Latest News: Forums Technical A very basic question on mainsheets!

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  • #3801
    Anonymous
    Inactive

    I have set up a 3:1 aft mainsheet which suits my purposes. However I find the rope seems to take a ” set” and with a swivel the 3 lines between the blocks naturally twist around, increasing the friction, despite no lines crosing over when I launched. Any wisdom appreciated.
    Cheers Dave

    #7333
    Anonymous
    Inactive

    Perhaps I should add a couple of facts. I noticed this problem yesterday after circumnavigating Hayling Island from Itchenor (fantastic trip) and so had been sailing for 6 hours with plenty of tacking. Secondly this was my first time with 3:1 (previously it was 4:1) but I wanted to reduce the friction. Finally both blocks have swivels, the single block has the end of the mainsheet spliced onto a fixed eye on the block, the double block swivels mounted to the old and battered traveller track. I’ve just inspected the mainsheet and it had developed quite a twist which is probably just the end result of a long sail and answers my question as to the cause, but still interested in any comments. Should it be a routine job to untwist (rotate) the mainsheet until it is supple and lying nicely through the blocks?

    #7337
    Bob Harland
    Participant

    Swiebertje recommends separating the fixed end of the sheet – read the topic on the link below. Although that’s for a centre sheeted main I guess the same is true of aft. Not sure how much you have separated your fixed eye.
    http://wayfarer.org.uk/forum/viewtopic.php?t=521

    So far we don’t seem to have this problem on W7658, I wonder if it is a feature of a mainsheet after a few years use?

    Incidentally, you want to resist the tendency for the rope to twist rather than allow it.
    I cannot quite picture your arrangement, but I imagine the mainsheet tail will stop swiveling at the boat end. So take the swivels out of the boom end.

    bob

    #7339
    Dave Barker
    Keymaster

    Dave – I think part of the problem is having a swivel on both blocks. They tend to chase each other around.

    #7340
    Anonymous
    Inactive

    Thanks for the replies Bob and Dave. My fixed eye is to the becket (?) on the single block on the boom so perhaps I could separate it as Swiebertje suggests. I can easily remove the swivel on the block on the traveller which will therefore be my first action. Can’t change the swivel on the boom block without changing the block so that will be a question of how much the problem bothers me (a six hour sail is a rarity to say the least).

    I don’t think the mainsheet is particularly old but that could certainly be the cause of the same problem as this happens on my Lugger too (although that sheeting system is bizarre after a Wayfarer).

    Bob, I’m not sure what you mean by
    “Incidentally, you want to resist the tendency for the rope to twist rather than allow it. ” but I presume you are saying I should stop the cause of the problem rather than regularly untwsting it, as it won’t do the sheet any good.
    Anyhow thanks for the replies. Need to go for another sail to test it all out.
    cheers Dave

    #7343
    Anonymous
    Inactive

    “Laid” rope will always have a tendency to try and twist when tension is applied and released. By allowing all your multiple purchase blocks to swivel you are actually allowing the rope to unlay itself under several hours of repeatedly applied tension, which is a bad thing.

    The transom end is ok with a swivel, as the tail being led to your hand prevents it from turning a full circle, so the swivel performs its intended purpose of allowing the sheave to align in the direction you are pulling.

    Wheat you need to prevent is the block at the boom end from swivelling. When you think about it there is never a valid need for it to swivel as it always operates in the same plane, relative to the other block. Shackle it directly to the boom eye so that it can swing but can’t swivel and your problem should disappear.

    I don’t think in this instance you should lead the bitter end to the boom, as it would then have to cross (and potentially bind with) one of the other running parts. Leave it on the becket, just prevent the block from swivelling.

    #7346
    Anonymous
    Inactive

    Thanks John, the advice is clear, the boom block swivel must go!

    #7351
    Dave8181
    Member

    The action of pulling in the mainsheet (or kicker or whatever) can build up a twist in the rope, as your hand can turn slightly, every time you pull the rope.

    To avoid this you can simply twist the free end of the rope a few times the opposite way, then sheet in & out to apply this untwisting to the rope. Additionally if you fit the mainsheet with only a 2x at the back of the boom and sheeting to the thwart (ie standard thwart sheeted mainsheet with a rear bridle), this will be less of an issue. With this set up, with the sheet going almost block to block on a beat, and 2x purchase, there is less potential for a twist in the purchase.

    Dave8181

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