water logged floatation problems

Discussion in 'Boatbuilding' started by Guest, Feb 23, 2003.

    Joined: Feb 2005
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    Location: ETOWN, KY.

    MATTRESS GUY Junior Member

    I Had A 14' Aluminum Jon Boat And I Cut Foam And Put Between The Supports Of The Hull, I Then Screwed Marine Plywood On Top And Then Put Outdoor Carpet, 4 Yrs Later The Plywood Was Warp And Bowing Up All Over, So I Decided To Replace Just The Plywood, And When I Removed The Old Plywood, I Picked Up A Piece Of The Foam And It Was Sooo Heavy, But I Could Hold It For A While And No Water Would Come Out Of The Foam,,somehow The Water Was Trapped Inside The Foam And Couldnt Escape..now I Have A 24' Aluminum Jon Boat That Has A Factory Aluminum Floor With Foam In Between, And I Know That The Foam Is Soaked.i Dont Know What To Do, I Just Wonder If That Hotvac Will Dry That Foam Out With Out Cutting My Boat All To Pieces..if That Really Does Work , I Could Do That Every Couple Of Years..it Just Seems Like My Boat Is So Heavy..i Commercial Fish In Ky..so Weight Is Very Important To Me...
  2. rob kirk
    Joined: Jan 2005
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    Location: texas

    rob kirk New Member

    there is no way i would get in that boat & shower down on the throttle with out
    fixen the floor & first of all the transom for sell signs are cheap
  3. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    The foam used in the 60's 70' and 80's era boats wasn't closed cell, no amount of time in a baking oven will remove the moisture from the foam. I've seen 17' powerboats dragging several hundred pounds of water around with them in soaked foam. You can prop up the boat, drill holes, bake it, use fancy shop vacs, whatever, but the water will remain. The only way to insure it's removal is to get the foam out. It cuts easily, but is wedged into places where getting at it will require some effort and thought.

    Poured in closed cell polyurethane is the way to go, regardless of what car painters have to say. It doesn't hold water, it can't and it conforms to the hull shape, gets into every corner so there will be no voids (which will fill with water) It can be purchased in different densities so that you can use it as structural support or pure floatation.

    You don't have to have a leak to gain moisture in this old type of foam, folks. The condensation that naturally occurs, collecting on the underside and inside of a hull liner or deck support structure, will run down to the lowest point it can, where it will pool, or in these cases be absorbed by the sponge like material used as floatation. All boats, regardless of construction materials will have this happen to some degree. Wooden boats have these spaces well ventilated to allow the water to evaporate out of the space, but a lot of 'glass hulls are sealed up tight below decks and liners, not even having limber or drain holes trapping the moisture.

    Painacar, your boat needs major structural repair, the transom, some stringers and floor will need be replaced. I know you don't want to do the work, but you could well be watching you engine swimming around under the back of your boat, attached by it's control cables after it's ripped itself off the very weakened transom. I've seen this happen and it's funny to watch if it's not your boat. The boat usually sinks pretty quickly missing the large chunks of transom the engine will tear out with it and having floatation already filled with water.

    Mattress Guy and everyone interested, there is no magic goo in a can or special machine that will fix these issues (I know it sucks) I dig this crap out of boats a few times a year, trust me, if there was a way, I'd be using it.

    The real problem is not only are you carrying the water around in your floatation, but it rots out the wooden support structure built into the boat. This is where the real damage gets costly. Transoms, stringers, engine beds and support pieces have to be renewed. Yes, you can replace the wood with other materials (foam) but it requires some engineering and a lot more 'glass work, which most amateurs don't really like to do. Wood is used because it self supporting (unlike foam which relies on the 'glass skin to provide all it's strength) easy to work into shape, easy to install, takes adhesives well and if the structure is well designed, long lived.

    There's a reason these boats are considered disposable after so many years and also why they are so inexpensive when new. They are built with a limited life span in mind, unless stored in a climate controlled garage and used rarely, they literally break down from the flaws (like no internal drain holes) designed into the structure. Sure a much better designed craft could be built, but they'd cost twice as much and they'd sell less boats. So, the manufactures build lots of reasonably inexpensive boats that will need to go to the land fill, before your new born son can enjoy it during his high school years.

    Now when I do rebuild a sole support structure, stringers or similar I do make the effort of installing limber holes and drains so the water can come aft to the transom plug. Once the deck is off, it becomes pretty obvious where the water was trapped and why. Fixing that isn't a lot of trouble so the repair will live longer then the boat was intended to survive. The question you have to ask yourself is the same one the boat manufacture executives have asked each other. How much more effort are we to put into this inexpensive boat?
  4. IF you decide to start repairs ---Remember that there are built in spaces that MUST be kept the same number of inches apart . Before you start, take the heavy parts out of the boat. Eng., stern drive, gear, and anything else. This will stop any present distortion and help the deck- stringers- floor and hull bottom to return to as much as possible --to the original shape . DO NOT cut out big areas. Do 1 stringer-- than the other-- etc. If the floor feels springy , TAKE a measurement between it and the hull bottom , before pulling all the foam out. You may have to put in temporary foam blocks to support it during repairs. THINK AHEAD and you can remove and repair. If you smell fumes or get light headed--- get out of there FAST.------ Home Depot sells 10' lenghts of E M T electrical tubing 1/2" size. Buy 1. Cut with hacksaw, bend by hand into great hooks to rip and tear out the foam in a place you do not need to butcher up. No engineer, just time and patience. :)
  5. Dallas_B_
    Joined: May 2004
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    Location: Boerne Texas

    Dallas_B_ Dallas B


    My 25' bay boat had water log foam in it, So I rip out the old fiberglass CHOP out all the foam replaced old wood and went back with A&B mix foam. When you mix this up ...and if its hot outside work real fast. After it drys in about hour or less...just trim it flat...or put your new wood down and drill a few holes in the wood and pour in.
  6. Herman
    Joined: Oct 2004
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    Location: The Netherlands

    Herman Senior Member

    Polyurethane foam is closed cell. At least, for liquid water. Cell walls however are thin, and water vapour can transfer into the cells. This vapour slowly condenses. See what happens? after a while, the foam is filled with water.

    In the first place, water, not in liquid form or as a vapour, should be allowed to get in contact with the foam. Ever. This is the only way to keep the foam dry, and the customer happy.

    Personally I like boats with a number of hollow compartments better than boats filled with foam. Hollow compartments can easily be drained. Foam filled compartments can not.

  7. The correct place for all flotation foam is way above the water line. That way the foam is never swiming in water. It will also keep your boat upright in most floodings. If the boat is overloaded and over weight by the designer, he is forced to put foam below the water line.
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