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Aluminum and salt water

Discussion in 'General Yachting Discussion' started by FlyingGolfer, Jan 8, 2021.

  1. FlyingGolfer

    FlyingGolfer Member

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    As an aviation guy, I am astonished to learn some yachts have aluminum hulls. Heesen for example. I would to love to know how corrosion is prevented and treated.
  2. Capt J

    Capt J Senior Member

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    Most yachts over 130' are all aluminum hulled (some steel as well on displacement ones). Westport was the first yacht builder to start making yachts over 100' in fiberglass. Prior to that pretty much anything over 75' or so was aluminum. It takes a huge commitment ($$$) to build a fiberglass mold and you have to sell several just to pay for the tooling costs. Aluminum allows you to build a totally different yacht each time. They have special primers and paint inside and out. Some use an epoxy coating on the inside. You still get corrossion bubbles on the exterior under the paint after 5+ years on the paint job that need to be sanded down and fixed.
  3. NYCAP123

    NYCAP123 Senior Member

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    Some? A lot, along with a lot of workboats and even CG vessels. I'm not aware of issues with salt water.
  4. FlyingGolfer

    FlyingGolfer Member

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    I had thought most hulls and structure assemblies were steel. Guess not!
  5. Capt J

    Capt J Senior Member

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    No, it's too heavy for a lot of designs. Steel hulls are the strongest when built properly. However, on a lot of motoryachts, they find steel too heavy. Some builders use a steel hull and aluminum superstructure. I'd say the majority of yachts over 100' are aluminum. Steel is not without it's corrossion issues either.
  6. Oscarvan

    Oscarvan Senior Member

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    Eh, you're joking right?..... Salt an aluminum are an easy recipe for corrosion and need to be kept separated at great effort and expense. No to mention the problems with dissimilar metals and galvanic action. Slacking on any of that is a death sentence. Notice you don't see a lot of old shaggy aluminum boats.
  7. Capt J

    Capt J Senior Member

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    I have seen and run a few aluminum crew boats from the 1950's,1960's, and 1970's, and when I tell you they were run hard and put away wet, they were. They were still in pretty good condition and useful in a commercial setting.
  8. NYCAP123

    NYCAP123 Senior Member

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    Learned something new. 1950's? I've run them built in the 60's and up, and yes they're run hard and keep coming back for more. The big problems with aluminum hulls wasn't salt water corrosion, but electrolysis from dissimilar metals and finding bottom paint that worked and held to the surface. Aluminum is used in boats for the same reason it's used in planes. It's light and requires very little maintenance. Aluminum, steel and fiberglass all have their good points and bad and different materials they need to be pared with.
  9. Capt Ralph

    Capt Ralph Senior Member

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    Don't get lower drive units confused with alloy yacht hulls. That is comparing weeds with granite.

    I have delivered and serviced converted aluminum crew boats, LCM/LCUs, Roamers and Strikers. With the original alloy plates, they may out live some of us.
    It takes a better alloy, A better welder and material and some care for these antiques to last so well.
    Modern yachts built properly (I'm sure they are) will outlive us and more.

    On a green note; Alloy boats are recyclable. Melt your boat down back to ingots and start again.
  10. Capt Ralph

    Capt Ralph Senior Member

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    Ever notice how long a coke can last in salt water?
  11. DOCKMASTER

    DOCKMASTER Senior Member

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    Our company has an entire aluminum shipbuilding division. Lots of boats and ships that are 100% aluminum. Some get painted, some do not. You just have to use the correct type of aluminum. Also, thousands (probably millions) of small aluminum boats out there. Builders like North River, Armstrong, weldbuilt, etc - all 100% aluminum.
  12. bayoubud

    bayoubud Senior Member

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    Marine grade aluminum holds up well in saltwater as long as maintained properly. Maintaining a yacht finish if you want to show off at the dock requires regular attention. In commercial use aesthetics is not always a priority, actually you don't have paint it above the waterline. There are a lot of old aluminum boats still floating. One of my favorite SF boats designs is the Strikers. All welded construction eliminating fasteners, caulking, laminate coring, blisters, no delamination, not to mention fire resistance and strength is appealing.
  13. rtrafford

    rtrafford Senior Member

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    Absolutely. Aluminum hulls are built with 5052 or 6061 aluminum alloy, are typically a 6-7mm skin, and the metal is primed and sealed on both sides of the wet surface. If you keep the metal coated and clean, and if you maintain the electrical properties of your vessel carefully, aluminum is in many ways superior to steel, albeit a lightly higher electrical potential. The cost driver in the maintenance of my boat is mostly driven by its size, not its material.
  14. rtrafford

    rtrafford Senior Member

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    Yes, I'd be tempted by a Striker 70 if I one day want to return to the world of SF. In fact, it would likely be at the top of my list.
  15. hat4349

    hat4349 Senior Member

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  16. Capt Ralph

    Capt Ralph Senior Member

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    I worked on an original 1970-71, Striker 44. I miss that boat.
    I remember that Striker 70 at the southern tip of Marsh Harbor entrance. Her running at speed looked awesome.
  17. bayoubud

    bayoubud Senior Member

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    That 70 is a big ship. If I switch back to a SF I'd consider the Striker 62. Actually, I have thought about it, still hanging on to my tackle...;)
  18. Danvilletim

    Danvilletim Senior Member

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    Oh Strikers still had blisters! We had one two boats ago. It was a tank.
  19. Oscarvan

    Oscarvan Senior Member

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    OK, I sit corrected. I actually have an 80's 24' Starcraft sitting in my back yard. It's a project which will need to go down to bare hull..... in my copious spare time. Hull is in very good shape. It was a Great Lakes boat.
  20. Capt Ralph

    Capt Ralph Senior Member

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    Bottom blisters? Fairing putty coming loose?
    Corrosion blisters may accrue under the paint and fairing topsides.

    I warned a past Roamer owner not to let the paint yard take a paint job down to bare alloy.
    They did, Job looked great. Within a year the new paint was blistering up everywhere.
    Never defeat the factory primer on an alloy boat.
    Last edited: Jan 8, 2021