Home Forums Mods and Improvements Dyneema leader for mainsail halyard

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  • #2168
    Paul White

    The mainsheet halyard has a 25cm wire leader which has a loop on both ends each held by a brass swage. The swage on the pulled end is designed to catch in the V-cleat on the mast so that the strain of the sail is taken at the top of the mast and not transferred directly to the cleat at the bottom. This has a number of issues:

    1. The swage can come undone where it is clamped onto the wire causing the sail to fall down – especially in strong winds or if you pull the Cunningham on hard.
    2. The swage can catch on the side of the V-cleat so that you think it is fixed in position but it then comes loose as soon as you start sailing
    3. The wire leader introduces weight at the top of the mast where you want it least since it adds to the pendulum effect

    The solution is to replace the wire leader with a Dyneema leader which is attached to the mainsail shackle at one end and then spliced to a regular rope which leads down to the cleat at the foot of the mast.

    A knot in the Dyneema is used to catch in the V-cleat.


    1. Dyneema is lighter and stronger than wire and there’s no swage to come undone (it happens)
    2. The Dyneema leader can easily be replaced if it becomes worn.
    3. The rest of the halyard can be made from any rope that can be spliced to Dyneema but Dyneema core is recommended.
    4. You can DIY and replace the leader easily


    Dyneema Leader
    Peter Martin’s spliced system above uses a 1.75mm Dyneema leader spliced to a 4mm halyard line with a Dyneema core.

    You could just use a single Dyneema rope for the halyard and splice a loop on the end of it –  but if it gets worn out you’d have to cut off the end of the rope and possibly replace the entire length if it got too short.

    By having a leader you can have a sacrificial length of rope and then use cheap and thin line (reducing wind resistance) for the section to the mast cleat since that’s not under strain. My leader is made with 1m of 3mm Dyneema with a loop spliced into either end. One end of the leader goes through the loop on the end of the halyard and back on itself. The other end goes through the sheeve at the top of the mast and has the shackle for the mainsheet head attachment. Tie the knot to catch in the V cleat 25cm from the shackle on the end.

    TIP: If the knot doesn’t catch in the V-cleat make it larger by tying another loop over the top but don’t make it so big that it won’t pull out of the V when you pull down on the halyard to drop the sail.

    TIP: If you find it difficult to splice 3mm Dyneema with a Fid, try using a piece of coathanger wire with the ends rounded off – push it through the Dyneema core and tape the end of the Dyneema in line with the end of the wire, then pull it the wire back through the Dyneema to thread the Dyneema through.

    Instructions for making the splices

    For the halyard (Double braided rope version here)

    For one end of the leader.

    For the other end of the leader

    • This topic was modified 2 years, 9 months ago by Paul White.
    • This topic was modified 2 years, 8 months ago by Paul White.
    • This topic was modified 1 year, 3 months ago by Paul White.
    • This topic was modified 1 year, 3 months ago by Paul White.
    • This topic was modified 1 year, 3 months ago by Paul White.
    • This topic was modified 1 year, 3 months ago by Paul White.
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