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MitchK 11-18-2017 10:58 AM

Beckson Portlights
Hi all, still at the repairs on our N28. I had posted earlier about the fixed portlights leaking some. The two Beckson opening portlights are leaking too. Both around the port seal and around the flange. So I figured it was time to pull them, rebed the frame and replace the seal. The screens also needed replacement. After scouring the net, I came to the conclusion that the portlights are the originals, as beckson changed the design in 1983. Anyway, they still make the replacement parts for the older ports. Mine are the 512 model. Anyway, the lenses are not very clear anymore either. So after much research, I figured a set of new lenses, seals and screens would cost me about $200.00. I found a company that sells the complete NEW 512 portlights for $116.00 each, so I ordered a new set. With sales tax, it cane to $250.00. More than I wanted to spend, but now I have all new components that should last another 35 years! I hope to replace them in the next week or so, weather permitting. I will be using Dow 795 white structural silicon to bed them. I thought about using butyl tape, but for this purpose, I think the 795 will be a better product. When I pull the fixed portlights with the aluminum frames, I will use the butyl tape for those. Need to get some butyl ordered. I hear there re some issue with the run of the mill butyl available compared that supplied by an on line company specializing in marine products. Anyone have any experience with their Bed-It Butyl Tape? Is there really any difference? I've use butyl before, and actually had a few rolls of it, but got rid of it a few years ago thinking I did not need it anymore. That was a mistake!


CVAT 11-18-2017 01:27 PM

Re: Beckson Portlights
Problem with Silicon has been reported on these forums over and over, Great for bedding Acrylic, terrible for anything else as nothing sticks to silicon, not even silicon. See Mainesails self-help at:Re-Bedding Deck Hardware With Bed-It Tape Photo Gallery by Compass Marine How To at

I used 795 in the navy for water intrusion prevention on F-14's, to get it to seal properly we had to sand down to bare metal and repaint all surfaces to get it to bond correctly. In addition, all hardware, screws and washers and such had to be replaced with new ones. So for a simple alignment of a "Black Box" with 4 screws on a side we would have to disassemble the entire box, all paint a to bare metal where the 795 was in contact; allodyne ( a conversion coating for aluminium and corrosion preventive) the aluminium, prime and top coat the painted surfaces. Replace the 16 screws, lock washers and sacrificial washers with new ones, we had tried to use an ultrasonic cleaner to clean them to no avail. This was all for a 5 to 10 minute alignment, the supporting maintenance took on average 3 days, to disassemble, send to airframes shop to be stripped and repainted. The good news is that if we did this the "Black Box" stayed out not needing repair for months even years, the bad if a part was skimped or not done, this was often the "black box" was back in for repair due to water and or other fluid intrusion and required repair now not just alignment. So I would personally use 795 only if necessary and would use Butyl Tape or similar bedding above the waterline.

roverhi 11-18-2017 02:16 PM

Re: Beckson Portlights
Are Beckson ports compatible with Butyl??

CVAT 11-18-2017 02:55 PM

Re: Beckson Portlights

Originally Posted by roverhi (Post 2051288770)
Are Beckson ports compatible with Butyl??

What isn't compatible with Butyl? other than below water line.

MitchK 11-18-2017 08:34 PM

Re: Beckson Portlights
Beckson specifically says to use silicon. I figured if that is what the manufacturer recommends, then that is probably what I should use. The Dow 795 seems to have a pretty good reputation for sealing plastic to other surfaces. Since the Beckson port is made of plastic, it seems to make sense to use silicon. We'll see what they are currently bedded with when I remove them. Didn't get a chance to work on them this weekend. I spent today installing class V receiver on my truck. Tomorrow, I will be pulling our Clipper Marine CM26 out of the water for the winter, so probably will not get to it this weekend. Maybe over the Thanksgiving weekend I'll get a chance.


CVAT 11-18-2017 11:53 PM

Re: Beckson Portlights
Then use silicon because your mating plastic and the manufacturer specifies it. 795 is a good product, just requires a lot of prep, ensure your surface is clean and free of silicon and other contaminants as with anything prep work is the most important aspect of the job, the better the prep the better the job. If silicon was used just make sure you remove all of it prior to attempting to bed the new portlights. Good luck, and be meticulous, done right 795 seals well, the problem with it though it is so easy to do wrong, any residue will cause it to fail. Good luck again and take your time.

MitchK 11-23-2017 03:49 PM

Re: Beckson Portlights
Hi all and Happy Thanksgiving.
Just a short update on the N28-2 repairs. I have leaks in both Beckson port lights around the flange and the seal. So purchased a set of new ones. Anyway, I do not know what they used when they bedded them last, but it is a major pain trying to get them out! Finally got the outer bezel off, and cut the sealant as best I could. Frame would not move. Made up a improvised pressing fixture with what I had on hand, and started to apply force. Unfortunately, the 1/4-20 bolts I was using galled, and I had to cut the bolts to get the jig off so I could close up the window for the night. Put a small bead of marine silicon around the opening to close it up for the night. I was just trying to keep the rain we were expecting form soaking the inside of the boat. I did put a couple of buckets under the port to catch any leaks. The frame had separated over about 1/3 of the length top and bottom before the bolts galled. I should have used a bit of oil on them before I started. Oh, well, I picked up some 5" carriage bolts and made a couple of new press plates from some 3/4 x 4" pine boards. Tomorrow it is supposed to be clear, so I will get back to the removal then. I plane on routing the edge of the opening with a trim router and 45 degree cutter to make sure there is room for a nice bead of sealant when I put them back together.


Capt Len 11-23-2017 10:22 PM

Re: Beckson Portlights
Partial rolls of butyl tape are often found in the dumpster at auto window repair shops, Of course some feel the need to spend big to cover lack of skill and initiative.

MitchK 11-24-2017 11:25 AM

Re: Beckson Portlights
Capt Len,
Thanks for the tip on locating butyl tape. I'll keep that in mind if I am ever near a auto window repair place. Not entirely sure what the rest of your post is supposed to mean.

sailingfool 11-24-2017 04:27 PM

Re: Beckson Portlights

Originally Posted by CVAT (Post 2051288746)
Problem with Silicon has been reported on these forums over and over, Great for bedding Acrylic, terrible for anything else as nothing sticks to silicon, not even silicon. ...

FWIW, in addition to installing Beckson port frames with the Beckson recommended silicone, in the past when I've replaced the lens in two different types of deck hatches, both manufacturers specified to use silicone. The Bomar folks even ship tubes of their own labeled silicone...

For the OP, I suggest using all new hardware with the new ports, any re-used bolts are a likely source of leaks...

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