Trimming Sails in Tandem

The key to fast sail trim is to have both sails matched in terms of depth and trim. Here’s how to adjust your sails the leeches match and the slot stays the same.

In the Wildman and Samba Pa Ti two-boat Melges 20 program, we spent many hours on the water tuning with each other. The hulls were identical, as were masts and sails. We had marks on all of our important settings, and while tuning we talked to each on the VHF radio sharing our settings. Yet, we often went different speeds, even when those settings were identical. Granted, hiking and steering were variables, but it became really apparent how important it was to make sure the jib and main were matching each other with simple adjustments of the sheets.

A coach watching from behind in a powerboat can easily see if the sails are well-matched. If a team’s sail plan looks out of whack from behind, you can be sure they’re going slow. Typically, on slow boats, one sail will be much looser or tighter than the other. Or it might be flatter or fuller than the other. Fast boats have similar depth in the main and jib as well as similar twist profiles.

Even if conditions don’t dictate flat sails, flat sails trimmed well and together will still be faster than mismatched sails. Matching your sails keeps the slot a similar distance apart from top to bottom. Our coach, James Lyne, continually reinforced this fundamental. For example, he would say, “Ease your jib a quarter inch and trim in the main half an inch.” And after these small changes, voila! Off we went, which hammered home the importance of not only trimming the sails very precisely but also having the leeches match and then trimming them together when we make changes. To do that, you have must have really good communication.

Sail-Trim Matching
On the Melges 20 Samba Pa Ti, note how the leeches are matched and the slot between the sails remains open. James Lyne

I’ve found the best way to match your sails is to talk in terms of power, and the main trimmer or the helmsman usually make that call. On the Melges 20, I communicate power to the jib trimmer, Erik Shampain. For example, I say, “Perfect power.” That lets him know I am trimmed in to the sweet spot, heel angle is good and everything feels right. Then, if a lull comes and I have to trim harder to get more power, I say, “Two-blocked, just OK.”

If the wind lightens more, I say, “Searching for power.” This means it’s time to adjust controls—outhaul off, and more inhaul on the jib to create more depth and power in both sails. At the same time, our other crew, Stephanie Roble, adjusts the vang and cunningham to further increase power by making the main fuller.

On the flip side, if we have perfect power and the breeze builds, I say, “Easing main, overpowered.” Erik reduces inhaul, flattening the jib, and Stephanie adds vang and cunningham to flatten the main. The result is that both sails are flattened slightly, and I can trim back in a little, keeping the main closer to centerline. As the breeze comes up, we flatten the main even more, move the jib leads back and stop inhauling. We are always talking about power, which tells us what to do with the controls to match the sails.


Helm load information is another way to talk about coordinating sail trim. If the boat is heeling too much and the driver is feeling too much helm, they should mention it to the main trimmer so they can depower the main, which reduces heel angle and reduces helm. If the main trimmer needs help from the jib trimmer, for example the backstay is already tight and the traveler is down, that information gets passed forward.

On boats such as Etchells and J/70s, adding backstay tension tightens the forestay, which in turn affects the jib shape. Communicating what’s happening with the backstay and traveller queues the jib trimmer to adjust the jib to match the new mainsail twist profile. Small changes to the backstay and traveller need not be communicated but big changes warrant adjustments of both the main and jib sheets.

As a high school sailing coach, one of my best crews ever is Rebecca McElvain. She won four high school national championships while at Point Loma. She always watched her skipper’s main trim to match her jib trim. When he eased, she eased. When he trimmed in, she trimmed in. This simple style of trimming together is really fast. Now sailing for Dartmouth, her skipper queues off of her to coordinate the trimming. As the breeze comes up, she hikes harder and trims in a few clicks. Her skipper matches that. Conversely, when the wind drops, she slides in and eases a small amount. Playing off of her body movement, the skipper does the same, knowing it coincides with jib trim. It doesn’t make any difference which person makes the call. As long as the sails are adjusted together, you’ll be faster.


One place on the upwind leg where it’s really important for the two trimmers to keep the sails matched is when coming out of a tack. Typically, coming out of the tack, both sails are eased to about 80 to 90 percent of full trim. As the boat gets up to speed, the main trimmer says, “Almost at speed” and then “Trimming to final.” This communication allows the jib trimmer to match jib trim. A big mistake when coming out of a tack and building speed is to have the jib at max trim and the main eased. This closes the slot, and your speed build will take three times as long.

A simple way to trim together is to announce when you’re trimming or easing. When steep chop is approaching and I know the skipper will put the bow down to accelerate through, I say, “Easing in three, two, one, easing.” This lets the jib trimmer know when to match me. Once through the chop and the skipper starts to head back up, I say, “Trimming.”

In very light winds, the jib trimmer is often sitting to leeward, actively trimming the jib. In this scenario they should lead the calls and announce their small changes so the main trimmer can match. For example, if a lift hits the boat, rather than the skipper jamming the tiller over to head up, the jib trimmer will ease the jib so the forward tell tales stream. They say, “easing to you,” meaning that they’re easing to the new wind direction. The main trimmer can then match the jib with a small ease. The boat will accelerate nicely with both sails eased and the boat’s angle slightly below close-hauled. As the skipper smoothly heads up, the jib trimmer says, “Trimming in.” The main trimmer should match, and off you go.


Lastly, in big breeze when the main is eased to where it’s on the edge of luffing, it’s important for the main trimmer to ask the jib trimmer for eases in big puffs rather than luffing the main. If your boat is set up correctly, your jib should be trimmed firmly enough so that only in the massive puffs does the main get eased far enough to start luffing. In those moments, if the jib trimmer eases the sheet simultaneously, the boat will stay on its feet, and the main won’t flog. Once the big puff dissipates, both trimmers bring the sails back in to perfect trim.