Wet Flotation Foam

Discussion in 'Boat Yard Basics' started by Bumper, Feb 12, 2010.

  1. Bumper

    Bumper I Love microskiff.com!

    Just looking for some opinions, I am always reading about digging wet, soggy foam out, making whatever repairs and then putting the same foam back into the boat. This reminds me of a definition of Insanity: doing the same thing over and over and expecting a different result. What keeps the new foam from becoming a soggy mess all over again? Even old Whalers get soggy and they are put together pretty good initially, which just shows that water can and will get in somehow, someday. What else can we use, recycled water bottles.....?
  2. Brett

    Brett > PRO STAFF <

    I did it for peanuts...


    Polystyrene peanuts...20 cubic feet from the UPS store

    This link and the next 12 images in the album explain the how and why.


  3. ucfscaper

    ucfscaper Well-Known Member

    Not to derail, it keeps in tiding with the question;
    What benifit is gained by flotation foam if the air space is pretty much sealed. (I understand it floats the boat in the event of a hull breach) Color me stupid...or just set me straight. Does installed flotation 'stuff' provide any additional boyancy over trapped air??
    When I refurbished my skiff I removed about 100 pounds of wet foam from two of the three locations. The ninny that owned the boat prior to me installed seat bases that allowed water to intrude. The third location was dry as a bone. I simply glassed over the holes and called it done. Maybe I'm a ninny too......
    Thanks, Tim
  4. Brett

    Brett > PRO STAFF <

    The purpose of foam filled chambers is to ensure level floatation.
    In case of hull impact, or cracking due to hull flex, the foam
    guarantees bouyancy that a leaking air chamber can't.
  5. topnative2

    topnative2 Well-Known Member

    I don't think the peanuts will provide the benefits of the poured foam----such as adding rigidity/reinforcement and ,god forbid you puncture the hull the water will diplace the p's-- w/ the foam that would not occur--- i bet it would not meet uscg standards--- alot of time and love invested.................
    just a thought!
  6. Brett

    Brett > PRO STAFF <

    from page 42 of the backyard builders regulations


    Before building I called and asked, the officer I talked to said as a home builder
    that the polystyrene peanuts were fine. Technically I could get away with just a sealed chamber.
    The idea is, in the event of a capsize or swamping, the hull remains afloat.
    In the event of a collision with another vessel, my priorities will be different.
    I won't be worried about my microskiff, I'll be worried about injuries.
    Poured foam creates one other problem, it never stops expanding.
    It can actually distort the hull due to the pressure it exerts.
    And remember, a wood built boat floats because it's built of wood.

  7. topnative2

    topnative2 Well-Known Member

    This is fun!!!!!!!!!!!!!!!!!
    Ya got me on the peanuts now I know what they are made of :D
    air chambers are allowed if the chamber is not part of the hull(tanks..for the link) but what about a pressur test?
    O.K.--ref collisions I do not believe the argument holds water-lets say u whack a marker w/ the bow or u get run the slap over the floatation "dissappears" ur boat will go stern down in a flash--never mind the absorbtion of the crash---u could use foam blocks and get the benefit I am proposing--being injured I would be looking for something floating to hang on to
    stronger is always better=safer

    gettin a cold one >>>>ur turn [smiley=1-beer-german.gif]
  8. beyondhelp

    beyondhelp Well-Known Member

    I used blue foam board after spending a really long time hunting for the "best" solution. In my case, the solution was a result of factoring all of the variables and making a logical decision in my situation. I've heard of truck tubes, soda bottles, packing peanuts, poured foam etc... the blue styrafoam board I used is dense 1/2" or so and was easy to cut and if it absorbs water I'll be amazed. I used foil tape to prevent the resin from running down into the foam and pl adhesive to bind the deck boards to the stringers prior to glassing over them. Hope I never have to test their flotation.

  9. Brett

    Brett > PRO STAFF <

    Ooooooow....that one stank! Nice try though... ;)

    Wood boat, eh? Even after a collision the wood floats! Hang on to that... ;D  (waitin' for your return...)

    Still, finding the foam to fit your project is part of the fun.
    I searched to find the best bang for my buck. Ergo...packing peanuts.
    Elsewhere, foam blocks are a local product, my town...not.

    beyond... I looked at the foam panels, great use of a building material in a boat project.
    I've been playing with the idea of a foam panel backed plywood hull.
    It would eliminate the need for space eating bouyancy chambers.
  10. topnative2

    topnative2 Well-Known Member

    yes wood floats by itself----are we assuming then that the only weight in/on the boat would be in the correct ratio to wood to maintain bouyancy....but alas there is an engine----and our fat butts blowing bubbles
    ALSO, are u maintaining the position that poured foam or blocks do not add absobtion of impact enery
    or structual strenth to the boat

    How Does that grab you [smiley=dancing-smilie.gif]

    I await w/ great antisipation [smiley=1-sobored.gif]

    (looking out the window at 2+ in. of snow)
  11. topnative2

    topnative2 Well-Known Member

    Now that is a great job w/ the foam! [smiley=1-beer.gif]
  12. Brett

    Brett > PRO STAFF <

    Wood floats. After impact who knows what will end up where.
    Odds are the hull will be torn apart, the phrase "parts 'n pieces" comes to mind.
    On a small skiff the injuries from a collision at planing speeds
    will be greater to the people on board than the hull. (I'm an optimist, can you tell?)
    Only takes 8 lbs of bouyancy to keep a human afloat.
    Cooler, life jacket, boat cushions...blah, blah, blah.
    And anything, between you and the oncoming object, is better than nothing!
    But all this is of no importance, it's snowing and you're not out in the shop building your own boat?

  13. topnative2

    topnative2 Well-Known Member


              peanut v. block of foam


    Does color matter :D

    We be done!!!!!!!!!!!!!!!!!!

    I enjoyed that!

    Next>>>>>> ford or Government motors
  14. TomFL

    TomFL Well-Known Member

    I don't know what's better, foam or peanuts but I can tell you the foam in every gheenoe I've worked on was soaked to the bone. To the point of it adding excessive weight to the gheenoe.

    So I see the point of wanting to try to avoid that if possible.

    But, I do like the idea of adding structural integrity to such a thin-hulled craft. In the classic I'm gutting now, I'm adding a flat floor with 4lb foam between it and the hull. I think it will not only add structural strength, but also impact resistance, and, God forbid, possibly seal off anything that might possibly otherwise breech the hull when things go bump in the middle of the marsh at night.

    The trick, I believe, is to seal it well. Really well. And never compromise that seal with a screw hole or anything!

  15. topnative2

    topnative2 Well-Known Member

    I wonder can you glass over the blue stuff like at HD.

    What other water proof foam is out there?

    We need the man for this one>Brett
  16. Bumper

    Bumper I Love microskiff.com!

    I appreciate all the info coming out on this, I had a piece of foil backed foam board (box store insulation board, less than $14.00 a 4x8 sheet) here on the tugboat, it seems to be closed cell, and cut a small piece and have been soaking it in a cup of water for the last week. I peeled the backing off both sides first. I can't see any water absorption yet. I was thinking of using it in a underdeck/gunnel laminate fashion such as Brett suggested. Get some flotation and maybe even add to the stiffness. It is fairly brittle, definitely not Klegecell, but I want to test a small piece with some epoxy to see if it dissolves or anything when I get back ashore next week. I will post results.
  17. Brett

    Brett > PRO STAFF <

    Previous build


    looks like the polystyrene panels from the home improvement store...

    polyester resin will dissolve polystyrene foam

    epoxy can be used on both polystyrene foam and polyurethane foam.

    foam panel types:

  18. DuckNut

    DuckNut Brandon, FL

    The two part foam will absorb water and act as a structure in the hull, but even though it is wet it will still float. If you are not concerned with structural aspects the type of foam used for pool noodles is the best. As Brett indicated most anything can be used. Many people have used the blue and pink foams with success for their intended purpose.

    The 2 part expanding foam will continue to expand for quite sometime and can cause stress and even damage to a small boat. However, after the off-gasing ends the foam will actually shrink and start to break down and that is when it will start to absorb water.
  19. ucfscaper

    ucfscaper Well-Known Member

    Happy Valentines Day everyone!

    What I get from the discussion.
    Air tight spaces are equal to foam filled spaces, actually better because you don't have the weight of the foam. (I know its not alot)
    Given, you don't worry about hull rupture or need to additional structural support afforeded by pour in foam.
    When I retrofitted my skiff, I removed the offending wet stuff and added a jack plate (12 lbs) that set my motor back 5.5 inches. Also added a poling platform, weight less than 30#. I figured the reduction of 100# of wet form would offset the set back and the weight of the platform, boy howdy I was wrong.
    Small skiff owners beware, set back equals alot of weight. I lost about 3 inches of free board at the transom, only had about six to start with. Reverse gear results in wash over even at the lowest of idle and slowing down from WOT if abrupt would swamp me. This creates a safety issue, can't stop fast....not a good situation for everyone while running the Econ.
    Any mathmaticians out there? What does each inch of set back equal, in #'s, or is that continent upon the displacment of the hull?
    BTW, the speed gain by adding the jack plate is almost unbeleavable, 7 mph by my handheld GPS. Now I am left to concider removing the jplate and building the transome 'up' a bit. (with the JP my motor is set 5 inches higher than before)
    Thanks for all the great information.
  20. Frank_Sebastian

    Frank_Sebastian Well-Known Member

    As has been mentioned before the foam "can" be structural. As in the Whaler the foam is a 4#per ft³ and quite strong. Many other boats take advantage of the fact "if you have to have it, why not use it". The Carolina Skiff is a puzzle though as the foam elements are pre-cast and run transversly (athwartship) to the hull? What I have done when I had to replace the foam was use heavy plastic bags which could be blown up by a reverse hose vacuum and the 2 part closed cell foam poured inside. The first I ever did was a 19' Angler. I had the foam on every tool, piece of clothing and for the most part the inside of my shop. I vowed never to do it again, but I did and got a fellow to help me that knew how. For a smaller hull a heavy vinyl or shower pan liner type material will do just fine. Leave it long enough on each side to cover the middle and glue it before putting the deck on.

    Best regards,