Portlight Frames 316 or 6061?

[SailAwy]

Hi gang,

I'm having outside trim frames made for my portlights, and I'm wondering what your thoughts are on using 6061 aluminum vs 316 SS for the material. 316 is about twice the cost, so looking for a compelling argument to pony up the extra, or if it's just fine to use aluminum. Whichever option I choose, I'm going with a brush finish (if that makes any difference), but mostly curious about the long term wear on 6061 from saltwater. I doubt it would come anodized from the factory, but I don't think doing that myself would be all that complicated, so that would possibly be an option too if required to protect the finish for longer period of time.

Thanks in advance, and Happy New Year!

[SailAwy]

I should also note, the trim will be for aesthetics only, and will serve zero structural purpose. I'm mostly just juggling between how well the finish of either option holds up over time.

Thanks!

[SailAwy]

Hello...is this thing on? [emoji38]

[Cheechako]

316 for sure. Aluminum will pit and corrode and weld itself to the fasteners. Proper anodizing is not easy and must very thick, well done, to hold up even marginally. Most masts and fitting corrode with SS fasteners even if anodized.

[SailAwy]

Originally Posted by Cheechako

316 for sure. Aluminum will pit and corrode and weld itself to the fasteners. Proper anodizing is not easy and must very thick, well done, to hold up even marginally. Most masts and fitting corrode with SS fasteners even if anodized.

Thanks for the info. Not sure that I would use fasteners if going the aluminum route. They would be lightweight enough that I could probably just use lifeseal or 4200 to tack in place and provide for extra seal around portlights.

[clockwork orange]

I'm a little confused, if you are having them custom made I would expect the ss ones to be more than twice the price as they will need to be either electropolished or mechanically polished or they will rust where they were cut. To paint them you would want to sandblast them first and at least prime them immediately. Polishing ss is as much for corrosion resistance as it is for looks. They will also weigh 3x as much for a given thickness. If using 6061 you should have them anodized for the best protection, the process is not very expensive, the place I use charges me a $50 minimum but that would easily cover all your frames and a lot of other stuff too. They charge by the weight of the parts being anodized and you can get a lot of pieces done within that minimum charge. If you are just planning on painting them anyway i would make them out of G10 fiberglass sheet as it will accept paint better than either of the other options and be much happier in a marine environment and bond well and you can probably make them yourself with minimum tools.


Steve.

[SVTatia]

Originally Posted by SailAwy

Hi gang,

I'm having outside trim frames made for my portlights, and I'm wondering what your thoughts are on using 6061 aluminum vs 316 SS for the material. 316 is about twice the cost, so looking for a compelling argument to pony up the extra, or if it's just fine to use aluminum. Whichever option I choose, I'm going with a brush finish (if that makes any difference), but mostly curious about the long term wear on 6061 from saltwater. I doubt it would come anodized from the factory, but I don't think doing that myself would be all that complicated, so that would possibly be an option too if required to protect the finish for longer period of time.
Happy New Year to you too...

Thanks in advance, and Happy New Year!

I am not sure how many portlights you have or their size, but if this is just for esthetics, which I understand is just to have a "frame", there is absolutely no reason to justify 316 stainless. Even if 304 was that much cheaper, I would still go with aluminiunm... which I did by the way.
Once you have the frames cut, do the finish you like (brush or shiny) and have them anodized, which you can do it very inexpensively or paint with a polyurethane silver or the same color as the deck. I have done both on different boats, one example below.

[landonshaw]

They look great. Where are you having the work done? My portlights are leaking and in need of new gaskets, and possibly frames. If I may ask, when replacing the gaskets, can you purchase gasket material that is in straight lengths and then form around the corners, or does it have to be per add to match the radius of the corner?

Looking for as much information before I start the project. Thanks

[SVTatia]

Originally Posted by landonshaw

They look great. Where are you having the work done? My portlights are leaking and in need of new gaskets, and possibly frames. If I may ask, when replacing the gaskets, can you purchase gasket material that is in straight lengths and then form around the corners, or does it have to be per add to match the radius of the corner?

Looking for as much information before I start the project. Thanks

It depends. Do you have opening ports or deadlights as pictured?
My deadlight frames and new lenses (cast acrylic or Plexiglas) were re caulked with Dow 795.
For the opening ports, I purchased the EPDM flat rubber strips with adhesive back from McMaster Carr. Measure the channel on the ports, the height needed and the total length in feet (the rubber conform to the curves). Then check the equivalent size from their site below, look for "Weather-Resistant EPDM Rubber Sheets and Strips"

https://www.mcmaster.com/rubber

[landonshaw]

Mine are Deadlights, do not open. Thank you! I will review what you have sent.

[Woodland Hills]

Why would you you use a 6000’s series alloy instead of a 5000’s? Do your research: 5000 series is specifically made for marine usage due to it corrosion resistance. 5083 is the strongest non-heat treatable alloy. 6061 is simply the most common of the heat treatable alloys out there, fine for general purpose use, but this isn’t general purpose usage.

[SailAwy]

Thanks for your reply, Woodland. Researched plenty. Comfortable with my choice of aluminum. With that said, 5083 (or 5086) would've likely been my first choice, but the machine shop only provides options for 5052 in the 5### series alloy. 6061 still contains many of the anti corrosion properties as 5083 & 5086. Had this project been for underwater use, or more importantly, required any bit of welding with the need for structural integrity of said welds in salt environment, then 5083 would certainly be the better option. When anodized, 6061 is a good compromise (and only a few cents more than 5052)

Thanks to all who've provided input and shared their experience.

[SailAwy]

Originally Posted by SVTatia

I am not sure how many portlights you have or their size, but if this is just for esthetics, which I understand is just to have a "frame", there is absolutely no reason to justify 316 stainless. Even if 304 was that much cheaper, I would still go with aluminiunm... which I did by the way.
Once you have the frames cut, do the finish you like (brush or shiny) and have them anodized, which you can do it very inexpensively or paint with a polyurethane silver or the same color as the deck. I have done both on different boats, one example below.

Looks great! Going the aluminum route. Was only contemplating SS due to potential of using as extra thru-bolted reinforcement, sort of like a backing plate, which I have 86'd after determining it woud've been an overkill. Story of my life. Ha!

Thanks again!