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Tweaked For Jib-Shape Perfection

To improve jib-trim adjustments on their vintage Moore 24s, two pro sailors took different paths toward the same goal.

October 30, 2013
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Tweaked for jib-shape perfection

Tweaked for jib-shape perfection

Douglas Hull

As the first production-built ultralight displacement boat, the Moore 24 enjoyed a build run until 1988. Of the 156 built, 151 are still afloat today. With its deep Santa Cruz roots, the Moore 24 has become a cult classic among West Coast sailors, especially a cadre of pro sailors including Steve Bourdow, the Flying Dutchman Olympic silver medalist, and Mark Christensen, a world champion in the Melges 24 class and three-time winner of the Volvo Ocean Race. These guys can’t help but take their Moore 24 racing seriously, and in preparation for the class’s national championship in June, a few of them went to work on significant jib-lead modifications.

“Sailing in Santa Cruz can be tricky, with a lighter breeze near the shore that can often build by 10 knots as you proceed up the course,” says Christensen. “The wind is very puffy, and the headsail you choose to get off the starting line with is often the wrong sail by the time you reach the top mark. We needed a system that offered more flexibility, one that would allow us to use the right sail at the start and also allow us to depower and carry the sail beyond its range as we get to the top mark.”

Christensen sails on Pegasus Motion X, a 1983 Moore 24 that’s constantly upgraded. It’s one in a fleet named Pegasus and owned by Philippe Kahn, the serial entrepreneur and performance-sailing zealot. Jib-lead modifications on Pegasus Motion X would allow tighter sheeting angles and better shape control.

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Christensen and his teammates removed the boat’s original longitudinal (fore and aft) genoa tracks and replaced them with three athwartships transverse tracks, a unique configuration for boats with overlapping genoas. What they hoped to achieve was a wider range of jib settings that would allow them to close the sheeting angle at will, change the sail’s draft, and retain power with more breeze.

A key element of this modification was positioning the tracks. Get it wrong, and trimming wouldn’t work. To determine the location, they simulated the forward-most longitudinal track setting for each headsail (they carry No. 1, No. 2, and No. 3 jibs) by sheeting each sail at the dock, pulling down a line immediately below the clew at the farthest point forward the track would go, and marking the spot on the deck with tape. They then went around the course where they regularly sail to confirm the tape marks corresponded to the best position on each leg.

Once they were confident with the clew positions, they fastened their tracks from the outer edge of the deck. Each track had its own car. They also had rings welded onto every car so they could tie a block to each one and run a line up to the clew. The line attaches a purchase system that runs under the deck beneath the cabin top, across to the opposite side, and out to a clamcleat. The setup gives the jib trimmer as much as a six inches of vertical adjustment. The entire system ultimately gives the trimmer more flexibility to shape the jibs and allow the boat to point higher or depower as the wind builds.

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Bourdow saw Pegasus‘ setup and liked it. The former head coach of Stanford’s sailing team has easy access to Christensen, who lives next door in Santa Cruz.

“We have plenty of time to chat even though we hardly ever tune or practice,” says Bourdow. “I noticed new gear showing up on Pegasus and found Mark’s configuration appealing.”

However, the customization of Pegasus‘ system has its drawbacks. The setup is hardware intensive: clew-height adjustment requires six individual purchase systems (one set per track), and tuning each car individually proved too complex. The workaround was to send a crewmember below to unhook and refasten the end of the gross to a preset loop matching the correct jib during a sail change.

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Bourdow replicated the placement of tracks found on Pegasus, but used shorter tracks, saving money on hardware. His No. 3 track is 22 inches long, anticipating a need for a wider range in stronger winds, while the No. 1 and No. 2 jib tracks are only 12 inches. He positioned the tracks closer to the centerline of the boat, starting 9 inches from the rail, knowing Christensen only used the outboard settings for occasional reach legs or long distance races. He didn’t see a need for extreme outboard settings.

Installing the tracks was a simple matter of drilling holes, fabricating a backing plate from 1/8-inch G10, and applying silicone sealant before screwing the bolts. It was a two-person job, requiring one person on deck holding the bolt in place while the other tightened the nut from below.

Designing and installing the purchase system for the clew-height adjuster was more involved. Bourdow wanted a simpler system than that found on Pegasus. Moorgasm, the 1979 boat he co-owns with Dave Josselyn, had recently undergone a major hull refit. Keeping modifications within budget mattered, so Bourdow chose to minimize the number of parts. His system differs from Christensen’s in three ways: 1. He configured the lines to cross under the cockpit, exit through the cockpit floor, and lead to a pedestal he built himself. 2. He chose to use one adjustable car per side, rather than drill more holes, and use dedicated cars for each track. 3. He positioned the under-deck purchase so as to require the fewest possible turning blocks, as well as fewer holes drilled through the boat’s bulkheads.

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Rather than drill new holes through the deck, Bourdow used existing hardware to fasten the blocks, directing the purchase system under deck, to a deck-joint bolt, or a deck fitting, and trimmed a couple of aft bolts to avoid them getting in the way of the purchase system. His vertical-lead adjustment controls terminate in trapeze cleats on the cockpit pedestal that also holds the mainsheet and backstay.

Bourdow figures his configuration cost no more than $300 in parts. He suggests using inexpensive string to temporarily rig any system in order to figure out how much line to purchase before proceeding to final installation.

The Pegasus team starts with the cars almost all the way inboard and moves them progressively outboard as the wind increases, within a rough six-inch range, unless on a reach.

The clew-height adjustment is used for quick changes in velocity. Bourdow and Christensen use it to depower during extreme puffs, allowing the clew to rise and the leech to twist off, or to pull the clew down in light air to straighten the leech. Otherwise, they keep the vertical adjustment fixed once they’re happy with the general setting.

Depowering this way, says Christensen, is the same as pulling the jib car aft: “It twists the jib and spills power so the main won’t blow out,” he says. “But now we can use our No. 2 when everybody else is using their No. 3.”

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