Conference unifix::sailing

    Very interesting Gene, now a couple of questions.
     On a cruising boat which wants good performance, is a tight backstay
     and forestay adequate providing one adjusts the jib luff tension
     depending on the wind?
    
    What is the effect on a mast with double lowers, i.e. forward and aft
    lowers, if a backstay adjuster is added.
    
    Bill

    Bill,
    
    I'm a cruiser, not a racer.  On Wednesday nights we bring my boat to
    the vicinity where racing is taking place.
    
    I can relate to a lot of what Gene said in .0.   One night last year,
    Gene was out with us aboard my boat.  I had set the head stay tension
    according to the initial setting recommendation from my Loos tension
    gauge instructions.  The wind was high teens, or low twenties.  The
    seas were sloppy, and Gene was trying to steer the boat upwind.  With
    the backstay slack, we still didn't have enough head stay sag to give
    us a decent groove to work with, using the #3. 
    
    This year I left the head stay significantly looser.  Almost loose
    enough to make me squeamish.  The first night Gene came out with us, he
    loosened the head stay a little bit more.  And was able to get the tell
    tails all streaming nicely.  The back stay adjuster can be used to
    tighten the head stay when the wind pipes up.
    
    As far as adjusting the halyard tension to serve the same function, I
    think the analogy might be similar to ignition timing and octane in a
    gasoline engine.  You can help compensate for low octane by retarding
    timing, but you won't get all the performance which was built into your
    equipment.  By being able to adjust your back stay you just get the
    ability to do a little more with the wind available.  In light air this
    may make the difference between sailing and powering.
    
    djc
                                                                   

    re .1
    
    Jib halyard tension controls the position of the maximum draft along
    the locus of cords connecting the jib leech and luff.  Imagine a plane
    parallel to the surface of the water intersecting the jib at the luff
    and leech.   The portion of the jib intersecting this plane describes a
    curve whose point of maximum depth can be adjusted by applying more
    halyard tension.  More tension moves this point closer to the forestay. 
    In a breeze this is needed to offset the stretch near the leech since
    that part of the jib is unsupported.
    
    The backstay adjuster controls depth in a totally different plane. 
    Imagine a plane perpendicular to the surface of the water passing
    through the jib at any point.  We get a curve where the plane and jib
    intersect running roughly vertically.  It's the depth of this curve
    that the backstay adjuster controls.  More tension = less depth.
    
    If there is too much sag no amount of halyard tension will improve
    pointing until the halyard starts to support the rig rather the
    forestay.  But by that point, the jib luff will have been irreparably
    stretched out of shape.  If there is too little sag no amount of
    halyard tension can get enough draft forward to compensate.  Backstay
    tension and halyard tension are pretty much independent.
    
    On a cruiser, backstay tension should be adusted as described in .0
    except that the I'd do it for the average wind with a jib appropriate
    for that wind speed.  Then pin and tape the turnbuckle and forget about
    it.  As the wind comes up, you'll change to a smaller sail and that'll
    offset the increased jibstay sag.  
    
    Double lowers are normally looser than the uppers and should not
    normally affect the function of the backstay adjuster.  If they were
    real tight, they'd induce some mast bend as the backstay is tightened
    but that shouldn't be the case unless you normally sail in high winds. 
    And if you were in high winds, you'd probably want a bit of mast bend.
    
    -  gene

    I have become a big believer in adjusting backstay tension constantly
    to adjust to the conditions.  Now I'm talking about a fractionally
    rigged boat where most of the movement is done via the runners.  The
    permanent backstay does no more than control the very top of the main. 
    The headstay tension or sag is controlled by the runners.
    
    For cruising this is not too relavent.  For racing it is crucial.  We
    punish our driver by narrowing his groove to the minimum he can handle
    when we need to point up on somebody.  You can't maintain this level of
    concentration for very long, however, and you must choose your time to
    use it.  BTW, our backstay eases out 18 inches on downwind legs to the
    point where we have to put a halyard to the point of the bow because
    our headstay is flopping around uselessly.
    
    Dave

    On Quokka, they have rigged a thin piece of kevlar line between the end
    of the permanant backstay and the purchase blocks used to tighten it.
    
    Apparantly, when they they bore away from a windy beat ( runners and 
    backstay tight on ) onto a run ( runners eased, kite up ) they used
    to forget to dump the backstay, resulting in huge strains on the top
    section of the mast. Ideally, the kevlar line will break before the
    mast.
    
    I totally agree with Daves note about the importance of getting
    the tension right for the conditions. Even the slowest cruiser will
    improve its upwind speed, in moderate to strong wind, by having a tight 
    forestay. Being able to ease it off in the light stuff is not so
    important for cruisers.
    
    Chris
    

    Quokka is a One Tonner just like Harrier is.  The problem with the perm
    not being released on the turns to the downwind leg is a problem.  We
    have the same rig where the kevlar line (very thin) will break before
    the top of the mast is pulled off!
    
    BTW we also play the checkstays a lot.  We have internal controls in
    the mast that lead right to the main trimmer for easy adjustment.  On
    Wildside the controls were blocks on the check itself controlled by the
    runner person.
    
    Dave

>    We have the same rig where the kevlar line (very thin) will break before
>    the top of the mast is pulled off!
    
    How thin ?, and has it ever broken, either when it is meant to, or
    otherwise.
    
    On Quokka, we rigged a very thin bit, and on a windy overnight race, 
    which was sailed most of the way with a reef or 2, the kevlar broke
    because the backstay was flogging loose. The owners have now replaced
    it with a thicker bit, but I am not convinced that it will now break
    when required.
    
    Regarding checkstays, the local handicap system ( CHS ) attempts to
    penalise lightweight rigs, and it does this by counting the number of
    spreaders, and whether or not the boat has runners or checkstays. This
    has led some people ( including Quokka ) to remove their checks, but
    last weekend the owner was looking a little alarmed at the amount of
    panting in the lower section, and is now having second thoughts,
    particularly with the Fastnet coming up. ( unfortunately, I won't be on
    board for this, due to lack of leave ).
    
    Chris
    
    

    Our kevlar line is probably 5/16 inch line.  Maybe 1/4.  I'll check.
    
    How can you sail without checks!?!?!  On our rig we'd blow it on the
    first real windy upwind, lumpy leg.
    
    How can you feel unfortunate to not be doing the Fastnet?  I heard that
    the One Tonners on the Admirals Cup teams were all going to start and
    then drop out right away so no team has the advantage, but no boat
    designed for short course, wet, sailing has to endure that race.
    Sounded like a hell of a good idea to me!
    
    Dave

>    How can you sail without checks!?!?!  On our rig we'd blow it on the
>    first real windy upwind, lumpy leg.
    
     I don't think they have had one of those since they removed the
     checks ! . It certainly wobbles a bit now and I think the owner may
     be having second thoughts.
    
>    How can you feel unfortunate to not be doing the Fastnet?  I heard that
>    the One Tonners on the Admirals Cup teams were all going to start and
>    then drop out right away so no team has the advantage, but no boat
>    designed for short course, wet, sailing has to endure that race.
>    Sounded like a hell of a good idea to me!
    
     I heard that too, but I am sure it won't happen in practice.
    
     My concern would not be getting wet and cold, but getting bored. There
     is little enough for a crew of 9 to do on an inshore race ( OK, you
     need 8 to gybe the kite ), but on the Fastnet some of the legs are
     over 150 miles. In 1987 I did the race in a 30 footer and we changed
     sails twice between the start and the Fastnet rock ( about 400 miles)
     once putting the kite up, and once taking it down. I think we also
     tacked about 3 times. This was OK with 5 people, as you had to share
     the steering, nav, cooking trimming etc, but with 9 or 10 it would
     have meant of a lot of time spent admiring the scenery.
    
     I guess that it could be pretty unpleasant, but I will a bit jealous
     when I sit at home watching all my friends setting off. In spite of
     its reputation, the Fastnet is often a light weather race and sunburn
     and shoratge of food is as likely to be a problem as wind and waves.
    
     Chris.
    

    
    	I believe that here in New England, the PHRF allows checks without
    any rating hit, but any or all running rig out back is accounted for.
    Plus spreaders. I don't think it's meant as punishment, rather that
    Big John knows that such setups aren't there for looks. Seaworthyness 
    is up to the owner.
    Scott.

    I have a question about backstays. If you have a mainsail with a large
    roach, so that a single backstay doesn't give enough room for the sail
    to fit under, can you fit a pair of stays, one on each side of the
    sail? There would have to be a way to let one loose, and there would
    still need to be sidestays to handle the situations where you don't
    have the correct backstay tight at the needed time, but if the main
    thing you need it for is to hold up the spinnaker and main on a run,
    you might be able to cope with that kind of setup.
    
    What drives this is the possibility of using a more flexible hull. If
    you rely on the shrouds to support the main and spinnaker then the hull
    needs to be extremely stiff, but if you could get additional support
    from a backstay it might give enough reduction in hull load to be
    worth it.
    
    Is this already figured out and I just don't know about it?
    
    Doug.

    One of Australia's America's Cup boats had a real flexible hull earlier
    this year.  It's probably a popular dive site nowadays.  
    
    Flexibility and longevity probably don't go well together when mixed
    with waves and winds.
    
    Why would you want a flexible hull?
    
    djc
    

This sounds like a running back stay.  These were used alot with gaff rigged
boats.  The have a very stiff and long roach (the gaff).

The old wood boats had flexing trouble (limited the length of a warship), and
often literally rotten running rigging.

I have never used one, so I can not tell you just what is involved.

Doug

    I'd be sorta carefull and talk it over with the boat designer. In the
    past couple of months there have been a couple of articles on some of
    these new ultralight racers with bendy masts blowing up because the 
    tensions of the backstays not being done exactly correct in blustery
    conditions.
    
    I take it you are talking about a full length batten set. I have
    noticed on the new ILC 40 and Andrews boat the they only have 2-3 ft
    battens in the back of the main, which I would expect to easily pop
    by except on really light air days.  And they seem to be low on the
    main and not near where the roach is really pronounced.
    
    Another trick would be to build the backstay out of coated wire or
    a piece of kevlar cored line. This may keep the chafing to a minimum.

    Actually what brought this up was a discussion of old 505s that
    had substantially softer hulls than the more recent ones. Since the
    505 sail is designed for shrouds-only standing rigging, it has
    a lot of roach. There is one (top) full length batten but that's not
    really the problem--both the boom and the sail are way too big
    for a fixed backstay. The class rules, however, allow virtually
    any kind of standing rigging, so one possibility might be to
    use the standard sail shape but add more support without overloading
    the hull.
    
    Apparently when the 505 was designed (early 1950s) the minimum hull
    weight was set so low that a lot of flexible boats are out there.
    During the 1960s the Australians worked to come up with a rig that
    would work with the flexible hulls, but the Americans worked on getting
    very rigid hulls and then ended up with a very tight rig. Now everybody
    is using the tight rigs and there are several thousand older boats
    out there that aren't competitive any more. Given the chance of buying
    a new boat for >$10k, or finding an old one for a grand and adding
    a backstay, I was thinking that the latter might be a bit more
    optimal for my extremely limited budget...
    
    How does a running backstay work?
    
    Doug.

    My Soverel thrity three has running backstays, checkstays, a permanent
    backstay and a huge roach.
    
    Dont worry about clearance. The wind, unless its real light, will flip
    the battens past the backstay when you tack or gybe, especially as you
    usually let the traveller down to build a little speed before pointing. 
    
    The sov33 is a 15/16th rig. My Runners are designed to support the
    headstay. You crank them up with a winch accoridn to conditions. Light
    air/waves, you relax them a bit to deepen the draft of the main for
    power. Flat water/heavy air crank it up to reduce headstay sag and get
    the boat pointing. Flattening the jib helps keep the boat on its feet.
    
    The backstay controls the upper third of the main. I usually run it
    completely off. this means my upper spar is straight and the main has
    full draft up high. Once the wind is over 20kn true, and the blade jib
    is up, I'll crank in backstay to go upwind and dump it on all other
    headings.
    
    The checkstays configure the main for power or pointing. They do not
    effect the jib, which makes them valuable. In a reach of any type, I
    crank them in hard. This will pull the center of the mast back to
    vertical and add depth to the main. It powers up the boat incredibly.
    Just like hitting passing gear. In a spinnaker reach where its blowing,
    sometimes a powered up main is just too much. So you dump the
    checkstays and crank in the backstay and drop the traveller down. The
    main is coasting, making it easy on the helm. A go-fast combo.
    
    The hull must be stiff, stiff, stiff, or none of this stuff works worth
    beans. What's the good of having adjustments that working in inches if
    the hull just gives back what you pull out of the rig.
    
    The backstay is a 24:1 multiplier tackle, The checkstays are 6:1 and
    the Runners are coupled to Lewmar 16 winches. The spar has an 18" arc
    in it at full deflection. Of course it is 50ft long so that is not as
    much as it seems. 
    
    Hope this helps...
    

    Forgive the mistypes in the previous. Word 6.0 tools have made me
    lazy..... Runners deep the draft of the jib (not the main) in the
    example used
    

    Ok, this helps. I'm still confused about where the lines connect. Also,
    what do you do downwind? Or is this all related to adjusting sail shape
    on the wind?
    

    re .18   let the backstay out along with some halyard and make everything
    ugly and fast going downwind.
    
        When I set my backstay presure, I put about 1/3 of it on and then
    crank in my jib halyard to the tension I need. That way when I yank in
    the backstay adjuster, I do not tear the jib/genny by overstretching it
    (trick I learned from North Sails sailing video).
    
        I only crank in my backstay when the wind goes above 15knts and I
    am going upwind, or I need so control on a tight reach. It is amazing
    how a bit of mast bend flattening the sails will make the boat not
    only faster, but much easier to control.  I only have a 4:1 but it is
     used on a johnstone split backstay adjuster, so it really is much
    higher than that. Haven't gotten around to marking the bend on it yet
    with a plumb bob.
    
        Just before the leeward mark, reset backstay tension, crank up the
    halyards, and get ready for going hard on the wind again. Ain't rac' n
    fun  ;>)   ;>)
    
         john

    The backstay attaches to the masthead crane at the very top of the
    mast. The Runners attache about four feet down and directly opposite
    the heastay (15/16th frac rig), the checkstays attach to the mast about
    fifteen feet down from the headstay.
    
    I set my jib halyard tension to a premeasured mark on the foil with NO
    tension on the sheet. When hundreds of little wrinkles show up along
    the luff from windpressure (halyard stretch) its time to downsize. My
    runner tails are marked for 10kn, 20kn and 30kn with corresponding marks
    on the checkstay tails. This is course adjustment for tacking. Fine
    tuning comes after the boat gets up to speed. When the mainhalyard
    stretches a little, the cunningham takes up the slack and it also pulls
    the draft forward powering up the main in a chop.
    
    In addition to dumping the backstay for downwind, I have two sheet
    stoppers on the mainhalyard. I can preset the easement by slipping a
    couple inches of slack between them, then round the mark, pop the lead
    spinlock....pow! beautiful downwind main.  The runner stays dialed in
    to offset the spinnaker's load. checkstay comes in hard, outhaul is
    dumped to deepen the shelffoot.  
    
    Yes, it takes seven people to race a soverel thirty three hard. And the
    "hotbox" is like playing the piano, four winches, eleven sheetstoppers,
    cunningham and vang. whew!
    

    Class rules will probably prohibit the use of running backstays on a
    505.  If you want to see how they work on a small boat, take a look at
    a Star boat.  A very large main supported by runners.
    
    To solve the soft hull problem most cost effectively, try having the
    sailmaker cut the main with a tigbter leech and the jib with more luff
    sag.  These changes may allow the sails to better accomodate the
    inevitable leeward sag in the rig.
    
    Or some DIY epoxy and kevlar/carbon-fiber work can stiffen the old
    hull.
    
    - gene

    Ok, thanks. Is there one runner on each side of the boom? What happens
    to the leeward runner when the sail is out on a run?
    
    Doug.

    Two runners........One for each side. The leeward side gets eased. A
    lot. My runner tails are fifty feet long. Of course it is two to one
    tackle, but still the block must follow behind the boom all the way to
    the shrouds.
    
    When I single hand, daysail, I go no-jib and use bungee cords to the
    keep the runner blocks tied to the lifelines up forward. This way I can
    manuever the boat like a monstrous dingy. When there is air enough
    (20+kn), its a blast. For single handling, cruising, you plan tacks
    waaaaay ahead....settle for a darn sloppy one and then:
    
    		put the helm over and tack the boat
    		neutralize the helm and tie it.
    		release and trim the jib on new side
    		crank in the new runner, dump the old
    		lift the traveller
    		reset the helm for balance
    		fine trim everything
    		go get a beer.
    
    

    Ok, now I think I get it. Thanks very much. Whether it applies
    to 505s is somewhat questionable, obviously... but I do think the
    505 class rules are pretty loose in the rigging department (pun
    intended...)
    
    Thanks.
    
    Doug.