Patch My Leaky Aluminium With Fibreglass?

Discussion in 'Materials' started by abrogard, Apr 24, 2012.

  1. pauloman
    Joined: Jun 2010
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    Location: New Hampshire

    pauloman Epoxy Vendor

    epoxies are generally too brittle to work.

    best is an aluminum moisture cured urethane (MCU) - a few coats along the seams. - only works with small leaks. goggle aluthane.

    paul oman
  2. Ace Dragon
    Joined: Aug 2012
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    Location: Alaska

    Ace Dragon Polyurea and Spray Foam

    Polyurea will do it.

    Not a do-it-yourself product, but will do it. find a qualified applicator in your area and never have a leak again.
  3. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    What's the downside to welding all of the rivets and seams? Hard to beat one solid piece of aluminum.
  4. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    You mean besides heat distortion opening all the seams, welding light gauge sheet aluminum, distorting the panels themselves, insuring a perfect, water tight weld on every seam and hole? No I can't think of anything other than these trivial bits of heartache.
  5. Ace Dragon
    Joined: Aug 2012
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    Location: Alaska

    Ace Dragon Polyurea and Spray Foam

    Unless you can do it your self - aluminum welding does cost.

    sun in my screen so no telling what I will type. the boat is of thin metal more than likely, it would take a quality machine and good welder and if hired out could cost more than buying a new boat.
    Polyurea project would go something like this. Carry boat to applicator. one hour for his machine to heat up, one hour to sand blast to get a min. of 3 mil profile, desalt the metal = 30 minutes = after drying it would take 30 min to spray. Cost is reduced if no masking is required - let him coat the complete out side.
    You may want a different color but polyurethane paint hold well to polyurea. cost for a simple 20 ft. boat could be around $1,100.00
  6. bntii
    Joined: Jun 2006
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    Location: MD

    bntii Senior Member

    Ace- how is the product holding up so far in the field on boats?
    Any bonding issues?
    Equally good to go on FRP, steel, Al & wood?

    How is corrosion dealt with on Al and steel hulls?
    I did see your other thread- I will be interested to see if the how the product comes along in the recreational boat industry here on the East Coast US.

  7. tunnels

    tunnels Previous Member

    search back aways !!

    Some where a few months ago was the almost exact same post !! go look and see !:p
    West system have a rubber toughtend epoxy at sticks really well and is semi flexable for just such a occassion !!;)
  8. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    Some of us are good welders with the right equipment. Most of us can respond to a question without resorting to sarcasm.

    PAR added to ignore list.
  9. Ace Dragon
    Joined: Aug 2012
    Posts: 44
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    Location: Alaska

    Ace Dragon Polyurea and Spray Foam

    No sarcasm or self promotion intended.

    I received a message that I might be self promoting - Not intended. I just gave a cost as an point of info.

    I think I will be leaving this site.
    As to salt water boats - we desalt the metal after sand blasting.
    We have created a coating that is the first to hold up to silt filled ice of Cook Inlet, and Phantom boats have been using a polyurea for a few years now for rock protection.
    Polyurea can hold up quite well if substrate is prep'ed correctly.
    Polyurea is a plastic so it can and has been used for electrical protection.
    There are many different types of polyurea's and the correct one has to be spec'ed out.
    Have fun guys.
    1 person likes this.
  10. Eelco
    Joined: Apr 2020
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    Location: Amsterdam

    Eelco Junior Member

    So many conflicting opinions on the matter.

    I dont have any practical experience, but here is what Id say based on a theoretical materials / composite understanding. Glass/alu is in the right context a very well respected combination.

    Small patches with poor surface prep will come loose easily. Even with good prep they might. Glass and alu are fairly different materials, one easily plastically deforms, other does not, etc. This intrinsically creates a risk of peeling at the edges if you recieve and kind of tap there, and once that starts, stress concentrations will only get worse and do the rest.

    With good surface prep, and covering a large area, prefereable the entire hull wrapping around the deck, this seems like a winning combination that could bring back an almost dead alu boat, or may even be quite a decent idea for a freshly welded alu boat. With such a large bond area, and the edges wrapped around protected from impact, risk of delamination need be no greater than a glass-glass bond. You still have all the safety benefits of your ductile alu, you get the corrosion resistance of glass on the outside, and should you get a crack in the exterior glass, you have all the easy of repairability of patching glass, rather than having to deal with the alu.

    As has been suggested a flexible epoxy sounds like a possibly good idea if you are not relying on the glass for stiffness, but basically just as a toughened paint coat. Tried finding quantitate information on aging of flex epoxies before though without much success and its not clear to me if after 5 years you dont end up with an epoxy thats just as brittle but weaker.

    Thats all theory though, and you dont see this a lot in practice from what I can tell. Maybe because its a silly idea in ways not yet discussed here. Maybe because not every good idea has had time to spread yet. I dont know, but I dont see any downsides on paper, aside from a slightly higher cost and weight than a coating without glass in it, but it seems like a tradeoff worth considering for the maintainability.

  11. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    Looking at the way chewing gum sticks to shoes, I am "all-in" on chewing gum for this job. I can't help on brand or flavour ! o_O
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