water in bilge - fact of life on keel stepped mast?

Discussion in 'Sailboats' started by mattplowman, Apr 1, 2008.

  1. mattplowman
    Joined: Apr 2007
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    mattplowman Junior Member

    i am looking at buying a boat after many years of dreaming - i am now doing what i have been told is a must - i am looking at many many different boats to get a feel for what is out there

    i saw a great kiwi designed and built boat yesterday but there was water in the bilge around the mast area - not a huge amount but enough to notice.

    the broker said that small amounts of wtare in the bilge around the mast on keel stepped masts is a fact of life?? is this true?

    Thanks
    Matt
     
  2. alan white
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    alan white Senior Member

    Good salesman. Actually, the mast is not necessarily in the lowest part of the bilge. No doubt that boat had the mast positioned at the lowest point.
    Deck stepped masts almost invariably exert exactly the same compression loads on keels as do keel-stepped masts, through a post that is positioned between deck and keel. Only lateral loads, which are minor on stayed rigs, are present with a keel-stepped mast. Therefore the salesman or broker was talking nonsense.
    It is never wise to listen to a broker or an owner when something seems amiss.
    You will pay for that mistake for many years. Best to nod when they speak but pay a surveyor, one who isn't related to the owner or the broker.

    Alan
     
  3. Roly
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    Roly Senior Member

    Just a thought Alan, perhaps the broker was talking about water coming down
    the mast on a keel stepped,from sheeves at masthead and various apertures that are hard (impossible ?) to seal? I have had two keelsteppers and both leaked into the bilge when it rained hard. Surely you can stop that on a deck stepped?
     
  4. RHough
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    RHough Retro Dude

    Is the water salt or fresh?

    Fresh can be normal. Rain, condensation etc.

    Salt, well, shouldn't have much salt water in the bilge.

    A proper mast step will allow some water in the bilge before the mast butt is in the bilge water. If there is more water than that, inspect the mast VERY carefully. Clean out the bilge, pull the floor board up and survey the area completely. Corroded mast butts can be expensive to repair. If the water in the bottom of the mast froze, the mast can be cracked ... worth a close look.
     
  5. PAR
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    PAR Yacht Designer/Builder

    A berthed or moored vessel will always have water in the bilge. This assumes the pump is only able to remove all but the last inch of water depth, before they suck air and lose their prime. Water will enter through several possible routes and extruded alloy spars, particularly those with some internal elements (wire chases, halyards, etc.), are famous for it.

    The step should position the spar in such a way, as to permit the accumulated moisture to drain away from the mast, into the bilge. If the step and the mast heel must live under the low bilge water line, corrosion will be inevitable.

    The pump can't get all the water out, but good yacht design places the pump, not only at the lowest point of the hull, but also in a shallow, confined well so that only a pint or so of water remains, but the bulk of the bilge is dry.
     
  6. alan white
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    alan white Senior Member

    You are right. That would, on second thought, make more sense. I had some idea from the question that it had to do with a bigger problem being explained away. If it was a small amount of water, the seal at the partners might be leaking, or as you say, the mast is leaking internally. For some reason, I also had a wooden boat in mind.
     
  7. Omeron
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    Omeron Senior Member

    I find that freezing theory very interesting. I assume you are talking about water that had entered into the mast section and than froze. I would imagine any body of water with a free surface or any opening would be expanding in that direction while freezing and therefore would not cause a threat.
    Can you elaborate on that please?
     
  8. RHough
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    RHough Retro Dude

    Sure, In Canada, boats that get put up for the winter with the masts stepped (and the masts don't drain into the bilge properly when it rains) often end up with cracked mast butts. When the water freezes, a layer of ice forms on the free surface. This acts as a plug and it is no longer a free surface. The edge of the ice layer is stuck inside the mast and cannot move up to relieve the pressure below.

    Freezing damage also happens to sail luff grooves in furlers. If the furler is stored with the grooves up, and water freezes in the groove, it can crack the furler. Same for masts stored outside with sail tracks up. I would have thought that the open slot would prevent this, but I've seen it happen many times.
     
  9. Omeron
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    Omeron Senior Member

    Thanks RHough.
    That is very interesting.I always thoght a free surface was enough insurance.And the pressure generated would be great enough to break the thin plug.
    That must be something to do with very rapid freezing conditions and a metal surface, loosing heat through conduction before the mass of water.
    I shall remember this.
    God knows how many good bottles of white i destroyed, by forgetting in the freezer...
     
  10. RHough
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    RHough Retro Dude

    Yes ... freezing not so good for wine!

    If there is a limber hole in the mast so the water drains, I've never seen the mast damaged that way. The free surface of the bilge is big enough and the sides are tapered allowing the top layer of ice to move.

    Of course best bet is to keep the bilge dry during freezing conditions! :)
     
  11. mattplowman
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    mattplowman Junior Member

    thanks guys - i tasted the water and it was freshish - a bit brackish...was about an inch...issue is I had a look at a survey done last year and there were about 4-5 mentions on damp or wet areas - none of them serious but put together i am getting the feeling this is a "wet" boat...if you know what i mean
     

  12. PAR
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    PAR Yacht Designer/Builder

    As I mentioned, some water in a bilge without a sump well, is normal and can't be avoided. Never trust someone else's survey, have one done on your own, with special attention paid to leak sources.
     
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