Jack-stay Installation Advice

Material selection is just one of many details regarding jackstays that deserve careful thought.

Although you can use existing hardware for anchoring jackstays to your deck, finding adequate anchor points on light boats can be difficult, since the deck and fittings might not be very strong. Whatever hardware you use must be strongly reinforced and capable of supporting the anticipated loads.

Confirm that the entire system is of known minimum strength. The International Sailing Federation (ISAF) standards recommend 4,500 pounds (2041 kg) minimum breaking strength for webbing, although we recommend more for boats longer than 40 feet in order to provide an adequate safety factor. The minimum safety factor is 2.4:1, based on dynamic loads. This means that the gear you use should be capable of supporting 2.4 times the amount of force generated by a falling body (or bodies), or by a person who is dragging in the water at maximum boat speed.

Nylon webbing stretches a great deal when it is wet, so nylon jackstays should be tensioned when wet.

Webbing jackstays should be twisted—not laid flat. This makes them easier to clip into when wet, and they won’t flap in the wind.

Outboard-powered boats should never have jackstays or tethers so long that a sailor who has fallen overboard would be towed behind the boat near the prop.

Jackstays should stop well short of the bow. Fast boats, multihulls in particular, can hurl a person forward when the bow stuffs into a wave.

The cockpit should have at least one dedicated fixed point for clipping into. Consider installing dedicated clip-in points (padeyes) at other work stations—i.e. at the mast or at the bow.

Rope jackstays can be acceptable on boats with higher coachroofs that allow the lines to be routed off the deck where they won’t fall underfoot. Rope is more durable than most other choices; it is also easier to clip on and off with carabiners.

When Dyneema or stainless cable are used on the deck, sheathing them in tubular webbing can reduce their rolling under foot. However, some of our testers preferred exposed Dyneema because the clipped-on carabineers slid along the jackstay more easily.

Jackstays must be clearly distinguishable from running rigging, so that there is no chance of clipping into the wrong line. Colour is not enough, as the typical deck is littered with control lines, and colours are indistinguishable in the dark.

Jackstays should be permanently rigged during a passage. It takes time to become accustomed to their use, and sailors have often gone overboard in benign conditions.

Jackstays should be rigged under sheets and over deck-routed control lines so that a sudden tack or jibe does not grab the tether.

If you rely on stainless-steel hardware, use only the highest quality.