Latest News: Forums Technical Setting up a wooden mast

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  • #3756
    TimTownsend
    Participant

    I’m nearing the end of my restoration of W978 and I need to start thinking of how I set up the wooden mast.

    Do I have to keep the mast pin in or is there a way of securing the foot as with an alloy mast?

    Also has anyone experience of applying foresail tension with a muscle box on a wooden mast? I ask this because the halyards come out of a wooden mast higher up compared to an alloy spar.

    Look forward to any advice.

    For those who are aware of the restoration saga of 978………….We will be sailing by……………….

    T

    #7085
    Anonymous
    Inactive

    @tim wrote:

    I’m nearing the end of my restoration of W978 and I need to start thinking of how I set up the wooden mast.

    Do I have to keep the mast pin in or is there a way of securing the foot as with an alloy mast?

    The class rules say you must have a mast pin. Clearly it would be better not to have one from a rig tuning perspective, so the best compromise is to use the minimum diameter pin (think it is 6mm) so that it is a loose rattling fit in the hole, then have a shoe that the mast heel slides into from behind to postitively locate it at front and both sides, and to take the weight of the mast (and the vertical rig load). Then you want a snug fitting pair of side cheeks at deck level so that the mast is properly supported there as well, and ideally a set of chocks (or other arrangement) to control mast bend at deck level. The critical thing being that when the rig tension is applied the pivot pin is still a rattling loose fit and not subjected to any pressure.

    Not sure about the muscle box – how far up the mast does the halyard exit? On my alloy mast it runs down the luff groove and pops out just under the gooseneck so I have a highfield lever on the back of the mast at about deck level. I guess your muscle box could go there, or if concerned about how to securely fasten it to the mast then why not mount it horizontally on the side of the c/b case with a short strop leading via a (securely bolted) turning block and hooking into the halyard.

    For those who are aware of the restoration saga of 978………….We will be sailing by……………….

    So soon? 😉

    #7087
    Anonymous
    Inactive

    Hi John,
    Thanks for that very logical advice. It will be interesting to see how the spreaders work as they are the wibbly wobbly kind! i.e they flop and turn in all directions when not under tension.

    I have aquired a pair of aerodynamic ones, which may fit and provide the correct distance tip to tip.

    Just been out cleaning the decks up, hope to epoxy this weekend.

    Here are a few pictures taken over the last 7 years.

    T

    T

    #7089
    Swiebertje
    Participant

    @tim wrote:

    It will be interesting to see how the spreaders work as they are the wibbly wobbly kind! i.e they flop and turn in all directions when not under tension.

    If that is true you may just as well sail without those spreaders. Only when they are fixed in position they are usefull. At the ends the shroud should make a small angle and the top and bottom angles between spreader and shroud must be equal. The same goes for forward/backward motion. The spreaders are supposed to put a force on the mast at a certain angle and help the mast bend as we want it and it should be the same each time we step our mast. If the spreaders are not fixed and slide down the shrouds they do nothing. In the odd case that they do bring some force to the mast it is an uncontrolled force and chances are high the result is not what you want. Worst of all the result is not repeatable.

    The shrouds should not move up and down at all and divide the shroud angle evenly. Most of us have control over the spreader width and the forward/backward angle but once these parameters have been set we usually lock the spreaders in place by a split pin or other means. That way the mast trim is accurately controlled and the same each and every time we step our mast.

    #7090
    Anonymous
    Inactive

    Yes and no….!

    My boat also has what you might call “floppy” spreaders, but I don’t regard them as being useless.

    Firstly, whilst they are free to rotate forwards and backwards the fact that they are held by a vertical pivot pin means they can’t move vertically.

    Secondly, the fact that they are longer than the distance the shrouds would otherwise be from the mast means that when rig tension is applied they MUST deflect the shrouds outwards.

    The net effect is that they support the mast from sagging away to leeward by transferring the sideways load from the mast to the shrouds which are in tension.

    I agree that a freely swinging spreader doesn’t control mast bend, but given that my trusty old mast is about as bendy as a telegraph pole I’m not really bothered that I can’t wind on the spreader adjusters to reduce mast bend and power up the sail.

    In an ideal world you’d have a nice floppy mast to allow the mainsail to depower in strong winds, and you’d wind on mast ram and spreader deflection to hold it straight in medium winds; but if your stuck with a mast that is too stiff to start with then the lack of fore and aft support from the spreaders is (in my opinion anyway) a fairly minor issue.

    #7092
    Anonymous
    Inactive

    Going back to the description of my floppy spreaders! They are the tubular type and are hopefully going to be stable when the mast is raised and shroud tension is applied.

    The wooden mast is definately stiffer than the alloy and therefore maybe it would be overkill to try and set it up with an adjustable set of spreaders.

    Sounds like there will be a little bit of fettling when it comes to the rig.

    Hope the rain doesn’t appear as I really want to get the decks epoxied this weekend!

    #7094
    Swiebertje
    Participant

    @John1642 wrote:

    My boat also has what you might call “floppy” spreaders, but I don’t regard them as being useless.

    Firstly, whilst they are free to rotate forwards and backwards the fact that they are held by a vertical pivot pin means they can’t move vertically.

    Secondly, the fact that they are longer than the distance the shrouds would otherwise be from the mast means that when rig tension is applied they MUST deflect the shrouds outwards.

    If you prevent them from moving down you are right. I have seen boats with spreaders drooping down to the point where the shrouds were going in a straight line up to the hounds. In that case they are completely useless. Other than that you may be amazed of the effect preventing them from moving forward or backward, even with a wooden mast. You don’t need fancy adjustable spreaders to do that, just set them up correctly, then drill a hole and put a pin in it. (A bolt and nut works too). But you are right in that the most important thing is to stiffen up the mast sideways. And that is done by preventing vertical movement of the spreaders and by making sure they are long enough.

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