Steel hull isolation: alternatives to foam?

Discussion in 'Metal Boat Building' started by MarijoV, Apr 9, 2009.

  1. Brent Swain
    Joined: Mar 2002
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    Location: British Columbia

    Brent Swain Member

    Aluminium is far more forgiving when it comes to insulating the bilges. May even keep the dropped penny from corroding thru. However , how new is the boat he did it to? Maybe some regrets down the road a few years. I find insulating the underside of the floor boards does the same thing, and still lets you keep an eye on the metal.
    I find the bilge is far more corrosion prone than a few inches above it. There is no guarantee that there is no airspace between your insulation and the metal ,nor guarantee there will never be any, and that is always a potential problem.
     
  2. apex1

    apex1 Guest

    Well you know Brent, that all boils just down again to the quality of application and / or maintenance. Correctly executed and designed there is no problem.

    And on top of that, a synth. rubber does´nt require latex paint (not the worst solution on PU foam), to remain fire resistant in tricky conditions.
    Latex by the way is processed into rubber, Armaflex AF is a synth. rubber................sic

    The bilges we are talking here are even the engine room bilges, when there is a sufficient "drip pan" under the mains, gennies and other "pigs". Though it schould be covered by Armaflex R90

    Regards
    Richard
     
  3. majay
    Joined: Apr 2010
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    Location: Ottawa, ON

    majay CN 35

    I'll get the torch and we'll cut it up then...

    Good lord, those are terrible thoughts. I have a soft chine corten steel yawl over 30 years old that seems to be doing quite well according to recent survey. I don't think I will be scuttling her yet...even though my welds have long been replaced by high quality duct tape.
     
  4. apex1

    apex1 Guest

    :D :D :D nice, thanks.

    Cor-Ten B is not difficult to weld and widely used by the industry.. In the late 50ies and early 60ies many of the open harbour launches / tugs in the ports of Hamburg and Bremen were built in Cor-Ten. They worked really hard and some still do, lasting better than their mild steel competitors.
    But I am sure, our German yards did not know that expert from NZ.;)

    [​IMG]
     
  5. Brent Swain
    Joined: Mar 2002
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    Location: British Columbia

    Brent Swain Member

    Having lived aboard steel boats year round, mostly in BC, for the last 34 years, I have found no reason to insulate under an engine or in the bilges.
    Having put carpet on my floor for the winter, my blges are dusty dry. Insulation in the bilges , or under an engine, is a big mistake . If there are problems under it. you have no way of knowing until it becomes a major problem. This is not the case with a well epoxied bilge, with no insulation.
    On s a power boat, a drip pan may be adequate, but when sailing, and occasionally putting the rail under, the odds of oil escaping a drip pan are high. I build the hull under the engine into a drip pan. Any oil leaks preserve the steel well.
     
  6. apex1

    apex1 Guest

    I had only motorboats in mind when i posted that, due to the fact that I pointed towards Dashews Windhorse.
     
  7. jboswell
    Joined: Mar 2010
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    Location: Los Angeles

    jboswell Junior Member

    Hey guys, anyone have a number for an Armacell retailer/dealer here in Los Angeles? I have been trying to get someone/anyone on the phone and I haven't gotten anything, even tried an email..

    I wanted to buy some (1/2") Armaflex for my Buccaneer 295 to insulate against the condensation, there is a horrendous amount of it during the winter months and I would like to liveaboard and not have it be a swamp.

    Joe
     
  8. apex1

    apex1 Guest

  9. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    For a boat in cold water, if you don't insulate below the waterline, doesn't water constantly condense on the cooler steel? I've been in an uninsulated houseboat hull in the Mississippi River on the Minnesota/Iowa border and in the spaces below the cabin floors and decks, you could trace the waterline by heavy rust. Primer above and heavy layers of flakey rust below. Even if it was coated with epoxy, wouldn't the steel below the waterline be all wet from condensation?
     
  10. capt littlelegs
    Joined: Apr 2010
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    Location: England

    capt littlelegs New Member

    The water is still warmer than outside air so the bilge has insufficient temperature difference to cause significant condensation and in any event it is not affecting the accommodation. Any dampness in the bilge will come from internal air reaching the hull sides and the resulting condensation running down or other leaks. A damp, poorly ventilated bilge will rust, even more so with insulation that will absorb and hold onto moisture. If the bilge is painted some way it will protect it from contact with water for a while.
     
  11. Brent Swain
    Joined: Mar 2002
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    Location: British Columbia

    Brent Swain Member

    I had lots of condensation down there, before I put the carpet down to stop interior heat from making a huge difference in temperature between the air in the bilge and the steel . Putting carpet down reduced the condensation by 80% , insulating the underside of the floor eliminated most of the rest. Ventilation of warmer inside cabin air in the bilge will increase the temperature difference between the air and the steel , by increasing the temperature difference, and thus increase condensation. One could possibly use this as a built in dehumidifier to condense cabin air out into the bilge, and then pump it out. Dehumidifiers work on that principle.
    Ventilation is a useless way to try reduce condensatioin. If that worked ,then the area with the most ventilation would have the least condensation. The insides of my vent pipes have the most condensation anywhere, yet have the most ventilation..
     
  12. capt littlelegs
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    Location: England

    capt littlelegs New Member

    Good underfloor insulation is essential of course. The way we ventilate the bilge is to pipe outside air to the bilge then provide part or all heater combustion air directly from the bilge, this also helps keep the cabin air ventilated and dryer. It won't stop any bilge condensation but it helps dry it out.
     
  13. Brent Swain
    Joined: Mar 2002
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    Location: British Columbia

    Brent Swain Member

    I know a guy who fed air to his oil stove from behind al the interconnected lockers, to draw air thru them. Worked well.
     
  14. M&M Ovenden
    Joined: Jan 2006
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    Location: Ottawa

    M&M Ovenden Senior Member

    I'm into the insulation search nightmare. I'm actually sold to armaflex but can't help looking around a bit more. This product has been presented to me http://www.isover-ultimate.com/ .

    I haven't looked it threw to much but first impression is, I don't like it. Seems to be a fibrous material hence not closed cell.

    I'd be interested by opinions on this stuff. It seems more like a product to be used on ships rather than pleasure boat and am quite surprised it was offered to me as a better alternative to Armaflex (salesman). Apparently all boat yards in Quebec use this :confused: . ...I'm in Ontario, guess I don't have to follow than :) .

    Cheers,
    Murielle
     

  15. apex1

    apex1 Guest

    It is mineral wool Murielle.

    A proven and valid solution for our "big brothers", not the first choice for us.

    Being fire resistant is their main advantage, a very important point with cruise ships.

    A peculiar irony, these advanced mineral wool materials once were developed by my father.

    Stick to the (expensive) Armacell range.

    Regards
    Richard
     
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