Is boom vang needed on cat with long rear traveler track?

Discussion in 'Multihulls' started by massandspace, Jan 15, 2018.

  1. massandspace
    Joined: Sep 2017
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    Location: Salt Chuck

    massandspace Junior Member


    I am building a custom mini-cat...27' by 15'.

    It would be very hard to install any type of vang system for the boom on this boat as there is a full pilothouse structure in the way. I was planning on a dual-sheet type of system instead, but recently have been told to just use a track and single problems.

    My question is will that type of system work? The beam of the boat is about 15', and the track can be a maximum length of 9' I need a vang? If so, would the dual mainsheets be a better choice to prevent the boom from rising?

    Thanks for helping....
  2. Blueknarr
    Joined: Aug 2017
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    Location: Colorado

    Blueknarr Junior Member


    I often find it handy to control boom rise separately from boom angle. I have even been known to ease vang and engage topping lift to induce twist.

    The tri I sailed had a series of pad eyes that a temporary vang could be rigged to. Added an extra step to tacks n jibes, but provided greater sail control.
  3. Tom.151
    Joined: Jul 2009
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    Location: New England, USA

    Tom.151 Senior Member

    A circular track is the way to go if you want to eliminate the vang most effectively - probably don't need a full 180 degrees of coverage (maybe someone here has useful experience for you on that). Make a sketch of the boat - so you can lay out a perfectly semi-circular track where it interferes the least with the arrangement and other hardware.. Even if you need to attach the main-sheet toward the middle of the boom (instead of at the very end) just plan on beefing up the boom strength.

    Shown is a circular track - but for the vang on a Star class - which might serve you on the pilothouse roof... which is another way to go

    Attached Files:

    fallguy likes this.
  4. guzzis3
    Joined: Nov 2009
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    guzzis3 Senior Member

    Or put a track on the boom so the main sheet is always vertical, assuming your boom is long enough to reach the traveler at the wider sheeting angles. Much cheaper than a curved traveler track and easier to install.

    I'm no racer but as I ease the main for a broad reach I don't bother with tweaking sail shape that closely so maybe you only need a traveler track about 2 meters ?

    At what point is the end of your boom no longer directly above your traveler ?
  5. Munter
    Joined: Jul 2007
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    Location: Australia

    Munter Amateur

    The answer is... it depends.

    It depends on several things.
    1. Is your cat fast or slow. A full pilothouse suggests leisurely pace and therefore broader wind angles and eased sheets. A vang can be helpful here but a longish traveller will substantially compensate. If however, you want to run square with a main without a vang you will have to learn to live with a lot of twist. Fast cats don't need a vang because they don't need to deal with sheets eased much beyond the traveller.
    2. It depends on how much efficiency you are willing to trade off for convenience. A vang might improve sail control but if it only costs you a couple of percent and significantly improves layout options then maybe it is worth it.

    Sailboat design is all about trade-offs.
  6. redreuben
    Joined: Jan 2009
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    redreuben redreuben

    Use a wishbone boom.
  7. philSweet
    Joined: May 2008
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    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    A reasonable option is to have a decent, but not maximal main traveler, and use a handy-billy to an outboard hard point for occasional deep downwind sailing. This gives you double sheeting as an option whenever you want it. It also permits using a straight traveler track. It's a nice option to have when short handed in a good breeze because you can set it up to lower the trimming effort on the main. This can make for a considerably less messy traveler system most of the time by keeping the traveler control lines from taking over the boat. Can you post a sketch of the aft half of the boat showing rudders and tillers and their control line routings? How long is the boom and how tall is the mast?

  8. captaingregger
    Joined: Mar 2018
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    Location: Los Angeles

    captaingregger New Member

    I don't use a vang on my trimaran. She's heavy, yet fast. The issues facing multihulls are that they don't spill the wind that a mono does in the heel. Therefore the loads are exponential as wind velocity increases. Accordingly, I find myself spending less time concerned with mainsail trimming an performance when the wind is abolve 10-12 kts. At that point I'm looking at what I need to do to slow the boat down (due to increased load on all the gear), unless on a beam reach. In that case I'll usually push it to 14-15 kts (fast for a fully outfitted curising tri like mine). But when I reach those speeds it's usually only a matter of hours before some shackle or line blows out and I'm back down to 7-9 kts.

    So I like a little twist in the main to help spill the air, sort of keep her under control if I can.
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