sailing yacht

How to Do a Late-Main Jibe

The late-main asymmetric spinnaker jibe is an essential technique, especially in light air. The steps to a successful jibe are straightforward. The ­spinnaker trimmer eases the clew to the headstay while taking up slack on the weather sheet. Once the clew is around and at the shrouds, the main trimmer can start pulling the mainsail across. The spinnaker should be full and pulling before the main fills on the new jibe. (Andy Horton/)

The problem with conventional jibes, where the main and spinnaker cross the boat simultaneously, is that the mainsail acts like a big wall, pushing air the wrong way across the spinnaker. That makes it harder to fill the spinnaker on the new jibe. And the longer it takes to fill, the longer you’ll be sailing slowly.

Picture this: You’re about to execute a conventional jibe, from starboard to port. The wind is flowing from right to left across the spinnaker—from luff to leech. Jibe to port and the wind now flows from left to right, still from luff to leech.

Now let’s consider the mainsail. While on starboard jibe, the wind flows across the main from right to left—again, from luff to leech. But as you jibe, the main starts pushing air ahead of it as it crosses the boat. That pushed air hits the spinnaker, which is also trying to fill at that moment, from luff to leech—in this case, from left to right. That means that, until you settle onto the new jibe, the flow moving across the spinnaker is countered by the flow created by the main. The net result? It becomes much harder to fill the spinnaker—no flow, no drive—meaning the sail is not working at its potential through the jibe.

Enter the late-main jibe. As its name suggests, you jibe the spinnaker first, then the main. Done right, the spinnaker is not affected by the main and can keep you on a faster track downwind.

Here’s how it’s done. As the boat bears away into the jibe, ease the active sheet so the spinnaker is just curling. Typically, that ease is a little ahead of the turn. Keep the sheet tensioned until the clew of the spinnaker is at the forestay. Simultaneously trim the new sheet. For a few seconds, the new sheet will be pulling slightly against the old sheet. The idea is to create a direct load transfer from the old sheet to the new, so don’t just let the old sheet go before the clew reaches the headstay. Do that and the spinnaker will go out in front of the boat, luff, and you’ll lose speed.

Rapidly trim the new sheet until the clew reaches the new leeward shroud. At that point, the boat should be pointing just by the lee, and the spinnaker should start filling. You might even end up wing-on-wing for a second. The helm watches the spinnaker clew, and once the spinnaker starts to fill, they will typically say, “Finish it off!” That is the cue to jibe the main.

The key is to initiate the flow across the spinnaker and get the spinnaker full and pulling before jibing the main. Done right, the main should almost float from one side to the other. Jibing the main a little late is always better than letting it cross too early. If you let the main hit the other side before the spinnaker fills, you’ll end up back in conventional jibing territory. It’s even OK if you’re wing-on-wing for a few moments.

Still doing conventional asymmetrical spinnaker jibes? There’s a faster and much 
more efficient method.

Still doing conventional asymmetrical spinnaker jibes? There’s a faster and much
more efficient method. (Andy Horton/)

In light air, your boom is probably not going to be all the way out because you’re reaching a little. When you turn down into the jibe, ease the main. That not only aligns the main with the new wind angle, but also allows you to bear off farther yet before the main wants to cross the boat. If you end up sailing by the lee, or the main wants to cross the boat early, have someone hold the boom out, especially if it’s bumpy. As a general rule, if the main wants to cross too early, try easing the mainsheet more before the turn down to jibe.

As the breeze increases to around 12 knots, a late-main jibe is easy because the apparent wind drops as you bear off into the jibe, reducing pressure on the main. Now when you bring the main across, the boom should land gently on the new leeward side. It’s not pushing any air, and throughout the jibe, the spinnaker is pulling you dead downwind, at speed, toward the mark.

At 15 knots, you’ll be sailing deeper, so the boom is going to be pretty far out when the jibe is initiated. If the main comes crashing across, bring the boom in a little as you go into the jibe. At 16 to 17 knots, when you turn down, trim the main instead of easing it. If the boom is over the leeward corner of the boat and the driver turns down to where you’re almost by the lee, the wind on the leeward side of the boom will help it across. In stronger winds, tail the mainsheet 100 percent of the time when bringing it across. When it lands on the new side, be sure to ease it immediately to avoid shock-loading the boom and mainsheet tackle.

RELATED: How to Use Jib Telltales

The top windspeed for a late-main jibe depends on your boat. If you have running backstays, when it gets windy, you’ll probably need to do what’s called a “priority main jibe.” That’s where the first goal is to get the main across. Above 20 knots, you might not be able to pull the main across, and sailing wing-on-wing might be really difficult, so there’s an upper limit, but it can be pretty high. If you lose control coming out of the jibe, you’re over the limit.

For the helm, a late-main jibe is great because it’s a slow jibe. It gives you more time to find the correct exit angle, and there are clear indicators of how the turn is going. Turn down until you’re by the lee, keep the boom out, see the spinnaker fill on the new side, and then say, “Jibe the main.” The landing is pretty easy because the full spinnaker helps keep the bow down, and the main just kind of flops across. ν

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