooth at all, even before I retapped the holes. It would be a real mess if you galled a screw during final install.
- I followed MaineSail's HowTo for installation of these windows (https://marinehowto.com/installing-newfound-metals-portlights/)
- I used about 1 and 1/4 rolls of his Bed-It Butyl tape per large window (about 3/4 to 1 roll for the 5 x 12s). There were large gaps to fill.
Cleaning butyl:After a week of hot weather and daily tightening of the screws, I cleaned off all the butyl squeeze-out. The best tool I found for this task was a demolding wedge. Like these white/rigid wedges at USComposites. You need something dense, but with just a little flex in it. These are a little denser than Starboard. http://www.shopmaninc.com/demolding_wedges.html
Combination of the wedge and paper towel dampened with paint thinner cleaned off the excess and smoothed it out. Do not use too much paint thinner and wipe it up quickly because it dissolves butyl tape.
Departures from MaineSail and from NFM video instructions:- I did not buy NFM's counter bore because Richard identified a problem with his counterbore sticking and gave a solution to spray silicon on it when drilling each hole. I thought that was a dumb idea to spray silicon in a hole where you'll need to stuff some caulking or butyl tape. I bought a counterbore from McMaster
- https://www.mcmaster.com/2919A38/
- I also did not apply any sealant to the interior of the port lights, not even the dab of silicon to the screw holes that Richard at NFM recommends. Only the external parts received butyl.
- I did not use the foam strips on the perimeter of the trim ring, as Richard recommends because Bed-It tape does not ooze under high temps.
- Mainesail's instructions were written prior to Bed-It and he used caulking to seal the exterior. I used only Bed-It
That about covers it.
More pictures at http://bodylens.com/Gallery/thumbnails.php?album=60