Tech Team - Self-Tacking Jibs

The Crossbow™ self-tacking jib system is designed for high-performance dinghies, skiffs, and catamarans under six meters (20 feet). The system features a curved track that hinges to align both car and track with the sheet loads for less friction, more load-bearing capacity, and for an ultra-lightweight design.

Self-Tacking Jib Systems

12/8/2014

Self-tacking jib image_230 Self-tacking jibs are increasingly popular on new-build yachts. They make a boat very easy to sail upwind, with minimal effort and action required!

There is a trend to fit self-tacking jibs onto older boats. This is easily done, but requires some thought.

Basically, the sheet from the jib is led to a car which moves across the boat when the boat tacks-very much like a mainsheet traveler.

Tracks vary from straight across the boat, to bent track with the ends forward, to bent track ends-up and then tilted forward. In each case, the idea is to make the car movement smoother and the sheet tension more consistent. It can be a challenge to work out the ideal bend. For help, contact your sailmaker, or give Dr. Harken a ring!

There are three basic ways to rig the sheet:

  1. Transverse sheet
    This technique is a straightforward, but can be expensive. Transverse sheeting also has the potential for producing more friction as the boat tacks because all the blocks in the sheet system roll along the sheet. There are occasions when transverse sheeting is the best system, but other options are worth considering.
  2. Sheet forward
    In this system, the sheet stays under relatively constant tension and does not move through the blocks when the boat tacks. To do this, the block or through-deck block needs to be as near the jib tack as possible. Your challenge is returning the sheet all the way back to the cockpit. This can be difficult, and might result in significant friction.
  3. Sheet up the mast
    This is an increasingly popular approach, and it is easy to see why. The sheet goes up the mast far enough to ensure correct tension through the tack. It returns to the deck (either internally or externally), and then back to the cockpit with the rest of the mastbase lines. The sheet doesn't move through the blocks in the tack, so friction is minimal.

Watch out for:

When jibing downwind, the car travels along the track very quickly, colliding hard into the endstop, This can damage the car, endstop, or both. To avoid this, either furl the jib before jibing, or apply a leash to prevent the car from smashing into the end of the track.

When sailing off the wind, a different, larger, or more shaped sail is often used, with the ST jib furled away. The ultimate expression of this approach is the so called "Slutter Rig", with a reaching sail on a furler located just forward of the self-tacking jib furler.

If you decide to go with straight track, the sheet and/or jib foot will go slack in the middle of the tack with the tension coming on as the car reaches the end of the track. This can be a useful feature, but if the sheet is too tight, the car never reaches the end of the track which is not ideal.

Using pinstops to limit travel are often considered desirable, but should be unnecessary if the track ends are in the right place.

For more information on self-tacking jib systems and how they can be useful on your boat, please feel free to contact Harken for more information.

Harken self-tacking jib systems include:

CodeSize
2758.1.1M.2020 mm
2758.1.1M.5050 mm
2758.950MM.20950 mm
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