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Thread: Aluminum Angle

  1. #1

    Default Aluminum Angle

    I know there are many different formulations for aluminum. Is there one or a few that are well suited for marine...saltwater...in particular, applications. I plan on using angle to mount gunnel troughs. It will be covered with ply and glass and, at least in theory, will not be exposed to the elements. The rest of the plan would be to use flat dimensional stock for rub rails and this would be through bolted to the afore mentioned angle with the upper hull sides being sandwiched in between. Suggestions?

  2. #2
    Sponsor Exactboats's Avatar
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    You only have two choices with extruded aluminum angle to use. There is two grades a 6061-T6 has rounded corners generally used where structural strenght is required. Or 6063-T52 has square corners generally used where finish is more important then strenght. Both can be used in marine application.

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    Member JOAT's Avatar
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    Use 6061. Aluminum is fine in the marine environment; heck they even build entire boats out of the stuff. Leave it exposed if you can, rather than encasing in glass. If you must encase it, be sure to treat it with an acid wash and conditioner first (e.g. zepalume & alodine).

    I'm not getting a clear vision of what you're building. Can you draw a picture or better explain what it is?
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  4. #4

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    Quote Originally Posted by Exactboats View Post
    You only have two choices with extruded aluminum angle to use. There is two grades a 6061-T6 has rounded corners generally used where structural strenght is required. Or 6063-T52 has square corners generally used where finish is more important then strenght. Both can be used in marine application.
    Thanks, Exactboats...having 2 choices will make it lot easier than having a bunch to choose from!

  5. #5

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    Quote Originally Posted by JOAT View Post
    Use 6061. Aluminum is fine in the marine environment; heck they even build entire boats out of the stuff. Leave it exposed if you can, rather than encasing in glass. If you must encase it, be sure to treat it with an acid wash and conditioner first (e.g. zepalume & alodine).

    I'm not getting a clear vision of what you're building. Can you draw a picture or better explain what it is?
    JOAT, Here's a link..https://picasaweb.google.com/1119976...LK738_Op7aH9QE I hope it works...still haven't figured out how to post pics directly to this forum. The story goes like this. Bought project boat. Guy had it strapped down tight for years and crushed the gunnels. I've since pretty well straightened it out but no pic of that. I was thinking instead of buying expensive rub rail. I'd use angle on the inside..and I mis- spoke...the angle wouldn't be encased in glass..the new gunnel material would be and probably bedded in 5200 or similar in addition to some other mechanical fastener to the horizontal leg of the angle..for explanation purposes..as it really will not be horizontal. The vertical leg of the angle will be against the hull side and the flat stock will be on the outside, through bolted to the angle..the top of the hull sides will be sandwiched between the two. It will basically end up looking like a garden variety Harvey dory gunnel trough but only a couple inches deep as opposed to several inches deep as manufactured. The aluminum inside and out mechanically fastened should solve the crushed gunnel syndrome and I would think it would be quite strong as well. Do I have everyone thoroughly confused yet?

  6. #6
    Member JOAT's Avatar
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    Thnx for posting the pix, that explains a lot. I think that you're going to find the extreme flexibility of aluminum is going to just follow the existing line on the boat rather than the boat conforming to the angle. Angle is a very weak cross section. A single run of angle down that line will not make it straight. Placing that edge between 2 structural pieces as you've described should make it straighter, but not perfect. To get enough oomph, you need to use a fairly heavy material; like 1/4" web and it looks from your photo like you might be looking at a max size of about 2x2. So, while you might not get it perfect straight, you could certainly get back to a finished edge. The next question should be, how much money do you want to spend and what result is acceptable to you?
    Winter is Coming...

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  7. #7

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    Actually, and I should have taken a pic, I got it pretty well corrected. The pic in the link shows wood on one side but I later used angle on both sides with c clamps as close as possible to each other. Then gradually heated both sides with a heat gun. The process took over an hour until about a 6 foot section was uniformly quite hot, and the well crunched fiberglass relaxed and re-adopted a decent line...the gel coat did not melt or even discolor. In another life, I was a certified master goldsmith and worked for an outfit out of Chicago that would send me all over creation to hand fabricate high end jewelry pieces (100-200K range...the money was in the rocks)...while my client sat next to me and observed the entire process. The only point there is that I understand how heat moves through materials, heat sinks, etc. A good counter point is that goldsmiths, at least this one, doesn't know jack about aluminum..lol..but I'm not fearful of making an educated guess. The gunnels/rails will be the last part of the equation...but that huge indentation was making me crazy and I'm glad it's pretty much gone. Thanks for the help, JOAT...the old waterlogged pig lost about 200 lbs today..should lose another 600..she will be an interesting project.

  8. #8

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    Quote..."To get enough oomph, you need to use a fairly heavy material; like 1/4" web and it looks from your photo like you might be looking at a max size of about 2x2."

    JOAT, I'm not sure I understand what you mean when you say, "web". Do mean fiberglass? I'm not up to speed in boat part anatomy/terms. The flat where the old aluminum rub rail was seated is only 1 1/16" tall...after that, I'm into the curvature of the upper most lap. Thanks, Gary

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    Member JOAT's Avatar
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    The web is the thickness of an extruded material; and I'm talking about metals, including aluminum. A 2 x 2 x 0.25 angle is 2-inches outside across each of the legs and 1/4" thick in the middle of each side. If you only have 1-1/16" of room, you're probably looking at using a 1.25 x 1.25 x 0.188 angle. Sometimes you'll be limited to a particular size simply by what's available at the local supplier.
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  10. #10

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    Got it. Thank you for explaining!

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