Index

SJ23 Standing Rig Tuning and Sail Setting Guide.

INDEX - Rig Preparation, Mark TB, Rig Tension, Loos Gauge, Sail Trim,

"The sails for the San Juan 23 have been developed using primarily our proven designs from the San Juan 24.  Although many San Juan 23 sailors are not interested in racing, most of you would still like to get maximum performance while cruising and the occasional race that many are likely to enter.  Here are some ideas that will help you get the maximum performance from your boat and sails."  Don Clark.

RIG PREPARATION - The San Juan 23 is designed to have up to 12" of rake in the mast when floating level on her waterline.  This is an approximate measurement and you will be in the ballpark by tightening the factory backstay so 1/2" of thread is showing on the top of the turnbuckle barrel.  Then adjust the forestay turnbuckle for the proper head-stay sag, approximately (5-6)" when sailing to weather in a medium breeze. 
- You can also determine the mast rake by lowering the main halyard to the deck with a length heavy of chain on the end.  Measure how far aft the end of the chain is from the mast base.  Subtract 2" to allow for the mast head sticking out.  Panache's mast is raked at ~8".
- If a bucket full of water is placed at the base of the mast and then the chain is lowered into the water, the halyard will hang vertical with the water dampening movement of the line due to windage.  Use a long thin line on the end of the hoisted halyard to further reduce the effects of the wind.

The most accurate method to ensure the mast is perpendicular (lateral) to the hull is to hoist a light steel wire, Dyneema or measuring tape from a secured main halyard.  Extend the wire so it just touches the starboard toe rail, adjacent to the chain plate.  Then touch the wire to the port toe rail, adjacent to the chain plate.  If the wire just touches either toe rail without pulling the wire down then the mast is perpendicular to the hull.  Adjust the upper shroud turnbuckles to correct a lean. 
- If you are not that concerned about sailing performance, use just the main halyard from the mast head since it stretches very little.  However, it does sag which you will have to account for. 

Once the mast is perpendicular adjust port and starboard turnbuckles the same amount, +1/2 turn & -1/2 turn, so the mast stays perpendicular.  Final tension adjustments can be made while under sail which is most easily done by adjusting the leeward shrouds, tacking, looking up at the mast, tacking, etc. 
- The upper shrouds support most of the weight.  The lower shrouds keep the mast straight when the boat is heeled.

The shrouds should be fairly tight, so the leeward shrouds just start to loosen when the boat heels 20⁰.  (This is equal to about 400 lbs as measured with a tension gauge).  Keep in mind that 1x19 SS wire or the fittings do not like to be shock loaded which is why it is so important to tension the shrouds correctly.  Sight up the mast and adjust the lower shrouds to give a straight mast or a slight amount of sideways bend to leeward at the top. 
- It should be noted that the final tension adjustment should be preceded with static tuning of the mast.  Also see Tech Tip F24, Rig Tuning.

MARK THE TURNBUCKLES - For all of you sailors who seasonally launch your boat, don't consider yourself done after the initial mast tuning.  Since 1x19 SS wire stretches with time you should repeat this procedure in about a week or after a few sails and review it occasionally during the year.  Once you have tuned the rigging to perfection, wrap tape around the exposed threads on each turnbuckle, adjacent to the lock nut at the end of the barrel, thereby marking the position of the barrel.  This is the easiest and quickest way to duplicate your settings on a turnbuckle.  This visual feedback is confirmation to a force that is easy to measure if you have a Loos tension gauge.  Of course, marking the turnbuckles with tape is just as useful to those who trailer launch their boat each time you go sailing. 

The alternative to using electrical tape is to use a dial or digital calliper to measure the distance between the threaded studs of an open turnbuckle.  Ever since I learned how critical rig tension is to sailing performance, I use both of these techniques on Panache.  It really pays in the performance department.

RIG TENSION - The SJ23 is e/w closed barrel turnbuckles from the factory.  For this reason a turnbuckle must be loosened to measure how much thread is screwed into the barrel.  Maximum strength is achieved when all the barrel thread is screwed over the toggle thread.  An equal amount must be screwed over the top and bottom threads. 
Consider the following when tensioning standing rigging.  In general, wire is tensioned to about 5% of it's breaking strength when most of the sag is removed.  It is tensioned to 10% when it first produces a low frequency musical note when struck with a metal object like a wrench.  This is the desired tension.  CLARK SAILS.  TOP

Set Rig Tension With a Loos Gauge - "I have used a "Loos" gauge for all our sailboats.  There used to be two models, one for smaller gauge wire and the pro model for big boat wire.  Today there are several models so use the gauge that matches the wire size on your boat.  The LOOA91 or LOOPT1 gauge fits (3/32 to 5/32)" wire, which is suitable for the 1/8" wire used on a SJ23.  If you have the correct model for your boat then the shrouds and stays will fit in the measurement slot.

• The wire size tension ratings are on the face of the instrument.  A measured number in these columns equals pounds of tension.  Set the rigging to 10% of the breaking strength of the wire.

• Now that we have covered most of the technical BS here are the settings that work on my 1982 SJ23.
  - 28 lbs on the upper shrouds.
  - 26 lbs on the lower shrouds.
  - 24 lbs on the forestay.
  - 22 lbs on the backstay.

• Before adjusting anything you should lightly tension all wires, center the mast side to side, set the mast rake and then slightly tension the forestay/backstay to the point of about 3" of sag in the forestay with slight hand pressure.  When you tension the shrouds always sight up the mast kerf (mainsail slot) to ensure the mast is straight.  Sometimes you can turn one of the upper turnbuckles too much and you can put a sideways bend above the spreaders.  Similarly if you turn one of the lower turnbuckles too much you can put a sideways bow in the middle of the mast.

• I find I can adjust 1 full turn on each turnbuckle until I achieve about 3/4 of the tension I want and then 1/2 turn until done.  After the shrouds are done, tension the forestay and backstay equally to maintain mast rake until the forestay is about 24 lbs and when pressure is applied by hand you have 3" of deflection with moderate hand pressure.  I have a split backstay so I can run a little less tension in the forestay and then tighten it up with the adjuster for stronger winds.

Now, all this may seem to be a lot of technical mumbo jumbo but the boat really responds MUCH better if you take the time to do this.  The first time is a PIA but subsequently it will take very little time to keep it in tune.
I set the mast rake with the boat in the water at the dock with the boat loaded as it would be when sailed.  After you tension the rigging it will change very quickly with a strong blow so you should redo the tensions to the original settings.  After the second setting the tension will hold nicely for the remainder of the season.  If you find a wire has changed a lot the next time you set it then you should look for a broken strand in that wire or a bad lock nut.  Pin all turnbuckles when done and sleeve or tape the pins.  I use 3/4" schedule 20 PVC tubing over my turnbuckles to protect the sails.  These tubes are 2' tall and vent nicely.  You can buy it at a hardware store.

There are as many methods of setting wire tension as there are sailors.  I have found this works very well for me over 6 different boats.  Good luck and email me if you have a question or problems."  Ray Bowles  TOP

Set Rig Tension Under Sail - "Panache in cruising mode has 70 lbs of ground tackle in the anchor locker, 10 gallons of water in the tank under the V-berth, 3 gallons of flush water in the head, some stuff is lying on the V-berth, a 50 lb battery under the starboard settee, 2.5 gallons gas in the port cockpit locker and a 70 lb outboard on the transom.  She floats level on her lines with the turn of the transom about 2" above the surface.  The mast has ~9" of rake, is equipped with roller furling on a 5/32" forestay, 5/32" shrouds, 5/32" back stay with tensioner, the center board usually operates vertical or just aft of vertical resulting in a light feel at the helm.  If the Tiller Tamer is locked she can maintain her heading provided I don't move in the cockpit. 
A sail and tune session with some buddies in 2018 demonstrated something I learned.  When the shroud tension was tightened as per Clark's recommendation, Panache could point 5⁰ higher and sailed livelier after the turnbuckles were tightened only one turn.  This was reported by an experienced sailor who was on the helm but had never sailed an SJ23.  It demonstrates how effective correct tension is as also reported above by Ray."   Bob Schimmel  TOP
 

Mainsail Trim - Since it is possible to induce only a small amount of mast bend, the luff is cut fairly flat and shape is produced by broad seaming the Dacron cloth.  As the wind increases, pull the Cunningham down to move the draft forward to 35-40 % back from the mast.  You'll find that by removing the horizontal wrinkles in the mainsail luff you'll be very close.  The outhaul should be adjusted so the sail has 6" or so of belly in light air while sailing upwind and downwind in most airs, and pulled all the way aft as the wind increases and the boat heel approaches 20⁰.  Trim the mainsheet so that the uppermost batten is almost parallel to the boom or slightly falling off to leeward.  A tell tale at the leech of the top batten can tell you whether the sail is sheeted too tightly and stalled up there.

Jib and Genoa Trim - The 110% jib should be used in a breeze that produces 20⁰ or more of heel.  The mainsail may be reefed according to the wind strength, however the SJ23 should always be sailed with <25⁰ of heel.  (The pulpit forward leg is vertical).  The genoa will be happy if the leech is sheeted to 3-4" outside the spreader and the foot is just inside the lifeline on a beat, being careful not to pinch high which keeps the boat driving hard.
- One method of depowering the jib is to move the sheet lead farther aft to let the top of the jib twist off, and/or release the mainsheet a bit, even to the point of luffing.
- If you have a split backstay, this is another tool for affecting the jib/main relationship.  Starting in a lighter breeze with the backstay fairly loose, halyard fairly loose, the first trim increase with wind increase would be a little more halyard tension .  Look at the jib/spreader relationship that changes with only a slight addition of more halyard tension: the slot closes up.  Get a little puff, and the slot opens up.  More backstay: slot opens up.  More halyard, slot closes.

Sheet Tension - Sheet tension and the angle of the sheet leads should be adjusted so the sail luffs evenly top to bottom when sheeted in for windward work.  Generally the genoa should be sheeted so the leech is 2" or 3" off the spreader and the body of the sail should parallel the outer shroud from the spreader to the chain plate.  It may be sheeted more tightly for flat water.

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