Maxi 95 Conversion

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  • 22 Mar 2017 19:23
    Reply # 4683610 on 4592562

    Brilliant!  I love the out of the box thinking.  I will have a poke around under the sole next week, but that sounds like a very sensible and attainable solution.  Many thanks, David.

    Mark

  • 21 Mar 2017 19:26
    Reply # 4680867 on 4592562

    My feeling is that I would make a hole big enough to get a hand down inside the cavity, and to get a torch and mirror down there. I would do whatever was needed to seal the edges of the cavity, then pour in a slurry of resin filled with something that will absorb exothermic heat, eg, dry sand. Then go ahead with building up the layers on top of a very solid base that is well bonded to the hull.

  • 21 Mar 2017 19:15
    Reply # 4680821 on 4592562

    I have uploaded a photo here of the place where the foot of the mast needs to go - between the main bulkhead forward and my size tens at the bottom of the picture.

    The maximum depth beneath the cabin sole is about five cm, by my best guess, reducing to less than half that forward under my wellies.  Having looked again, and with my usual decisiveness, I am now leaning back towards plan a - three or four layers of ply built up on top of the existing glass fibre cabin sole, completely filling the available space, with the mast step on top of that. The other option would be to remove the glass fibre sole and build up a wooden one from the hull, but it seems to me that option will add complication without giving much in the way of extra strength and some further reinforcement of the bond between the inner and outer mouldings under the berths may help me to sleep better at nights.

    As always, though, I am keen to be corrected if my thinking is awry.

    Many thanks,

    Mark

  • 20 Mar 2017 12:42
    Reply # 4677697 on 4592562

    Thank you to all for your responses. David - I guess yours is the big question.  The visible part looks strong enough - neatly bonded with a radius of about two cm. But what, if anything, is holding it together on the less visible time is unknown. I suppose, more specifically, the question is whether I trust the bond enough not to stress on a dark and windy night at sea! I am travelling today, but will have a closer look later on in the week and maybe take some pictures to share. I have to say, though, that I am now leaning more towards removing at least some of the moulding that makes up the cabin sole.

    Mark

  • 20 Mar 2017 00:30
    Reply # 4676948 on 4592562

    Hi Mark,

    my question is how well is the liner fastened to the hull? As the lateral forces from the mast will be transferred to the liner in your suggested solution, and not to the hull, then this could be the critical junction. It may be advisable to investigate this further and if doubtful then cut through the liner and fasten directly to the keel, possibly incorporating the liner into the mast step as it passes through. What is the distance between the liner and the keel? I am assuming both are fiberglass. One way of doing it may be to build up with composite plywood and fiberglass solid from the hull to the liner and then build the mast step on top. Of course it all depends on access to the space.

    All the best with the project, David.

  • 19 Mar 2017 22:33
    Reply # 4676836 on 4592562
    Anonymous member (Administrator)

    Mark,
    I let you have a half-finished draft with photos showing the building of the mast step for Ingeborg. I just sent it over to you.

    Arne

  • 19 Mar 2017 21:05
    Reply # 4676758 on 4676650
    Mark Case wrote:However, having reread that section in PJR, they talk about consideration of "pile driving" force.  The moulding is strong, as in it does not visibly flex when I jump up and down on it, but the mast and rig will weigh a fair bit more than my paltry 70 kilos. Would any off our members with more experience be willing to quantify that 'pile driving'? I certainly do not want to be worrying about the mast going through the floor as I go to windward.  Should I be cutting out the internal flooring and taking the mast step support right down to the keel?

    Many thanks,

    Mark

    Most of us secure the masts so that they can't jump up and down.  (David Lewis failed to do this, with disastrous consequences.)  On Fantail, I used two U-bolts and a bottle screw, which I thought was rather an elegant solution.  Assuming the mast is held down and that it is wedged firmly in its partners, there should be no 'pile driving' effect in the way you mean.  In sailing parlance, it's also used to refer to a boat going to windward and getting nowhere, with the boat pitching violently; and I think that's how it's meant in PJR.  A boat being pinched to windward and with no camber in its sail, can be prone to this behaviour in certain types of chop or swell. 
  • 19 Mar 2017 19:43
    Reply # 4676650 on 4592562

    The sections of the mast partners are now all made, ready for epoxying when the weather is warmer (although I do have permission to use the kitchen table if that warming does not happen soon).  There is a picture here .  Cutting out the angled hole for the mast was fun (!) and the finished product is far from perfect, but I think I will borrow an idea from David Tyler and use a bucket coated in release agent put down the hole when glassing to smooth out the wobbles.

    Next step is the mast foot.  At the moment that spot is occupied by an internal moulding that makes up the fore cabin floor and bunk bases, about seven-eight mm think and between 30-40 cm across from where it bonds to the hull sides at the site of the proposed mast step. My intention was to build up the floor with another 24 or 36 mm of ply then make an Arne style cup of 6-8 layers of 12mm ply, going right across from port to starboard and butting up against the bunk sides, which are also part of the internal moulding.  However, having reread that section in PJR, they talk about consideration of "pile driving" force.  The moulding is strong, as in it does not visibly flex when I jump up and down on it, but the mast and rig will weigh a fair bit more than my paltry 70 kilos. Would any off our members with more experience be willing to quantify that 'pile driving'? I certainly do not want to be worrying about the mast going through the floor as I go to windward.  Should I be cutting out the internal flooring and taking the mast step support right down to the keel?

    Many thanks,

    Mark

  • 27 Feb 2017 21:35
    Reply # 4637964 on 4636853
    David Tyler wrote:

    The conduit itself needs securing, or it will bang about. This is something that I omitted to do before stepping the mast. Now I will have to go halfway up the mast, drill a 5mm hole, spray in a mist of water and then insert the straw of an aerosol of polyurethane foam (water is what cures a one-part polyurethane). Polyurethane is long lasting and will adhere to almost anything. A good big plug of polyurethane foam should fix that pesky conduit.

    Thank you for that David.

    The cables and/or conduits inside the aluminium alloy masts on Lexia make a frightful noise.  I have been wondering for some time on how to tackle that.  

    The prospect of having to lift two large masts to rework the innards does not bear thinking about.  

    I had therefore been pondering whether one could drill a hole in the cap on the mast and pour down small balls, presumably something like polystyrene pellets to fill up the mast.  (If the cap was big enough and one made a big enough hole then maybe table tennis balls !)  The repair the hole in the top of the cap.  I would guess that weight and moisture would not be issues.  

    However, maybe you have provided me with a more viable alternative.  

    I suspect that I would have to inject the foam in more than one place.  However, perhaps I should start with one injection in each mast and see if it stops the noise or not.  If it only reduced it the noise one might then be able to presume that one was on the right lines.  

    Would you have any reservations on a me putting a number of 5mm holes?  It might be sensible to stagger them round the circumference rather than in a straight line.  

    Does a 5mm hole cause any significant weakness?  I would guess not but would be open to advice from anyone.  I presume that one should try not to make  holes near the deck partners.  I was at one time advised that if after drilling a small hole one filled it with a monel rivet then it was as strong or stronger than before it was drilled.   

    All suggestions welcome.

    (Maybe this topic should be included in some other thread title as being of more general interest.)  

  • 27 Feb 2017 19:45
    Reply # 4637797 on 4637085
    Tim Stewart wrote:

    This central heating pipe insulation is still available, although the name may vary.

    http://www.jtmplumbing.co.uk/productimages/17985/0/0


    Regards Tim

    I've used this in the past (for fendering), but it's a lot more expensive than pool noodles.  On the other hand, it does come with self-adhesive edges, which can be a bonus.  It will be quieter in the mast than the pool noodle, but neither will clang.

    (Covered in cloth, it makes beautiful fendering which works wonderfully well, as long as the dinghy doesn't spend any time alongside rough, concrete walls.  But it's too soft to take any real abuse.  The product for that is alkathene, which protects the dinghy from just about anything, but is a bit hard on your newly-painted topsides, which it will tend to scuff, once it becomes chewed up.  For those whose dinghies only go between dedicated small boat float and mother ship, I can recommend the central heating pipe insulation.)


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