Saturday, September 4, 2010

A Simple Jib Lead Adjustment for Cruising Down Wind

The PDQ 32 sails at its best in light to moderately strong winds with the 130 percent genoa; the self tacking jib has serious limitations:

  • Balance. The PDQ already suffers from keels that are too far forward. Unless the main is also reefed, the PDQ likes more sail forward for balance, upwind and even more so down-wind.
  • Twist. The self tacking jib only likes one sheet setting: moderately tight. Ease it at all, and it twists of uncontrollably. For similar reasons, the self tacking jib is only furlable, not reafable.
  • Power. The boat is conservatively rigged. Until the wind hits 15 knots, more power is better, even if you're not in a hurry.
However, there are no provisions for jib lead adjustment on the genoa. Upwind she will go a bit better if the leads are brought further in, but the shrouds get in the way, unless the jib is partly furled. I have experimented with some lead locations inside the shrouds and she does point a bit higher, but it wasn't worth the fiddling and it's easy to lose any gains to leeway, if you don't sail very attentively.

Off the wind, unless the leads are moved well forward, to about the mid-ships cleat, the head of the genoa twists off miserably; in light to moderate winds this is slow and looks unsailorly. In stronger winds, the sail flogs and will stretch, and can be unstable if wing-and-wing. The answer could be long jib tracks or a barber-hauler system; both of my prior cats were race boats and were fitted with jib lead systems that could be instantly adjusted through a wide range of positions, fore and aft, and in and out. However, the PDQ is a cruising boat. The side decks are too narrow to have additional lines underfoot, the deck has a step that precludes the use of long tracks, and lifeline stanchions complicate matters.

I have been testing a simple set-up for a year now, and this last cruise gave us time for a good trial.

The parts:
  • 18-inch nylon climbing runner
  • Wire gate carabiner
  • Climbing rescue pulley. Functions like a snatch block when used with a carabiner. (CMI)
I used climbing stuff because I had it and it worked well. The runner is simply fed through and around the cleat, as a mooring line would be. The length of the runner is a compromise: too short and it will pull the sheet too close to the boat, too long and there is less adjustablity before the tack hits the block, and further forward the loads increase. It is not difficult to attach or remove in winds up to 25 knots; I've not experienced more, but in an emergency a knife would free it in seconds. Certainly a bit of rope and a snatch block would work. The length of the runner and placement of the cleat seem perfect, since when it is time to roll up some sail, the tack rises and the lead adjustment is not needed.

The first picture was taken broad reaching in 10- knot winds.Twist was well controlled and the sail was more stable.

The second picture was taken going down the Chesapeake in sustained 20-knot winds with gusts to 30 knots, and is just as stable. Although we might technically go a bit faster on a broad reach, the speeds get crazy and ride wild; we did that for a time, maintaining 12-14 knots for significant periods, but it was tiring and not much faster in terms of VMG down wind; we could maintain 8-9 knots with a ride so smooth a glass of water wouldn't spill a drop. The forward placement of the jib lead kept the genoa rock-solid with minimal twist and no oscillation. We used the spinnaker sheet, routed through a matching turning block on the other side, to rig an adjustable boom preventer. We used this rig, without touching a line, for 40 miles.

Surely, this could be a tricked out, with a turning block, a jammer, and a line led to the cockpit; I like it fine as it is. Even if the system is made more permanent, the snatch block must still be removed when not in use or it will pound on the side of the hull or deck when the sheet is slack and they can snag on the lifelines when the sheet is loaded up-wind. My parts either go below or are clipped to the lower lifeline, if they will be used again soon.

3 comments:

  1. This might also make a nice boom preventer. Run a line from the end of the boom,through the pully, back to the cockpit and cleat it off.

    Jerry

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