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  • #4656
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    Hi, my elderly and much loved Mk2 has developed some damage in the GRP down at the foot of the tabernacle at the level that the floor panels sit and extending a little above and below. On investigation it turns out there is some wood, a sort of fillet inside the forward buoyancy tank fixed with 4 bolts, the heads of which are in the floor void, has become saturated with water, swollen and rotted a bit, and it is the expansion of the wood that has cracked the GRP.

    I have ground out the damage and replaced it with laminated glass cloth and epoxy, spreading the repair well beyond the site of the damage, digging out some black rotted wood in the process. I am content that the GRP is sound but that does not solve the problem. I will find out where the water is getting in and seal it, and I will ventilate the tank to try to dry it out.

    I emailed Ian Porter who tells me that he has repaired similar before, accessing the task through the 5 inch hatch (tricky) but I will wait until the autumn so as to not miss out on too much good sailing weather.

    Has anyone else experience of such a problem? How was it solved? Has anyone had a repair done, if so any idea of the cost?

    Mike
    Kez 4137

    #11857
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    Mike
    I have removed and replaced pretty much all the wood in my plastic mark 2.
    To gain access to the wood in the front tank I added an extra buoyancy tank hatch [in accordance with the measurement rules] and used an inspection lamp and a car wing mirror to see what I was doing. With two access holes you can look in one while working via the other.
    As you say, the wood was included as part of the original fabrication to provide strength to the fibreglass moulding. The load bearing properties of the wood had been lost over the years due to the effect of water damage. I removed and replaced a piece from under the moulding which transferred the load across the boat as well as a stack of delaminated ply from under the mast foot itself, intended to spread the point load from the mast foot.
    From memory, the long piece was some three feet or so long by an inch or so wide by four inches deep at the centre, narrowing to meet the shape of the buoyancy tank at the ends. There was no strength left in either piece. Upon removal, the longer piece of wood was initially quite flexible, providing absolutely no support and once it had dried out, it looked porous and well past its best. The plywood pad looked like it was originally made up from several bits of ply, the whole thing ending up to be about three inches thick. I think the load was transferred through the sides of the pad, as it was held in place by a bit of mat that would have only been of use as a restraining strap during the build as it was flimsy in comparison.
    The water ingress was probably via the fixings holding the mast foot track; easy for the moisture to get in but not out again. I had owned the boat a couple of years before I realised, while carrying out the Mike McNamara set-up procedure, that these wooden supports were not working as designed. I would have described the buoyancy tank as a bit damp, but not particularly wet. Note that it passed the pressure test like this and was quite usable although I spent a lot of time wondering about the cracks to the mouldings around the tabernacle.
    In your case, the fibreglass may have been damaged by the expansion of the wood; however I doubt it, although I am not sure, I would think the fibreglass would be able to withstand the forces involved as the wood swelled as it soaked up moisture. In my boat, the damage to the glass was caused by the inability of the structure to withstand the rig load, once the structural properties of the wood reinforcement had dwindled away.
    I would also be thinking about whether just drying the wood will achieve what you require.
    regards
    Jamie

    #11858
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    Excellent advice, thanks Jamie, it’s great to know there is someone out out there who has the experience of removing the wood. Was it glassed in, do you remember?

    I have thought about not only another circular, rules compliant access hatch but cutting out a big square hole on either side of the tabernacle for access then laminating some new white GRP lay-up on a piece of glass and after repairs stitch the new panels back into place, but your advice that it can be done by keyhole surgery is refreshing and not quite so drastic.

    Did you replace it with a similar piece of wood or something more durable? I can see that there is a very thin piece of ply glassed edgewise under the deck, on the centreline extending to the bows supposed to stiffen it I guess but doing a particularly fine job.

    I will wait until a bit later in the year to either have a go or give it to Ian Porter to fix. I suspect it will be like pulling a piece of string, the more I probe, the more I will find.

    It is such a pity they used wood in these boats, my old Enterprise had much the same problem with even less opportunity to get inside tanks to fix problems.

    Mike

    #11869
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    Dropped Kez off at Ian Porter’s establishment at Emsworth on Saturday and I have asked him to remove the old rotten wood and replace the support to the mast.

    Feeling around inside the forward buoyancy chamber I could not find anything that was supporting the tabernacle base, it had not rotted away, it just wasn’t there, so maybe that’s why the GRP has cracked. I will talk to Ian on Monday and ask him to make sure that the load is being carried by the new ply/ packing he will be fitting for me.

    Hopefully a complete solution.

    Mike

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