Rebedding Beckson portlight

Maine Sail · Sep 8, 2011

FourPoints said:
Starboard side portlight developed a nasty leak all of a sudden (my efforts to tape over the portlights for Irene, and then remove that tape are most likley to blame), and I had easily a couple gallons or more came in with all the rain we had the last few days...

I've read some of Stu's posts on the subject:
http://www.c34.org/wiki/index.php?title=Rebedding_Beckson_Ports
http://forums.oday.sailboatowners.com/showthread.php?t=77908

I'm not really asking about how to do it so much as if I should still be using the same sealant mentioned, the Dow 795, or should I be using some of Maine's Butal tape?

When Hunter installed them, 21 years ago, they used something white that may be 4200 (at least it's not 5200!)... I'm slightly tempted to use 4200 again only because it lasted 21 years, and I think the only reason it failed is that it looks like it never had a good seal on the top, and I might have ripped a tiny bit of it loose it when removing the tape, ripping a large section loose...

Guess while I'm at it I better plan to do the port side as well, and maybe the one over the aft double berth.

For Becksons use the silicone/Dow 795. Polyurethanes and Polysulfides will leach the plasticizers out of the plastic and they will prematurely become brittle. Hunter likely used silicone because Beckson has been adamant about the non-use of PU and PS sealants for as long as I can remember. Though I'd love to sell you some these plastic ports are not the best use for butyl, IMHO, unless sealing the port to the hull with butyl and then installing the trim ring with silicone.. For metal ones butyl is great for everything but the plastic ones just use silicone. Be SURE the surface is 100% clean and free of the old silicone or it will fail & leak again.

John Nantz · Sep 8, 2011

Chamfer the coachroof cutout

Standardly the rough-in, or cutout, in the coachroof for the ports are just a plain cutout. The cutout makes a 90-degree angle to the outside of the coachroof.

Note that the backside of the Beckson trim rings have a 45-degree chamfer on them where they abut the port. What would really help is to file a similar chamfer around the port opening rough-in just opposite the Beckson one. This will help to create a kind of a "gasket", at least a much better one, than not doing it.

No need to put sealant on the cabin side (inside) of the port because water should never get there, and besides, if it did you would really want to know about it.

Be very careful when removing the trim ring because old ones are very easy to break. Use a very thin blade to get under it. Better yet, just buy a new port! The glass will be much clearer, at least for a while.

Some editorial comment: If your ports are original there may have been a hole drilled in the rain-drip section (or whatever they call it). If there is one, make absolutely and totally sure this hole goes to the outside of the trim ring. If no hole drilled then disregard this comment.

Maine Sail · Sep 10, 2011

FourPoints said:
Where can you get the Dow 795? Just stopped by west marine they don't carry it, and it looks like defender does not carry it either.

I'ts not a "marine" product so any Grainger should have it or just use Google...

Fred Villiard · Sep 10, 2011

Try www.mcmaster.com

Fred