SJ23 Tech Tip F06, (Updated 2024-06-16) Art Brown & Bob Schimmel

Index

Jib Sheet Tracks.

INDEX - Deck Track, Extend Track, Bend Techniques, Cabin Mount,

One of the reasons why I bought a San Juan 23 is because it can tack through ~450 and track straight in a lumpy seaway without loosing headway like my previous boat did with its ballasted swing board.  Although even an SJ23 has its limits.  Tacking and tracking are both valuable performance assets when the homeward leg is upwind!  To get maximum upwind drive from the jib, the sheeting angle must be correct, both fore/aft and athwartship.  A track installed on each side deck can ensure both.  However, I usually release the jib sheet a tad to create slightly more draft for more lift that helps the boat go faster.  While the operating manual suggests attaching the jib sheet block to the toe rail, I find that location too far outboard for close haul sailing.  If the track is full 6' length, from chain plate to cockpit coaming, the block can be slid fully forward for the storm jib, middle for the 110% jib or further aft for the 135% jib.  The 150% jib is sheeted to the cockpit track.

NOTE:  "There are limits to increasing boat speed or arriving at your upwind destination sooner by pointing higher.  A high performance keel boat can do this for one reason only, keel shape.  The deep keel is a foil that generates lift as it "pulls" through the water.  Total lift is a squared function of forward speed: double the speed, quadruple the lift.  An SJ24 keel is much more efficient upwind with its high aspect ratio and deeper keel than an SJ23.  However, the SJ23 has a keel stub so it can be easily trailer launched.

The trick to getting the most pointing performance out of the SJ23 is to drive the boat hard to maintain speed through the water, which allows the keel stub to generate more lift, which leads to less leeway.  You can aim the boat as high as you want and sheet the beejeezus out of the jib, but on the SJ23 with the stumpy keel, compounded with the flat centerboard, the underwater foil just stalls, lift goes in the toilet and the boat ends up going sideways (leeward).

I sheet my working jib to the rail, lead from about the shrouds.  For Genoa sheeting, I trim it so the leach is about a foot or more off the spreaders.  For comparison, I trim an SJ24 jib to 2 to 4" off the spreader.  The goal here is to drive the boat hard with an open slot to let the sail plan breathe, not stall the keel and minimize leeway.  In addition, the SJ23 has relatively little rocker and sailing lower and fast means you don't pound into head seas, which can stop an SJ23 dead.  When in doubt, foot off.  If you have speed through the water you have way more control options to make something happen."  Glen Moore.

You can determine the optimum sheet angle by drawing a straight line from the middle of the luff, through the clew to the deck, allowing for the height of the block.  This position is usually good for mid range winds for the particular jib.  Since you now have a "middle point" for the track you simply have to allow for about a foot fore and aft for lighter or stronger winds.  Remember to allow for the height of the block when positioning the track.  Do this for each of your jibs and you will quickly determine the position and overall length of the track.  The SJ23 manual, Tech Tip H08 (Sail Setting Guide), also has suggestions on where to place the sheet block for the optimum angle.  At one time Panache's deck track was equipped with a Merriman doublewide block, so it was possible to set a new jib sheet on the go without releasing tension on the working jib.  This is great for swapping a hanked on jib on the go.  Coincidentally, a single sheet slides easier through the double block.  If you install a single block on the track then use a spring under it to keep it standing.  This keeps it from flopping against the gel coat, which is also quieter when sailing in the "doldrums", and keeping it standing means the sheet will run easier through it. 

SIDE DECK MOUNTED TRACK (1995) - The 4' long 1" (25MM) wide track on Panache (shown at right) is through bolted to the deck.  The holes are sealed with epoxy to prevent wood rot and the track is sealed with Sikaflex.  A backing plate of tapered oak is installed on the ceiling.  It is thick enough to encase the mounting nuts thereby preventing a nasty scrape on your skull.  Wow, is that ever miserable!  There is no point in sealing the oak.  I can't remember how the track mounting nuts on Banana Split (below left) are covered but I sure wish Panache had that full 6' length to position the block precisely for each size jib. 
TRACK SPECS -
 Anodized Aluminum, 1" wide, 1/8" thick lip, 10/32" x 1.5" flat head fasteners spaced 4", stop pin hole 1/4".

The track on Banana Split, an SJ23 in Portland, was bent horizontally (along the difficult dimension) to follow the curve of the cabin.  Forming the track horizontally is best performed with a three wheel bender that has two idler rollers on one side with an opposing third middle roller on the opposite side.  As the track is drawn between the three rollers, the force (screw or hydraulic) from the middle roller bends the track in a smooth curve.  There's art involved in doing this job and it pays to have some experience.  Metal benders of this type are usually available in a specialty machine or aircraft maintenance shop.  Sometimes you can find an old guy who just happens to have one.  "This happens more often than you think.  All you have to do is ask.  Helps to have a coffee in hand." 

 

UPDATE EXTEND A TRACK (2024) - I've also seen long deck tracks consisting of two sections, one added later when the requirement changed.  But then shipping a long section of track has always been difficult and therefore expensive, so its understandable that a person would extend a track.  "It wouldn't be the first time that someone offers me free stuff and the gears start churning on how to merge this treasure in a seamless fashion.  I've been there and done that, so I don't blame you.  But at least make it look intentional and ask for a beer if someone wants to hear your story."

Design Criteria - In 2024 bought a full hoist 120% jib for which I require a longer deck track to position the sheet block further aft for the correct angle.  Conversely I need a longer track when I furl the 150% genoa and have to move the sheet block forward to the deck track.  Its a bad idea to load up a sheet block that is positioned at the end of a track.  I'm reluctant to disturb Panache's existing 4' water tight track, replacing it for a single 6' track.  So for all these reasons I will add a section of track to the aft end. 
- The 2' extension is curved to follow the cabin wall to retain deck space and for appearance. 
- The track ends are "keyed" together to prevent side movement. 
Keying is far superior to a butt joint where either track can move relative to the other.  The key only needs to be ~1/8" deep. 
- As a precaution to high track loading, the track joint
is reinforced with an aluminum backing plate against the ceiling, straddling 2 mounting bolts on either track.  The joint is shown below. 
-
To prevent marine growth the track is sealed to the deck with butyl rubber as is the slight gap between the tracks. 
- Unfortunately
the extensions arrived after launch which forced me to do the installation on the water.  So far I haven't dropped anything in the drink.  Aaarch.

Shown at right is a view of the track extension temporarily laid parallel to the cabin wall.  This view helped visualize the installation and to foresee any problems.  The foreword portion of the track extension will be bent slightly to facilitate a smooth joint.  The car slides easily across the joint without binding, a benefit of the sloppy fit that most cars have.

I made a cardboard profile of the side of the cabin which was very useful in forming the track the garage.  That is also where I cut the key in the end of the extension.  The other half of the key was cut on the deck.  Very time consuming.

Cabin Wall Consideration - I seriously thought about removing the 4' deck track to install the (4+2)' tracks as one unit on the cabin wall.  See Cabin Wall Mount below.  This would require the 4' track holes to be filled with epoxy and the deck painted with Kiwi Grip to protect the epoxy against UV.  Time consuming to do and difficult if it rains.

Upon further investigation I rejected the wall installation since the space under the window is not wide enough for the oak backing plate I have inside Panache.  I use the plate to recess the nylock nuts to prevent the installation from looking like a 1920s tractor.   If it doesn't look good it isn't sellable.  Always keep that in mind.  Ultimately, the bottom rail of the curtain is mounted below the window and I'm not about to eliminate the curtains. 

Parts:

  • 2 Anodized aluminum tracks, 1" wide, 1/8" thick lip, bevelled fastener holes spaced 4", stop pin holes 1/4".

  • 14 10/24 (5mm) x 1.5" flat head SS mounting screws.

  • 14 SS nylock nuts.

  • 14 SS flat washers.

  • 2 aluminum backing plates to reinforce the joints.

 

 

Bending Techniques: Bending the metal track to form along the cabin wall makes this installation look good and prevents stressing the fibreglass.  Bending along the short dimension is easy but along the long dimension can be difficult.  It must be done with a uniform radius matching the curve of the cabin, which is tricky.  Both tracks must be bent equally since your eye can see the parallels.  You definitely have to use your creative juices for this task.  So after bending a sample with a friend's Compact Bender there was nothing left to do but give the track a nudge.

  • Step bending track with a floor mounted Compact Bender as shown at right is the technique I used.  Its not the correct use of the tool, but if you are careful it works.  This required less effort than I thought due the leverage of the 3' handle with a built in 2' extension.  But I did position the pusher pegs close together for the most mechanical advantage.  I pushed the handle with my hip to have lots of control and to monitor the bend.  None of the anodized finish was damaged which surprised me.
    I made extensive use of the cardboard template and stopped bending as I approached the final curve, preferring caution over bravado.  As it turned out this was the correct decision with the tracks fitting perfectly along the cabin wall.

Bending can be accomplished in several other ways:

  • Rolling the track through a 3 wheel metal bender.  I thought these might be easy to find but not around here anymore.
  • Step bending the track while clamped in a bench vice might be possible.  Pull with a pipe slipped over the protruding section.  Use a long pipe for control.
  • Step bend the track between two pegs and pull it around a form.  The closer the pegs are the easier it is to bend.  You must get creative to mount two strong pegs.
  • If a twist should form in the track, use a vice and a long crescent wrench to torque the track back to flat. 
  • Failing all of this, take the track to a machine or welding shop if you don't have the skill. 
     
  • Bending the track over a sand bag is not recommended due to the lack of control.  But it does have the advantage of protecting the finish against the bag.
  • Pounding the track over an anvil risks damaging the surface and for that reason should be avoided.  It would definitely get the job done though!  Remember appearance.
     
  • Final bends being scrutinized by Merlin.  Apparently he approves.

 

 

 

Installation:

  • Drill and seal track deck holes using technique described in Tech Tip G08.
PORT STARBOARD

 

Fig 1, (left) - The masking tape facilitated outlining the track to locate the mounting holes for drilling.  Step drilling through the deck; 1/8", 1/4", 3/8" prevented tear out of the balsa core and the interior fibreglass skin.  I had very little debris in the cabin and caught all of it on a towel laid on the settee.

Fig 2, (below) - The ceiling was washed clean with acetone prior to sealing the holes with Gorilla Tape.  As a result I had no leakage from any of the 14 holes I filled.  Gorilla tape sticks very well and it doesn't leave a mark when removed.


 

Fig 3 - The G-Flex cured over a longish lunch.  The masking tape protected the surface from wet G-Flex.


 

Fig 4, (below) - The G-Flex hardened for 24 hours before scraping the surface flat with a sharp chisel. 

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Fig 5, (below) - The track was used for a template to drill the final mounting holes.  The top of each hole was bevelled for optimum sealing with butyl rubber.  After this the masking tape was finally removed and the track dry fitted.

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Fig 6 - Drill holes through track and aluminum plate.

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Fig 7 - Expand pilot holes from bottom through to back of track.  Seal expanded hole and fill with epoxy.

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Fig 8 - Port track mounted and sealed.

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Fig 9 - Starboard track mounted and sealed.

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TRACK MOUNTED ON CABIN WALL FOR SJ24 & SJ28 - Besides the potential for water leaks and wood rot in the deck core, the other problem with a deck mounted track is that the sheet block is in a perfect place to catch bare toes.  (I hate that!).  I realize you shouldn't walk barefoot on deck, but there are times when it's simply too hot to bother with shoes.  In this case, sandals are a good alternative.  Make sure they are the type that will stay on your feet to preserve your toes!

Anyway, a friend suggested I install the jib track on the side of the cabin, just below the window.  This is the factory technique on his SJ28 as shown at right.  Note that the turning block is hanging and the deck is almost clear.  Shown on the left is an SJ24 with a similar installation. 

With this technique it is possible to reinforce the track on the inside of the cabin by through bolting it to back plate or grab rail.  A shoulder height grab rail in the cabin is a very useful in rough weather or to dry clothes after the rough weather! 

The cabin wall mount is a favourite location of many designers to achieve close jib sheeting.  If I had to do it over again for Panache, I might install the track on the side of the cabin.  However, it must be backed up with a strip of aluminum inside the cabin to distribute the load which requires a lot of extra engineering.  If you want to hide the nylock nuts, cap the nylock nuts and the aluminum strip with a thin wood strip.  Get even fancier and you can install a grab rail over it all.  Makes a nice neat, functional installation that is easy on the eyes and hands. 
 

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