Floatation Foam

Discussion in 'Materials' started by member74761, Sep 5, 2021.

  1. member74761
    Joined: Aug 2021
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    member74761 Junior Member

    Hello All.

    I'm trying to plan a little ahead, make the right choices.
    On the subject of pour foam.
    It seems 1 thing for sure, its going to eventually turn to a wet sponge it seems.
    I have turned the inet. upside down last few weeks and seems to be the same.
    So is it worth while or not, seems if you gouged a hole in the hull, even wet foam would be better than nothing.
    But holding constant moisture in a boat is not the best thoughts. When you are thinking about your boat.
    So how long is the newer pour foams expected to last. any ideas
    I just know every boat I have tore into, older boats have had sopping wet foam.
    Thanks in advance.
     
  2. jehardiman
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    jehardiman Senior Member

    Ok, you can generally say there are three types of "pour foams". Open cell, closed cell, and syntactic. From a practical sense, you can get both closed cell and open cell foam in all different stiffness. There are several ways to do this, both for single and two part mixtures. Compare an open cell camping mat designed to be self inflating to a sheet of rigid pvc; very different stiffness but both open cell.

    What most people consider when you use the term "pour foam" are open cell foams. These "foams" are usually two part and work by generating gas bubbles in a matrix that hardens. There is no control to ensure that the cell wall between each bubble does not thin too much and break. These foams tend to be brittle and offer little resistance to water penetration but are commonly used in skinned composite construction. They will last until they are structurally compromised (i.e. fail internally) or a water path is provided.

    Closed cell foams on the other hand are formulated and manufactured to maintain the wall between each gas bubble. Generally most "home use" closed cell mixtures tend to be more flexible (because you only get to use atmospheric pressure to control bubble expansion) but some will harden to be sufficiently structural. Again these closed cell foams will last until they structurally fail but are much more resistant to general water intrusion.

    Finally there are syntactic "pour foams". Syntactics have no "bubbles" but rather have lightweight hollow spheres totally encased in a rigid matrix. However, syntactics cannot be worked after forming, the must be formed to net shape. Additionally, because the exotherm of the matrix is not expanding the "bubbles" the thickness and shape of the pour can be limited. These foams generally have a much higher resistance to water pressure, but tend to be brittle. Also, they are much harder to work and can be significantly heavier in thin sections.
     
  3. missinginaction
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    missinginaction Senior Member

    I think you've answered your own question. You'll probably get differing opinions but for me one of the most important things about keeping a boat mildew/mold free and comfortable is ventilation. When I restored my small dual station cruiser a decade ago I went out of my way to make certain that the entire boat, even areas under the cabin sole were open to each other.

    You're probably thinking "What might happen if he holed her?" Well, first I watch where I'm going and if unfamiliar with an area I proceed slowly. Holing is unlikely. I've been boating for 50 years and never holed anything.

    I installed two large bilge pumps when I did the rebuild. I added a Groco service adapter to my raw water seacock. This turns my engine raw water pump into a bilge pump in an emergency and can easily pump 30 gallons per minute out of the bilge and out the exhaust. I keep a dry bilge and have never had an issue except for once when I carelessly did not secure the quick release plug into the service adapter on the seacock. We dropped the boat in and slowly brought her around to her slip. Probably took 15 minutes at least. As we were tying her up I said "I'm hearing water, where is that noise coming from?" "It's one of your bilge pumps" a friend replied.

    Knowing that wasn't right I opened the access to the engine compartment to investigate and found water gushing in through the service adapter port. I had a fair amount of water in the bilge but the level was so low that even after 15 minutes or so the second pump never activated.

    Moral of the story....Pay attention to what you're doing and install more bilge pumping capacity than you figure you'll need. As for the foam, I'd forget about it unless you can't provide enough bilge pumping capacity.

    MIA
     
  4. member74761
    Joined: Aug 2021
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    member74761 Junior Member

    Thanks for the reply.

    I'm referring to closed cell 2 part and particularly, I think the brand is true composites.
    I have 4 gallons of the stuff now and poured a few very small tests,
    What I have found is its very hard if truly well mixed.
    I did a different test run in a plastic drink bottle, I poured equal amounts in this bottle unmixed, and proceeded to attempt to mix in said bottle, rolling, swirling and such.
    Well that didn't turn out so well, oh it foamed and boiled out, but it never did set like the others, yes the bottle was dry. it just didn't mix well enough. is what I suspect.
    2 days later it was soft and stretchy.
    I'm attempting mess with this stuff enough to know the do's, don'ts. and have an edge before I blunder on bigger pours.
    Probably need to pour 6-8 gallons when it's all said.
    I'm also pondering adding some thick walled drink bottles in the cavities, true unbreakable air pockets that won't allow water in unless they condensated.
    not typical soda bottles they are too thin for my liking. some of the energy drinks are fairly thick and the formed/moulded in sides make them difficult to distort with your hands.
    now it would take several 100's but this would cut down on the foam and if the foam did sponge up even that would be lessor with the larger air pockets displacing the foam.
    I understand this seems,. Rigged. but the hundreds of dollars I spend for foam to just wait to take on water is not very appealing to me either.
    I'm trying to figure a way to have a safety net, for the net.

    thanks
     
  5. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Polystyrene blocks are pretty good at not becoming water saturated, you can paint them with acrylic latex paint to give a measure of protection, especially from fuel, which will destroy it. It depends on the application whether polystyrene is suitable. Another option on polyethylene flexible foam, which again resists water saturation well, and can be squeezed into awkward spaces. It is not that cheap though. A further possibility is plastic drink bottles packed into the areas you have selected for buoyancy. It isn't too hard to work out how much volume you are getting by the capacity of the bottles. Pour foam is better left uncut, let it rise like a loaf of bread, don't cut it afterward, that way you get a better chance of less water intrusion
     
  6. member74761
    Joined: Aug 2021
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    member74761 Junior Member


    I'm new to boating,
    Paying attention is part of why I'm here. I have read of many experienced boaters hitting or running into debris slightly submerged.
    As you can tell, I'm on the fence about foam, however, I don't see me, Not putting foam back in.
    The value it adds to structure for support and sound is almost enough. in itself.
    My boat was almost solid with foam, just the rear half of bilge was un-foamed. forward under floor, solid. gunnels solid front to rear. but it was all wet.
    I pondered, just pouring the whole thing solid, keep all the water out. yes it may roll like a dead whale, but it'd still be floating if the worst were to happen. you can recover a floating vessel.
    Pumps are fine, I get all that. my thing on pumps they can fail, batteries go dead, fuses blow. and yes I will have at least 2, one elevated to avoid sludge/clogging. the best solution is keep water out.
    hopefully none of this happens, I try to prepare or have the bases covered before the play, I guess is a good way to put it.

    thanks
     
  7. Mr Efficiency
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    Mr Efficiency Senior Member

    I know a fella that hit a floating log at night in a 6 metre GRP power cat, he was travelling at around 20-25 knots, no more. It was a solidly built boat, but both hulls were badly damaged over quite a length of the boat. You could put your arm in some of the rents. But the boat had both sides packed with large polystyrene blocks. He was able to motor back slowly to land. Otherwise, a fraught situation, it is possible the boat may not have sunk, without the foam, but it would have been necessary to promptly block the freeing ports on the deck, easier said than done, and there may have been other ways for water to enter as well. Point is, buoyancy chambers would not have worked, the damage was so extensive, it greatly surprised me how much for a boat travelling at modest speed, and he would have been going no faster, the boat was a bit underpowered really. He was lucky to have a version of that boat that had the foam blocks, many did not.
     
  8. member74761
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    member74761 Junior Member

    This is the sort of story that makes me keep foam on board.
    When you have /arm sized tears, holes/ I feel several pumps would be overcome or tire soon, my luck the damn fuses would blow.
    Even the wet foam I removed was heavier than I desired, however even with it I could have hit a stump and made it back I feel.
    The foam even wet has a better safety factor, than no or 0 foam.
    The thing that bugs me is the moisture it held/holds against my stringers. That I am now replacing.
    Along those lines, I'm thinking of wrapping my stringers with pink/green closed cell board, then pouring foam..
    This should help protect my stringers.
    But again I don't know how long it takes and what abuse is required to cause pour foam to take on water or fail.
    I am for a lack of better words starting with a now new, or better than new boat.
    That I have not had before, I always had a boat after someone else enjoyed it first.
    So I'm starting out fresh, after I finish this build.

    thanls
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    There is plenty of prejudice against pouring foam, because of the water intrusion aspect, but that can be guarded against. I dare say some of those people who dismissed foam buoyancy are in Davey Jones' locker, and no longer complaining about it.
     
  10. member74761
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    member74761 Junior Member

    but that can be guarded against.

    Ok,
    heres what i think i know.
    don't cut it or drill or run screws in it. if you do seal with epoxy.
    don't expose it to water for long lengths of time. especially freezing.

    I'm all ears. or maybe eyes.
    what other precautions are in order.

    thanks
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    As I mentioned, don't cut the expanded foam "skin". Don't allow water to be washing around it, or having condensation form, by having voids in the compartment you have installed it. Just simple common sense really. If you give the boat a fearful thrashing, the cell structure could break down somewhat, but I would doubt to a marked degree, ahead of the crew being disabled. You could even expand it inside good quality plastic garbage bags, and weld them sealed with a cheap plastic welder. Any buoyancy material is better than reliance on sealed voids, my view is you pack with foam (keeping in mind where it should be installed such that a swamped boat does not become unstable), or you carry a self-inflating life raft, and the latter is not practical in small boats.
     
  12. Ike
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    Ike Senior Member

    There is "another way". Make the compartment you are pouring the foam into, water tight. Use PVC sheet plastic to line the compartment Pour the foam, wait till it finishes foaming. Then seal the top with the plastic. Of course this means having an open compartment to put the foam in. If you have already built the boat, that may be difficult. But if you haven't reached that stage yet, give it a thought and figure out how to do it. This is also how polystyrene foams are used. They are bagged and sealed up so that caustic liquids such as gasoline, oil, cleaners, etc., can't get to them.
     
  13. member74761
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    member74761 Junior Member


    Thats a great idea for water intrusion.
    However, it breaks the adhesion of the foam to the hull. like a nut in a shell.
    I like the rigity the foam adds or structure when it adheres.
    It's hard to pocket a 19' gunnel. I have larger areas to pour, some of that will be under floor after ply is set and epoxied.
    So I have some choices to ponder.
    You would think, with all the chemists, science, technology, a better formula would be available 60 years later. this is a well known problem.

    thanks
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    If the foam expands with restriction, it ends up denser and less friable, and less likely to absorb water, and also offer structural benefits. At a cost in $ and extra weight though. But it is a matter of nice judgement, as to how much you restrict it, unless there is a degree of "relief" available, it can bust or bulge structures.
     
    jehardiman and member74761 like this.

  15. member74761
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    member74761 Junior Member

    Ok, thanks to all the replies I have been thinking on different ways to keep moisture away from stringers and still use pour foam.
    So heres the idea, What do you all think..
    Wrap the finished stringers in the pink "stuff" I could use 1" or 2" the 2" is actually cheaper per say at 18$ board vrs 12$ for 1"
    and when I say wrapped, That's both sides and top, yes time consuming, Maybe spot glue just hold while fabbing and pour to allow water to flow out should it get in.
    So basically not trapping water against stringers, leaving it sorta open.
    Then pour the rest of the boat.
    And since there is no straight forward answer as to how long the new formula pour foam will last. and so may variables pertaining to care and storage or neglect.
    This is my solution. as a structural safety net for stringers.

    And did I read the pink stuff is 4-5 pound density ? so stronger or better for impact than 2# pour.

    Thanks again.
     
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