The jib lead is the block or fairlead through which the jib sheet passes between the clew and the winch, and its position controls the direction in which the sheet pulls the clew. That direction decides how the sheet load is divided between the leech and the foot, and so controls the twist and depth of the entire headsail. The beginner needs to know that moving the lead aft opens the leech and moving it forward closes it. The experienced trimmer knows that the lead has two axes – fore and aft on the track, and inboard or outboard by inhauler or barber hauler – and that finding the right lead is the first job in setting up a jib, before halyard or sheet are touched.
How the Jib Lead Works
Imagine the sheet extended from the winch through the lead and on up through the clew into the sail. Where that line meets the luff tells you how the sail is loaded. If the extended sheet bisects the clew angle, roughly hitting the luff at about 40 per cent of the way up, the leech and foot are tensioned in balance and the sail sets as the designer drew it. Move the lead aft and the sheet pulls more along the foot: the foot flattens, the leech eases and twists open, the top of the sail spills wind. Move the lead forward and the sheet pulls more downward: the leech tightens, twist disappears, and the foot rounds up as it is no longer being stretched.
Finding the Right Lead
The classic test uses the luff telltales. Sail close-hauled with the sheet trimmed, then luff slowly. If the top windward telltales lift before the lower ones, the top of the sail is too twisted and the lead is too far aft; move it forward. If the bottom ones lift first, the leech is too tight and the lead is too far forward; move it aft. When all the telltales break together, the lead is right for that sail in that breeze. Then check the leech: the top leech telltale should stream most of the time, stalling only occasionally, and the foot should be a smooth curve without a hard fold along the deck.
Why It Matters to the Sailmaker
Every headsail leaves the loft with a designed clew height and sheeting position. Get the lead wrong and the sail is being asked to hold a shape it was not built for: a lead too far forward on a laminate jib loads the leech far above design and encourages the cloth to stretch or the leech to cup, while a lead too far aft can flog the top of the sail and kill it early. UK Sailmakers’ load-path sails such as Titanium and X-Drive have fibres laid along the clew-to-head and clew-to-tack load lines, which is exactly the geometry the lead controls, so the sail rewards a lead that matches the design and punishes one that does not. When you order a sail, tell the sailmaker where your track runs and where its end stops are; a clew designed to lead within your track saves a season of frustration.
Cruising and Racing Perspectives
On a cruising boat the lead is often left in one place for years, which costs pointing and comfort. Two adjustments pay for themselves: moving the lead forward when the jib is partly furled, which stops the leech from flogging and beating the sail to death, and moving it aft in a fresh breeze so the top spills and the boat stands up. Adjustable leads with a control line back to the cockpit make this easy without going forward; if you only have pin-stop cars, mark the track with tape for full sail, first reef and second reef positions.
Racers treat the lead as a live control. Fore-and-aft cars adjusted under load, inhaulers to pull the clew inboard for pointing in flat water, and barber haulers or outboard leads for reaching are standard. A trimmer will change lead position several times on a single beat as the breeze and sea state change, and will note positions for each jib on the track so the setup is repeatable. Under class rules the track may be restricted, which is why floating leads and inhaulers have become so common.
Frequently Asked Questions about the Jib Lead
Which way do I move the jib lead to depower?
Aft. That eases the leech, lets the top twist open and flattens the foot, so the sail generates less heeling force without your having to ease the sheet and lose pointing.
Why does my furled jib flog at the leech?
Because rolling the sail raises the clew and moves it forward, and the lead is now too far aft for the new clew position. Move the lead forward until the leech settles.
The jib lead is the least glamorous control on the boat and one of the most powerful. Set it before you set anything else, move it as the wind and the sail change, and the headsail will give you the shape your sailmaker built into it.