Fixing a Leak on Wooden Mk1 – 12934

GP14 Sailing Forums Forum Fixing a Leak on Wooden Mk1 – 12934

This topic contains 11 replies, has 3 voices, and was last updated by  Dunc Llew 8 months, 1 week ago.

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  • #16609

    Dunc Llew
    Participant

    Have tried to fix a leak in a wooden GP by drilling holes around the Hog (from underside of boat) and filling with epoxy. After four attempts, it’s not worked! Any more suggestions? Number 12934 so probably not worth a professional repair so if I can’t fix, then it looks like it’s spares or repairs. Looked through previous postings but couldn’t find anything. Wondered if maybe the balers were causing it?

    Thanks

    • This topic was modified 11 months, 3 weeks ago by  Oliver Shaw.
  • #16614

    Oliver Shaw
    Moderator

    First,  please try to identify more precisely where the water is coming in.

    E.g. is it between plywood and hog,  or via a split in the plywood,  or between hog and centreboard case,  or through splits in the centreboard case,  or past the centreboard pivot bolt,  or via the self-bailers,  or via the transom flaps?

    One way to attempt to ascertain this is to get the boat fully dry,  remove the floorboards,  then launch her,  and immediately look to see where the water first starts to appear.    If that fails,  or if you need an additional check,  bring her ashore again,  put her on her launching trolley or otherwise support her,  get the outside of the hull dry,  then put a little water inside her  –  just two or three inches depth,  and see where it comes out underneath.

    Once we know where the leak is we may be able to advise,  but until we have that information there is not a lot anyone can do by correspondence.

    Hope this helps,

     

    Oliver

  • #16979

    Dunc Llew
    Participant

    Oliver

    Took floor boards off this weekend and launched onto water. Looks like the water is coming in from the two holes either side of the mast – not the holes with bungs in, the two smaller ones. Any ideas? Thanks.

  • #16980

    Oliver Shaw
    Moderator

    I am not entirely clear what holes you mean;   can you post photos,  please?

     

    Oliver

  • #16982

    steve13003
    Participant

    As Oliver says there should not be any holes either side of the mast, your boat should have a built in front tank for buoyancy and there will be one or two holes with bungs in the bulkhead in front of the mast.  Have you checked inside the buoyancy tank for water?  If you have leaks around the mast step area have you check for leaks with tension in the rigging? Presuming you have the original mast step with a square fitting at the bottom of your mast. Series 1 boats are prone to splitting the hog / keel joint under the mast step if high rigging loads are used – the preventive measure is to fit a load spreading mast step conversion which distributes the mast load into the centreboard case and forward towards frame 1, but first the leak needs to be fixed before fitting the new mast support (drawings from the GP Office).

    I have attached some pictures of an old GP No 13003 with the modified mast step, showing the finished work and the drain bung in the forward bulkhead – but you will need to fix the leak before fitting the new mast step. Also once complete you need to have the work checked by a class measurer and the details entered on to the boats certificate.

  • #16983

    steve13003
    Participant

    As Oliver says there should not be any holes either side of the mast, your boat should have a built in front tank for buoyancy and there will be one or two holes with bungs in the bulkhead in front of the mast.  Have you checked inside the buoyancy tank for water?  If you have leaks around the mast step area have you check for leaks with tension in the rigging? Presuming you have the original mast step with a square fitting at the bottom of your mast. Series 1 boats are prone to splitting the hog / keel joint under the mast step if high rigging loads are used – the preventive measure is to fit a load spreading mast step conversion which distributes the mast load into the centreboard case and forward towards frame 1, but first the leak needs to be fixed before fitting the new mast support (drawings from the GP Office).

     

    Steve Corbet

    • This reply was modified 9 months, 1 week ago by  Oliver Shaw. Reason: Removing formatting commands
  • #17135

    Dunc Llew
    Participant

    Happy New Year to you both. Have taken a couple of shots to show the extra holes and the set up. You’ll see there is the big hole where the bung goes and then a smaller hole which is where the leak is coming from. It’s the same on the other side of the mast, ie four holes altogether. It leaks equally out of each small hole; it’s only a trickle, but obviously builds up over an hour’s race. Thanks.

     

    Duncan

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  • #17140

    steve13003
    Participant

    Dunc

    The pictures clear up one point your boat already has the mast step modification. So that is one point in its favour.

    The holes seem to be the limber holes in the frames which allow water to drain through the boat, there should also be a hole under the mast step support to allow water to move from side to side.

    Looking at the pictures your boat has built in spinnaker storage boxes – is it a Duffin hull? these were an optional extra he offered which further help to stiffen boats around the mast and shroud area.

    Your water problem is a mystery without actually seeing the boat, have you checked inside the front buoyancy tank after sailing? could water which slops into the boat while sailing get into the tank? does the bung rally seal the tank.  You could do a simple pressure test on the front tank, insert a length of garden hose into the bung hole, seal it with BluTack, plasticine or similar, blow gently into the tank and listen for and escaping air or brush soapy water around your holes and look for bubbles.

    It is of course still possible that the hog to keel joint has sprung even though the mast step conversion has been carried out, only way to check that is to rig the genoa, apply your normal rig tension (400lbs is normal for a good strong boat) fill the area around the mast step with water and look for leaks on the outside of the boat.  If you do have leaks in this area they can be difficult to fix, first you need to strip off the paint on the outside and the varnish on the inside and the get the wood as dry as is possible.  Then you will need to open up the cracks by applying the rigging load and the inject the cracks with SP106 epoxy resin.  I have also found a single shot marine crack filler Captain Tollys Crack Cure Sealant – not yet tried it in real anger but it is supposed to fill very narrow cracks in all materials.

    Good Luck Steve

  • #17141

    Oliver Shaw
    Moderator

    I concur with the diagnosis.   Immensely difficult to identify the source of the water problem without seeing the boat,  but checking the buoyancy tank is an obvious first step;   if you are still sailing at this time of year then having a look inside the tank immediately after sailing will tell you whether water is getting in there.

    I am less confident about dealing with cracks,  if found.    Injecting epoxy or other materials may stop the leak initially,  but I would expect that whether this works on a long term basis would depend on whether the crack is still subject to movement under load.   If such a repair amounts to no more than a (dubious) butt joint in cracked plywood it will have little structural strength,  and may well not prevent the crack moving under load,  leading to the repair soon failing.    Much may depend on the location of the crack,  and the strength and rigidity of the surrounding structure.

    If you are confident that the crack occurred before the mast step conversion was done,  and that the work already done will absolutely prevent the crack now moving,  then the structural rigidity is already assured and filling the crack may be all that is needed.    If not,  some serious woodwork may be needed.

    If it is a crack in the plywood (only),  and there is an accessible area all round the crack to make a structural repair,  a backing piece on the inside and/or a scarphed or layered insert of fresh ply would be stronger (but a lot more work).

    Good luck.

     

    Oliver

  • #17142

    Dunc Llew
    Participant

    Thanks both for your replies, you’ve been very helpful. It looks like it’s a project for someone with more practical skills than I possess so will look to put up for sale in the Spring. I learnt to sail in this boat – even capsized with the previous owner on my test sail – so it will be sad to see it go.

    Duncan

  • #17171

    Oliver Shaw
    Moderator

    There is an alternative to selling her.

    In the course of looking for something else I have just unearthed a set of photos of a boat which is presumably leaking,  because the owner has named her Leaky Bottom.

    So perhaps continue to sail her,  and rename her Leaky Bottom II ?

    Seriously,  a partial solution,  if you can identify where the water is entering,  is to inject a polysulphide mastic from the outside,  or a specialised marine sealant such as CT1 (which is described as a hybrid polymer).   This will remain flexible,  so the repair won’t be harmed by subsequent slight movement.    Obviously I can’t guarantee success,  but it is a low cost approach that seems perhaps worth a try.

    https://www.marinescene.co.uk/product/4920/c.t.1-underwater-marine-sealant

    http://www.discount-trade-supplies.com/shop/product/2057-CT1_Sealant_Adhesive_ctec/

    https://www.sealantsonline.co.uk/ProductGrp/Ct1-unique-all-in-one-sealant-adhesive

    for three suppliers (there are probably others as well).

     

    Oliver

  • #17183

    Dunc Llew
    Participant

    Oliver

    That looks a brilliant product. Will have another look at the hull and see what I can find. I have put it up for sale in the meantime; it was a shared boat we sailed on the Trent which I brought down to Sussex when we moved so don’t have a regular crew any more. Was keeping it for sentimental reasons really but haven’t used it much as I thought so it’s time for a change. Thanks again for all your help.

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