Rigging procedure

Discussion in 'Sailboats' started by SailorStan, Aug 12, 2015.

  1. SailorStan
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    SailorStan Junior Member

    I have an adjustable back stay, my spreader is straight and I have two short side stays (a forward and rear side stay). The adjustable back stay allows me to bent the top half of the mast. How do I set the tension on the front stay?
    When I tighten the back stay the rear side stay tension is decreased and the tension on the forward side stay increases. Should the three side stays be set with the same tension when the back stay is slack?
    Any help on the order for setting the rigging would be appreciated.
     
  2. jehardiman
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    jehardiman Senior Member

    You don't...

    Make sure the mast us straight upright in the boat, then adjust the backstay as needed to prevent forestay sag when sailing. No sails up, both forestay and backstay should be loose to the hand
     
  3. SailorStan
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    SailorStan Junior Member

    Thanks Jehardiman,
    What about the three side stays on each side. Should they all be the same tension?
     
  4. philSweet
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    philSweet Senior Member

    The backstay tension determines the head stay tension. The jib sail is cut for a particular headstay tension.

    The lowers must have the proper total tension, as well as being biased to dial in the bend, this has only a small affect on headstay tension and can usually be ignored unless you are a serious racer who retunes for every race.
     
  5. PAR
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    PAR Yacht Designer/Builder

    The wires on the sides of the mast are called shrouds, not stays. Stays are positioned fore and aft (if necessary). Rather than focus on tensions from one wire to the next you should concentrate on balance. For example a cap shroud should have the same tension from side to side, the same will be true of the lowers or any other shroud. Additionally, no they're generally not all the same tension, though are balanced side to side, to keep the mast vertically oriented.
     
  6. jehardiman
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    jehardiman Senior Member

    Phil is correct about how serious you want get. The shrouds should have just enough tension to keep the mast in column under the sail load. For most sailboats this means that the leeward shrouds will almost be loose. For serious bendy racing masts with non-stretchy sailcloth, you will need significantly more shroud tension as well as runners to control draft location. Too much shroud tension will cause high compression loads and damage the hull, which is one reason why racing boat tend to be short lived.
     
  7. SailorStan
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    SailorStan Junior Member

    How do you find out what the head stay tension should be for an existing sail that you have? I am not into racing, my boat came with three head sails. I just bought a boat and I am just trying to figure this all out.
    The tension gauge gives a setting for the diameter of wire that you have. From what I am reading here that is too high and would put too much load on the boat unless you are racing.
     
  8. gonzo
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    gonzo Senior Member

    Is your mast stepped on deck or on the keel?
     
  9. The Q
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    The Q Senior Member

    I'm sorry but all the advice above is wrong....
    Why?
    Because you haven't described your rig well enough
    We need to know if the rig is deck stepped or Hog stepped and clamped at the deck or not.
    We need to know if your rig is fractional or not.

    For instance, Not all masts are set at vertical, if you did that to the class I sail it would sail like a dog, the mast is set with a lean back equivalent to about at foot at the top.
    It is also fractional rig, hauling on handfuls of backstay will not make any difference to the forestay tension because that is set by the shrouds, the underdeck forestay tension and the jib halyard tension. The backstay just bends back the top 1/4 of the mast. (normally in high wind sailing)
     
  10. SailorStan
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    SailorStan Junior Member

    The mast is stepped on the deck in a pocket. I intend to make a hinge bracket for it so that I can raise it by myself. It is not fractional rigged, the fore stay goes to the top of the mast. When the turnbuckle on the fore stay is tightened all the way the mast is still raked back about a foot. With the forward shrouds tightened all the way the mast is raked back 6" and the fore stay is completely slack.
     
  11. The Q
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    The Q Senior Member

    Now if your boat is a well known class there is a "magic distance". That is when a tape measure is pulled up to the top of the mast and then the distance to the turn of the transom is measured, it should be approximately this "Magic distance", which will be known among class owners. This would give you good performance, If you boat is rare or a one off then you'll have to work this out for yourself. If he boat turns into windward too much,then your mast needs to be more vertical if it wants to turn away or feels dead you may wish to tilt the mast further back.

    Almost certainly the forward shrouds should not be tightened all the way, if the boat rigging has been correctly made, shroud turnbuckles should be near the middle of their settings as would the forestay turn buckle.
    Remember if is quite likely that the forestay should be tight But not rock hard as the wire in the jib should be taking the strain while sailing to stop that sagging off.
    On the boats I have sailed the forestay and the rear stays are used to set the preferred angle of mast rake to get the magic distance. Once that is done the inner or forward stays are set just tight enough to keep the mast straight they are tight but NOT putting a huge pressure on.

    The backstay is in normal winds is set just tight enough to take the slack out. but as the wind increases you then start putting more pressure on the back stay which has the effect of putting more pressure on the forestay to keep the jib taught and bending back the mast top therefore dumping some wind out of the top of the main sail.

    Knowing your magic distance will be important to you if raise and lower your mast often, somehow stays and shrouds have a mystery habit of changing length on you when raised or lowered, I race my boats and that includes in one Annual race taking the mast down 4 times during the race !! After that race dimensions definitely need checking.

    Sorry for taking a few days to reply but I'm rebuilding my future racing boat which means I'll be having to re-find my "magic distance" as the boat will be 28 inches shorter.!
     
  12. philSweet
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    philSweet Senior Member

    Q, I don't think this sort of rig tuning is what the OP has in mind (but I could be wrong). In contrast to your experience, a typical cruiser might take his mast down once every ten years. His jib, flown on a cruising furler, might have a halyard tension that is all of 2% of the headstay tension when hoisted. Obviously, when you crank on 5000 pounds of sheet tension, this goes up. But for the furler to operate, the halyard's tension is usually kept low. Most cruiser masts are stiff. The range of mast rigidity seen on boats today ranges over a factor of 100. My spreaders are stouter than some masts on boats of similar size.

    The tension on the lowers does depend on rig specifics, but as a cruiser, I don't EVER want slack or reverse loading. My lowers have a pretension of about 40% the SWL for the wire. That's higher than most boats, But I can drop the boat sideways ten feet and not have the lee side go slack. Basically, as a cruiser, I am going to do just about the opposite of what you would do as a racer.

    As you said, In order to do this justice, we need to know more about the boat, the spars and rig, and how it will be used and maintained. The "magic distance" that minimizes the power draw of a cruiser's autopilot is going to be different from that which racers will use. Unless the OP wants to do can racing, rig tuning advice from racers is not going to help him very much. Racers benefit from having marginally stable boats and a busy crew. Cruisers trade off that last bit of performance potential to gain ease of handling and a steadier balance and greatly reduced maintenance.
     
  13. SailorStan
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    SailorStan Junior Member

    My boat is a Foxcub MK1. It is 18' long, has twin keels and the mast is deck stepped. The mast is 21', the spreaders a piece of tubing that goes straight through the mast.
    The boat is trailerable so once I have everything figured out I want to mark everything so that I can reset it each time I launch the boat.
     
  14. PAR
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    PAR Yacht Designer/Builder

    Stan, what you'll do is setup it up at the beginning of each season and if you're lucky, be able to keep the same settings during the warm months. In reality things stretch, so some periodic adjustment is necessary. How anal you are about this depends on how much you want out of her. Racers will check rig tensions before each race and make adjustments during the race. Casual sailors and cruiser will simply set it and forget it, until they notice something's not right. To get this in the ballpark, have a skilled sailing buddy help you set the rig up, after you tell him what you're after, then keep this in mind come next year when you have to do it again.

    [​IMG]
     

  15. The Q
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    The Q Senior Member

    There is a Foxcub 18 group of 427 members on Yahoo as the Owners association appears to have closed down.
    I think contacting them will give you any measurements / positions and tips that you Need rather than us here trying to second guess general advice for a class we may not know exactly.
    I have raced against one in my old Lysander 17, but never went on board it.
     
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