Backstay

Discussion in 'Sailboats' started by Lew Morris, Jun 26, 2004.

  1. Lew Morris
    Joined: Jun 2001
    Posts: 124
    Likes: 4, Points: 18, Legacy Rep: 92
    Location: Pismo Beach, Ca

    Lew Morris Industrial Designer

    My little McGregor Venture 17 needs a backstay.

    Actually, she doesn't need the backstay, I do... Fractionally rigged with no spreaders, and without a backstay, she is suitable for lake sailing but I'm now asking her to venture (no pun intended) out into the bay. With late afternoon winds touching 25k+ combined with swell, and wind waves, I'd feel a lot more comfortable with one. Maybe I'm being overly cautious, but when it comes to the sea I don't mind if anyone thinks I'm a wimp.

    So, the question is; do I just pick up the necessary hardware and rig it up, or is there something more specific that I need to consider? i.e., do I need to rig a crane off the masthead (my main has no roach)... backing plates and tying the stay to the hull seems prudent... total combined sail area is MAYBE, 150 sq. ft....

    Thanks all,

    Lew
     
  2. stew fl
    Joined: Jun 2004
    Posts: 8
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: florida

    stew fl Junior Member

    Lew,

    I learned how to sail on a venture 21, you might want to get your ruler out because I never heard of a venture 17 but I suppose they might exist.
    Steve would tell you that you need a naval architect for this job but I say get your drill out and go to work!
    You didn't say whether you wanted an ajustable backstay or not so I will assume not because you can always change out later.
    Get a padeye or something similar rated for around 500 to 1000 pounds and mount it in the obvious place, center on top of the flat part thats parallel to the water. Go to the local welding shop and get a piece of aluminum at least 1/8" thick to use as a backing plate , drill and thru bolt it with fasteners apropriate for the padeye.
    PS. don't forget sealer (3M 5200) but there ain't no wood core back there to rot any way.
    Call Layline or go to Boat US and get one of those
    adjustable things with all the holes in it or get a turnbuckle.
    The backstay it's self is a little more complicated nicopress fittings are OK for a small boat like your's but is the mast where you like it fore and aft wise, weather helm and all that, because you only have a few inches of adjustment to work with.
    Problem #2 is yes you probably need a crane as there is nothing up there but the end of the mast extrusion and unless there's a cast cap on it you don't have a servicable mounting point for the wire youre throwing up there.
    The wrap around type are easy to fabricate,see attachment.
    But you know! Steve is probably right the experts designed the rig and it ain't gonna bust unless you neglected to properly maintain and inspect it.
    And speaking of inspecting, look at that piece of garden hose your keel cable runs up thru, mine wound up wrapped around the lifting winch once as I was motoring up some shallow parts and it's a good thing it was shallow.
     

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  3. Jeff H
    Joined: May 2004
    Posts: 40
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Annapolis, Md

    Jeff H Junior Member

    I am not sure why you think that your Venture needs a backstay. In its normal configuation the shrouds are set aft to provide the necessary aft component to your staying. That is not an uncommon set up on a small fractional rig. One nice thing about that rig is that the mainsail is self depowering as the head of the mast sags off to leeward in a gust. On the other hand, the jib will automatically power up as the headstay sags which ends up reducing weather helm.

    Adding a backstay would reduce the amount that the jib powered up but would also increase the stresses in your rig, especially at the forestay attachment point which is a light weight RaceLite fitting and is not all that robust. It would also increase compression on your mast and mast support structure which also are not especially robust. Off hand adding a backstay does not seem like it would add a lot of safety or sailing ability to your boat, but would add cost, complexity and perhaps result in a boat that was less suitable to heavier going.

    You would probably need a masthead fitting that had a backstay attachment point and which had at least a minimal crane to clear the mainsail headboard.

    Respectfully,
    Jeff
     
  4. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 479, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I second what Jeff has had to say and would add the likelihood of ripping out the headstay fitting would increase rapidly. I'd also suspect the uppers would be close behind in coming apart, with the adding of a backstay.

    The rig on that boat was marginal at best, intended for light duty on lakes and rivers. If you intend to push the envelope in big water with a near shore boat, you'll have to face the issues associated with over driving an under equipped craft, past it's design limits.

    If you want to play in bigger stuff then put bigger stuff in your boat. Rig her with the next size up in stays, shrouds and hardware. Then you'll only have to worry about the light weight sails and stick giving up farther from shore then you'd like to paddle.
     
  5. SuperPiper
    Joined: Jan 2003
    Posts: 366
    Likes: 6, Points: 18, Legacy Rep: 58
    Location: North Of Lake Ontario

    SuperPiper Men With Little Boats . .

    Lew:

    I have a Sandpiper 565 (18'-6"OA). In a blow, the leeward shroud would go limp, the headstay would sag and the mast would pump. The rig needed more tension.

    I added backstays.

    I used 1/8" Vectra (which has a breaking strength close to wire) with a 3:1 tackle at the transom. The pumping action has stopped. The headsail is flatter and the boat points better.

    I believe that the backstays put less compression into the mast than would increased tension on the shrouds. The backstays are attached at a distance that is more favourable than the narrow shroud base. Backstays would be more efficient at keeping the mast from going forward than the shrouds which are located almost abeam to the mast base.

    I used 2 backstays because my little boat has a transom-mounted rudder.
     
  6. SailDesign
    Joined: Jan 2003
    Posts: 1,964
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    Location: Jamestown, RI, USA

    SailDesign Old Phart! Stay upwind..

    [quote = Stew fl] Steve would tell you that you need a naval architect for this job but I say get your drill out and go to work! [/quote]

    After reading PAR's description of the rig being marginal at best, it probably wouldn't hurt, but you have to balance cost against gain.

    And also upgrade the ballast to cope with the extra weight aloft, or you will be going into the bigger stuff with less stability than you had available in the small stuff. Never, ever, upgrade the tophamper without a corresponding increase in ballast. Of course, this will probably make the boat too heavy to perform anywhere near it's previous best. As Stew says, I would consult someone before throwing money at these changes. It may be cheaper to buy a different boat :)

    But then, I'm slightly biased...

    Steve
     

  7. Doug Lord

    Doug Lord Guest

    It would seem to me that the backstay would actually unload the mast in conditions in which the load is normally taken by the raked back shrouds. The raked back shrouds probably don't come back more than 5° or so and the angle from the masthead to transom on a Venture 17 would be substantially more than that.
    You wouldn't need a dual backstay; you could use a bridle with a block + cleat on one side(or just the simplest way since you really don't need much adjustment ). To avoid over stressing the rig don't adjust the backstay to have significant tension going upwind-just let it do its work downwind. You could seriously over stress the rig if you tighten the backstay upwind because you would be putting more tension on the forstay tang and forestay attachment point than it was designed for.As well as perhaps bending the mast enough so that the shape of the main is no longer satisfactory.
    But if you still have the original Venture 17 rig you should seriously consider replacing it with newer material and a better design which should reduce weight and improve safety in the "new" conditions you describe...(see Steve)
     
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