Steel hull closed cell foam insulation question...

Discussion in 'Materials' started by parkland, Apr 9, 2013.

  1. parkland
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    parkland Senior Member

    So I've been researching blowing commercial closed cell foam in a steel hull.
    Obviously the negatives are that it makes it impossible to inspect the inside of the hull, and can trap moisture. (and fire hazard, which I'll leave out for now).
    I've also read a lot about different rust prevention methods... from cheap ideas like fat, oil, grease, wax products ... to expensive epoxies, paints, etc.

    So it seems like many methods work, arguably to varying degrees, but in the end, none of them work "forever", they all might fail eventually, resulting in needing to remove the boats interior, tear out all the foam, and start over.
    I believe up to this point, I have stated facts, not opinions. Please correct me if that is incorrect.

    Now, I also came across something that I found interesting, and that is old steel boats that had a new steel skin welded over an old riveted hull. The install grease nipples, and pump grease between the plates, to remove air, and prevent rust between the plates. There are boats that had this done 40+ years ago, and still no rust even to this day, between the plates. (as per what I've read. ) So it would seem from this method, that grease can do an excellent, if not PERFECT job of rust proofing, if it is used in certain ways.

    So, my question to you guys is this, involving the information from the above, what do you think about taking a steel hull, "painting" it with grease, maybe 1/16" to 1/8" thick, and blowing closed cell foam over top?
    The foam should keep the grease from being rubbed or washed away, and in the event it does need to be removed, the grease should allow the foam to come out rather easy?
     
  2. keysdisease
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    keysdisease Senior Member

    The foam will never stick to the grease and you will end up with a scary mess that will be very difficult to clean up.

    Why not use coal tar epoxy and then fiberglass insulation batting? Putting combustible insulation on a non combustible structure is not good practice under any circumstances. The up-charge (I would guess very little) in cost is negligible when amortized over the life of the vessel.

    $.02 :cool: Steve
     
  3. parkland
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    parkland Senior Member

    But thats the good part; that the foam doesn't stick to the grease. If the ribs had some flat steel parallel to the hull, that would hold the foam in, but the foam would essentially be sitting on the grease; not the metal.

    Coal tar epoxy, and fiberglass batting, means there would be moisture sitting on the metal lots.
     
  4. parkland
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    parkland Senior Member

    I wanted to quote this:



    The Black Hawk is one of Canada’s oldest lake boats with a history of service spanning 108 years. Built in Buffalo, New York and originally christened the ‘Alert’ she sailed as a tugboat and freighter under U.S. registry on the Great Lakes until 1916 when she was transferred to British registry and a new base of operations at Southhampton, Ontario.
    In 1944, a year before the end of World War 11, she became a tugboat at Port Arthur (now Thunder Bay), Ontario, a career that lasted until 1951 when her hull was transported overland by rail to Selkirk, Manitoba. The hull and superstructure were re-built by Riverton Boat Works and she was renamed the ‘Douglas M’ for her new assignment as a Lake Winnipeg freighter for Northern Lakes Fisheries Co. Ltd.
    The original hull was riveted steel and Riverton Boatworks made significant structural changes to the vessel. All rivets below the waterline were welded, 3/8 inch steel plate was added below the water line, and waterproof grease pumped between the two plates. This gave the ‘Douglas M’ virtually ice-breaker capabilities.

    So it seems like grease is very good at preventing rust in a cavity... ? That boat is still in use today...
     
  5. parkland
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    parkland Senior Member

    I guess I'm assuming that grease that is protected, so that it doesn't get washed or scuffed off the surface, should last a damn long time without intervention, am I wrong?

    How long would coal tar epoxy last if nothing rubs it away mechanically?

    Let's pretent we had 2 identical steel sheets, sitting in the back yard on saw horses, and painted one with CTE, and the other we coated in grease, which one would rust away 1st with only water falling on them, and exposed to nothing except air and water? (No scrubbing, or abrasions to remove either product)

    I appreciate the input, and patience with my lack of understanding, but thank you for opinions and sharing knowledge.
     
  6. keysdisease
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    keysdisease Senior Member

    The grease between steel plates you base this idea from was a way to increase the longevity of a steel work vessel from the middle of the last century. Now not all old ideas are bad ideas, but you're not increasing the life of an existing vessel, you're reinventing a way to insulate one.

    I think what you describe is the foam adhering to framing and the grease protecting the plating in between. The grease in the plating of the Blackhawk was for all intent, captive between two layers of steel. In your scenario on a hot day when the grease becomes less viscous it may very well all end up in the bilge. The concept of the foam adhering to the framing and "Floating" on the grease may work in a static environment, but in a dynamic environment the foam might very well structurally fail and then you have big greasy pieces of foam adrift in the vessel.

    Not saying what you describe won't work, but you're trying to reinvent the wheel when there are several existing methods of insulating steel hull plating that are in my opinion, better and may be less expensive.

    To answer you question about a test between CTE and grease:

    "Let's pretend we had 2 identical steel sheets, sitting in the back yard on saw horses, and painted one with CTE, and the other we coated in grease, which one would rust away 1st with only water falling on them, and exposed to nothing except air and water?"

    I'm pretty confident the grease will fail long before the epoxy will, by a measure of years. Water abrasion created the grand canyon, grease will wash away pretty quickly compared to an epoxy that is a vapor barrier and that has excellent abrasion resistance.

    $.02 :)
     
  7. parkland
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    parkland Senior Member

    I suppose grease does stand a much better chance of migrating off of where it's supposed to stay. Especially if it gets hot I guess.
    Grease and other loose petroleum products have a neat feature though, the ability to creep into cracks and spread out a little bit.

    I never used coal tar epoxy before, so I guess I am underestimating it's ability.
     
  8. tomas
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    tomas Senior Member

    Parkland, I like that you are not shy and that you're making good use of the forum by posing questions and exploring ideas. Hopefully, it will eventually coalesce into your own build thread at some point in the future.

    My only suggestion at this point would be to keep a second option open by looking for good deals on boats with suitable hulls that meet your needs but are inexpensive due to other problems they might have. This would potentially save you both time and money which you'll still need for the interior build, electrical and mechanical details. Those details are killing my design spiral so far. :(
     
  9. parkland
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    parkland Senior Member


    Seeing as I want a 8.5 ft wide 32-40 ft boat, nothing really exists that size. Nothing other than a pontoon deck boat, anyways.
     
  10. tomas
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    tomas Senior Member

    If you focus on houseboat hulls, you may find it, usually in fiberglass, sometimes in aluminum.

    This example is close (probably sold by now):

    http://oklahomacity.americanlisted.com/boats/75030-trailerable-houseboat-hull_22994617.html

    [​IMG]
     
  11. parkland
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    parkland Senior Member

    Thanks, I did see that, but it's really a pond boat type of hull.
    19" sides don't give much room for error.

    If I knew how to work with fiberglass, I would probably jump on it.
    Looks like it could take a lot of work.
     
  12. SamSam
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    SamSam Senior Member

    I haven't followed your threads so I don't know what you're "proficient" in. I guess not glass. Wood, in some form? Metal?
     
  13. parkland
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    parkland Senior Member

    I'm not a boat builder, I just want to build a boat.

    I'm decently experienced enough with steel, but only to a hobby level. I did work in a metal fab shop once, but its just a hobby.
    I think I'm pretty good at understanding a lot of things, I think I could build a fiberglass boat, maybe even an aluminum one, but the question would be, how good of a job lol.

    I don't have a lot of time off, and I'm not a millionaire, so expensive mistakes would probably mean I'd end up with a canoe. haha.
     
  14. El_Guero

    El_Guero Previous Member

    Steel.

    It rusts.

    Placing grease on the inside will keep the inside of the two sheets from rusting - kind of. But, the outsides of both plates of steel will rust anyway. And unless you use the right grease and right pressures to squeeze it in, you won't keep spots from rusting in the middle anyway.

    And you are forgetting the environmental disaster waiting to happen.

    Using your simple houseboat above, 1/8 * 8 *12 * 30 = about 2.5 cubit feet of grease. Not including sides.

    A couple hundred pounds of grease waiting to spill?
     

  15. El_Guero

    El_Guero Previous Member

    If this is what you want: "Seeing as I want a 8.5 ft wide 32-40 ft boat, nothing really exists that size. Nothing other than a pontoon deck boat, anyways."

    Then why wouldn't a pontoon deck boat fit the bill? Aluminum pontoons are easily bought. You can build up from there.

    And if you use 2, 3, or 4 pontoons, you would have a fairly stable platform.
     
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