Water trapped in hull

Discussion in 'Boat Design' started by kaf69, Jan 8, 2013.

  1. kaf69
    Joined: Jan 2013
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    Location: Mandurah WA

    kaf69 New Member

    Hi all
    I am new to the forum so please excuse me if I ask questions that have been asked and answered.
    I am busy rebuilding my 1979 17 foot Chives Pursuit, while using it to fish offshore.
    The hull is leaking a small amount of water (about 3 litres per trip). This is what comes out of the hull drain plug at the end of a trip.
    This is my problem; some water gets stuck on the port side of the hull and has accumalated over time, as it does not drain out.
    Now the boat always leans to port when under power due to the weight.
    My question is
    As far as I understand, the hull is divided into compartments by”stringers”, these compartments are filled with floatation foam.
    Are these compartments connected via drain “tubes” so that water can drain? Or are they sealed compartments? As no matter what I try, I cannot get this “trapped” water out of the hull.
     
  2. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Most foam bilge boats I see dont have limber holes between foamed compartments.

    Water usaully enters the foam compatment thru the cockpit sole via poorly installed equipment or chase tubes for cables.

    The only way to find out is to cut an inspection hatch , then cover and formulate a battle plan.
     
  3. SamSam
    Joined: Feb 2005
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    Location: Coastal Georgia

    SamSam Senior Member

    In theory, limber holes are drilled at the bottom of each partition so they will all drain to the bilge and out the transom or bilge pump.

    It was hardly ever done correctly that long ago and maybe still not done right. They were seldom lined or glassed to where water couldn't get at the stringers and rot them. The holes themselves were usually too small so they were easily clogged, or hardened glass fibers left across the openings that trapped trash and clogged them up. Sometimes the holes in the stringers and partitions were glassed right over and never re-opened up.

    All kinds of sawdust, wood chunks, trash, tools, tape measures etc are left in there before the deck is installed. Out of sight, out of mind, out the door. I found a walking cane entombed in the bilge on one rebuild.

    You might try tapping around on the deck to try and figure out where the partitions are, take a guess about where the water is trapped and then install one of these

    [​IMG]
    http://www.downwindmarine.com/RWO-Screw-Out-Inspection-Covers-with-Seals-p-90891141.html

    so you can see what's down there. If it's waterlogged foam, you'll have to dig it out.

    Oh, and find the leak and fix that.

    If you have a shop vac that you can reverse the flow, you might try putting that up to the drain plug hole and blowing some air/putting some pressure into the bilge. Do that and release, do it again etc, you might dislodge trash in a limber hole or something so the water can drain. It might help you find the leak also. Be careful about too much pressure though. I doubt a vac could make enough, but an air compressor could cause problems. If you hear any untoward sounds, cease and desist.
     
  4. Frosty

    Frosty Previous Member

    Thats what you get with foam. In the old days a rope would travel all through the drain holes and could be pulled back and forth to clear debris from drainage.

    That before Sh1tty foam bilges came along.
     
  5. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    > If you have a shop vac that you can reverse the flow

    I have used this method + soapy water to find small leaks (you can hear the bigger ones). But if your problem compartment is completely isolated, then you need to add a hole to pressurize it (and empty it).
     
  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Most boats built since the early 70's don't have limbers and worse, the liner hasn't any way of letting accumulated moisture get out, between it and hull shell. Boats of that era also commonly employed open cell foam, which just wicks up moisture, so even if there is a drain, it doesn't get out and remains stuck between the hull shell and the liner, which rots all the wooden elements there as well.

    Your '79 likely has stringer and sole issues as too, as a result of this production oversight. The usual course is to remove the sole, dig out the foam, which will weigh ten times what it did when installed, refoam with closed cell or just seal the compartments (with limbers added) and install a drain aft, to let moisture out.

    No deck plate (pictured above) is going to help this situation. The opening is only 6" in diameter and you'll make a career out of trying to remove foam through a 6" hole. It's also very likely you're hull has several partitioned areas under the sole, all with foam and all trapping moisture, so you'll need a dozen or so deck plates.

    I make this repair fairly regularly and my first tool is a circular saw, set to the depth of the sole. I cut out the sole with a 3" - 4" flange along the edges and set this big piece aside, for reuse. With the sole removed, it's simple to hack out the foam. It cuts easily and a hand saw works best. Once the bulk of the foam is out, clean up the areas with a sander/grinder, insuring a clean surface for the next steps. In most cases the stringers are also shot, but if not, the area needs to be well coated and possably some cloth, to seal up the substructure. Cut generous limbers and make provisions for a sump/well or other way to install a drain, typically under the splash well.

    With all this done, you can reinstall the sole, if it's salvageable. Grind the edges of the flange and sole piece(s) and bond in with fabric and filler. Paint or gel coat to finish.
     
  7. jonr
    Joined: Sep 2008
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    Location: Great Lakes

    jonr Senior Member

    With enough blown in warm dry air, one can eventually dry out open cell foam (it's vapor permeable). I have no idea if this is practical to do in a case like this, but a 4" deck plate is easy and around here we have months of downtime.
     
  8. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Pulling vacuum is a better method, but neither is especially practical.
     
  9. whitepointer23

    whitepointer23 Previous Member

    It is a chivers pursuit built by laurie chivers it does not have any foam bouyancy. Just glassed in air pockets under the floor. Look for drill holes. I bet there is 1 somewhere and water is pooling in 1 of the pockets. If you have an under floor fuel tank pull that out and fix it in better. They were a pretty rough install from the factory.
     
  10. watchkeeper

    watchkeeper Previous Member

    Might be worth while lifting the boat out (if it stays in) and checking the hull for any splits and any thru hull fittings for lack of seal.

    I have drilled pilot holes in bilge and keel area in RFG hulls to find and drain trapped water. Drilled holes are easy to replug with epoxy 2pk and a plug drill core and the entry countersunk to fill/fair with epozy filler.
     
  11. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    Over time that water may have rotted stringers, etc.. Even if you get the water out of air chambers, it's very likely that there's been some damage. How much depends on how long the water's been in there.
     
  12. kaf69
    Joined: Jan 2013
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    Location: Mandurah WA

    kaf69 New Member

    Hi whitepointer23
    Yes you are correct, it is a pursuit built by laurie chivers, but it does have foam bouyancy in the cells, as I have cut in one deck plate to have a look.
    Do you know if these hulls had "limbers" ? or were they sealed cells?
    What are the "Drill holes" that you have mentioned, as I suspect it is only one or two cell that are retaining water.
     
  13. kaf69
    Joined: Jan 2013
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    Location: Mandurah WA

    kaf69 New Member

    Thanks PAR

    Fantastic advice, but could you answer a few more questions for me as this is my first rebuild.
    Is closed cell foam somthing that I could install? Would the Foam be "Pumped" in after I have re installed the sole?
    When cutting out the sole with a "3" - 4" flange" is the rest of the sole not screw down to the stringers? Or is it only resting on the stringers and glassed to the sides of the hull shell? Can you successfully apply gel coat by brush or spray with out "moulding " it?
     

  14. whitepointer23

    whitepointer23 Previous Member

    Sorry. I had a chivers thunderbird and that had no foam in it just air chambers. I doubt if there are limber holes in each cell because they are supposed to be fully sealed . Have a good look for drill holes that may be lettinv water in. It is an old boat and they tend to end up with holes here and there when owners do different things over the years.
     
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