[Rhodes22-list] shroud tension jokes
Toad the Wet Sprocket
rhodes22-list@rhodes22.org
Tue, 20 Aug 2002 15:30:44 -0400
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<P>Roger,</P>
<P>So you have a total of 1800lbs of tension on all of your shrouds, not to mention the fore/backstay tension? Where did you come up with all of these figures? Are these the specs from Stan and the guys at GB? This all seems like quite a strain on the chain plates and alot of compression down through the mast into the hull. </P>
<P>Did you replace your rigging with larger cables or beef up the chain plate mountings? </P>
<P>Where can one buy the guage you have and a tape measure that measures to three decimal places? Is my boat supposed to bend up at the ends like a 22 foot banana too?</P>
<P> Sorry, I couldn't resist. I was in a goofy mood today. Honestly, where did you get these specs? </P>
<P><BR><BR><BR>Please respond to sprocket80@hotmail.com </P>
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<DIV></DIV>
<DIV></DIV>
<DIV></DIV>From: "Roger Pihlaja" <CEN09402@CENTURYTEL.NET>
<DIV></DIV>Reply-To: rhodes22-list@rhodes22.org
<DIV></DIV>To: <RHODES22-LIST@RHODES22.ORG>
<DIV></DIV>Subject: Re: [Rhodes22-list] shroud tension
<DIV></DIV>Date: Tue, 20 Aug 2002 07:56:38 -0400
<DIV></DIV>
<DIV></DIV>Jack,
<DIV></DIV>
<DIV></DIV>Here's a copy of the rig tuning procedure I use:
<DIV></DIV>
<DIV></DIV>The 1st thing you want to do is measure the length of the forestay on center
<DIV></DIV>from pin-to-pin. On my 1976, standard mainsail, Rhodes 22, this measurement
<DIV></DIV>is 333.625 inches. Write this number down because it is very important.
<DIV></DIV>If your forestay length is more than a couple of inches different than this,
<DIV></DIV>you might want to reset it 333.625 inches as a reasonable starting point.
<DIV></DIV>
<DIV></DIV>Now step the mast. Take the excess slack out of the forestay & backstays
<DIV></DIV>with the backstay adjuster. You don't want things real tight at this point.
<DIV></DIV>All upper & lower sidestays should be slack. Go to the base of the mast,
<DIV></DIV>pull a halyard taut along the mast & sight up the mast from the rear & from
<DIV></DIV>the side. Any deviation from a straight mast will show up as a gap between
<DIV></DIV>the mast & the halyard. There should be no observable bend or bowing in the
<DIV></DIV>mast. If there is, the mast may have been dropped & bent at some point or
<DIV></DIV>may have some other problem. You should call Stan at GBI & he will be able
<DIV></DIV>to help you work out your problem.
<DIV></DIV>
<DIV></DIV>I like to use a Loo's tension gage. The model 91 is the appropriate range
<DIV></DIV>for the Rhodes 22. Remember to always measure the tension at the same
<DIV></DIV>relative position on each shroud every time. On Dynamic Equilibrium, I
<DIV></DIV>have marked these measurement points with little spots of paint on the
<DIV></DIV>wire right at my eye level.
<DIV></DIV>
<DIV></DIV>The upper sidestays are adjusted next. Raise a tape measure up the mast on
<DIV></DIV>a halyard. Measure to the same point on each side of the boat. I like to
<DIV></DIV>use the edge of the toerail right next to the sidestay. Tighten the
<DIV></DIV>turnbuckles a little at a time on each side to adjust the upper sidestays
<DIV></DIV>until both sides are the same length +/- 1/4" & tensioned to approximately
<DIV></DIV>300 lbs +/- 5%. This procedure assures the top of the mast is centered in
<DIV></DIV>the boat & the upper sidestays are tensioned equally port & starboard.
<DIV></DIV>
<DIV></DIV>What you do next depends upon whether your boat has the IMF mainsail or a
<DIV></DIV>conventional mainsail.
<DIV></DIV>
<DIV></DIV>On an IMF mainsail boat, I would adjust the 4 lower sidestays so they were
<DIV></DIV>all approximately the same tension. I would start with approximately 200
<DIV></DIV>lbs +/- 5% on all 4 lowers. This is not a lot of shroud tension. Check for
<DIV></DIV>mast straightness with the halyard again. You want the mast to be straight
<DIV></DIV>in order for the IMF furling mechanism inside of it to be able to turn
<DIV></DIV>without binding &/or excessive wear on the bearings. Minor bending or
<DIV></DIV>bowing can be taken out with the lower sidestays. However, I would call
<DIV></DIV>Stan at GBI if I couldn't get the mast to straighten out with a difference
<DIV></DIV>of about +/- 15% on lower sidestay tension.
<DIV></DIV>
<DIV></DIV>My Rhodes 22 has a conventional mainsail. I have a very roachy fully
<DIV></DIV>battened mainsail which has been cut to respond to mast bend. I have my
<DIV></DIV>backstay adjuster set-up to adjust quickly from the cockpit with calibration
<DIV></DIV>marks on the line.
<DIV></DIV>
<DIV></DIV>Tighten the turnbuckles equally & a little a time on each side to keep
<DIV></DIV>things reasonably centered. I adjust the forward lower sidestays to 400 lbs
<DIV></DIV>+/- 5% of tension, and the aft lower sidestays to 200 lbs +/- 5% of tension.
<DIV></DIV>Then, check for mast straightness with the halyard. Believe it or not, the
<DIV></DIV>standard mast on the Rhodes 22 is such a stiff telephone pole that, at 200
<DIV></DIV>lbs differential tension on the lowers, there will be a barely detectable
<DIV></DIV>fore/aft bend in the mast with no sails set & the backstay adjuster slack.
<DIV></DIV>At 400 lbs of tension on the lower forward sidestays, when the backstay
<DIV></DIV>adjuster is tensioned, primarily only the upper half of the mast is pulled
<DIV></DIV>towards the stern. The forestay is tightened & the mast is bent at the same
<DIV></DIV>time. Both actions are exactly what you want to obtain proper sail shape in
<DIV></DIV>a high wind situation.
<DIV></DIV>
<DIV></DIV>Now go out sailing. On a close hauled course, put up enough sail to heel
<DIV></DIV>the boat over about 15-20 deg. Make certain the rudder blade & centerboard
<DIV></DIV>are all the way down. On my Rhodes 22, the above tension settings cause the
<DIV></DIV>mast to remain straight & more or less centered in the boat. The primary
<DIV></DIV>thing to check is the upper sidestays. On my Rhodes 22 with the above
<DIV></DIV>unloaded tension settings, at 15-20 deg of heel, the windward upper sidestay
<DIV></DIV>should have about 450 lbs tension & the leeward upper sidestay should have
<DIV></DIV>about 150 lbs of tension. I have my upper sidestays set-up such that the
<DIV></DIV>leeward upper sidestay tension drops to 0 lbs at about 30 degrees of heel.
<DIV></DIV>At this point, the windward upper sidestay will be under about 600 lbs
<DIV></DIV>tension. Note, normally the stays are set-up to give proper shroud tension
<DIV></DIV>& the correct amount of weather helm with full sail set. This tends to
<DIV></DIV>limit the weather window in which you can do this sort of tuning.
<DIV></DIV>
<DIV></DIV>When all sails are properly trimmed & the boat is "in the groove", there
<DIV></DIV>should only a slight amount of weather helm. If there is a huge weather
<DIV></DIV>helm, or neutral, or lee helm; then, you need to adjust the rake angle of
<DIV></DIV>the mast. If you have neutral or lee helm; then increase the forestay
<DIV></DIV>length. To get rid of excessive weather helm, shorten the forestay. The
<DIV></DIV>balance of the boat is very sensitive to this mast rake angle, so change it
<DIV></DIV>in increments of about 1/2" at a time. Note, a slight amount of weather
<DIV></DIV>helm
<DIV></DIV>is desirable because it provides feedback to the helmsman, thus allowing
<DIV></DIV>him to steer a better course. Excessive weather helm tends to tire the
<DIV></DIV>helmsman out.
<DIV></DIV>
<DIV></DIV>Once I'm happy, I lock the adjustment in place by taping the lock nuts on
<DIV></DIV>the turnbuckles. I find I only need to do this adjustment once. The
<DIV></DIV>Rhodes 22 is such a strongly built little boat that nothing ever seems to
<DIV></DIV>stretch or bend. I do check the side-to-side upper sidestay length at the
<DIV></DIV>beginning of every season; but, it's never changed in the 13+ seasons I've
<DIV></DIV>been measuring it. Trailering set-up only involves adjusting the lower
<DIV></DIV>sidestays since the rest are not disturbed.
<DIV></DIV>
<DIV></DIV>As far as rig tension settings on the trailer vs. off the trailer, I've
<DIV></DIV>found the
<DIV></DIV>only rig tension adjustment that significantly changes is the backstay
<DIV></DIV>tension.
<DIV></DIV>You can set the tension on the rest of the standing rigging according to the
<DIV></DIV>above procedure on the trailer. It will be very close to optimum when you
<DIV></DIV>get the boat in the water, certainly good enough to do the on-the-water
<DIV></DIV>fine tuning described above.
<DIV></DIV>
<DIV></DIV>FYI, I slack off on the backstay tension when Dynamic Equilibrium is not
<DIV></DIV>being sailed. As I mentioned above, the backstay adjuster has sufficient
<DIV></DIV>power to affect the shape of the hull. Greatly exaggerated, imagine the
<DIV></DIV>ends
<DIV></DIV>of the hull being pulled upward like a 22 foot long banana when the backstay
<DIV></DIV>adjuster is tight! There is no sense leaving the hull & rig under that kind
<DIV></DIV>of
<DIV></DIV>stress when the boat is not being sailed.
<DIV></DIV>
<DIV></DIV>Jack, I hope this description of rig tuning helps you. Good luck!
<DIV></DIV>
<DIV></DIV>Roger Pihlaja
<DIV></DIV>S/V Dynamic Equilibrium
<DIV></DIV>
<DIV></DIV>----- Original Message -----
<DIV></DIV>From: "Jack Goldberg" <J_GOLDBERG@HOTMAIL.COM>
<DIV></DIV>To: <RHODES22-LIST@RHODES22.ORG>
<DIV></DIV>Sent: Monday, August 19, 2002 7:47 PM
<DIV></DIV>Subject: [Rhodes22-list] shroud tension
<DIV></DIV>
<DIV></DIV>
<DIV></DIV>> This list has been helpful in the past, so I'll come to the trough of
<DIV></DIV>> knowledge to feed again.
<DIV></DIV>> I noted with interest the thread about the mast plate bolts coming loose
<DIV></DIV>and
<DIV></DIV>> the response with regard to the tension of the shrouds. My 84' has a
<DIV></DIV>> standard main. When I bought the boat this spring, the shrouds were very
<DIV></DIV>> loose (obout 3 inches of play from side to side at about 3 feet from the
<DIV></DIV>> deck. The guy I bought the boat from said that was OK, but now I'm
<DIV></DIV>worried.
<DIV></DIV>> Is there a spec' on how tight (or loose) the shrouds should be under no
<DIV></DIV>> load?
<DIV></DIV>>
<DIV></DIV>> Jack Goldberg,
<DIV></DIV>>
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