Ask Sail: How Far to Ease Out?

Author:
Publish date:
It’s all about projecting more sail area dead downwind

It’s all about projecting more sail area dead downwind

Q: When sailing dead downwind (assume 22 knots of wind), if the main is eased out to 90 degrees relative to the wind (perpendicular to the wind) are roughly the same forces applied to the sail as to the sail if it isn’t quite out all the way, say, 75 degrees to the wind? My spreaders don’t allow me to let the main out all the way on a run, because they are swept. My friends said a 32-footer with a nearly identical sail plan and sail configuration walked right by us because my main couldn’t ease out to 90 degrees and his did. I disagree. I have a 140-percent genoa, and he had (maybe) a 150 percent headsail. Both were wing-and-wing. The only other difference was that his genoa was held open by a spin pole, mine wasn’t.

— Dana Paulson, Washington, DC

BRIAN HANCOCK REPLIES

If indeed, you are sailing dead downwind, in other words the wind direction is perpendicular to the transom of your boat, I’m afraid you are wrong. At that point of sail, it’s all about projected area, and the more area you can project, the better off you will be. Try this experiment. Sail dead downwind with your mainsail all the way out plastered up against the spreaders. Record your boatspeed. Now sheet it in so that it’s around 45 degrees and record your boatspeed. Now bring it onto the centerline and see what happens. Each degree of reduced projected sail area will reduce your boatspeed.

Note, this applies only to sailing dead downwind. As soon as you harden up onto a reach (or a beat) things change. When you are sailing dead downwind the wind is sucked around the edges of the sail and under the boom to the leeward side. However, as soon as you harden up, the wind starts to flow across your sail, in the process attaching not only to the windward side but the leeward side as well, thereby producing lift. As you start moving across the wind, you will also begin creating apparent wind, which will cause you to go faster still. With this in mind, with your swept-back spreaders you might want to consider heating the angle up a little, say, to a broad reach, which will increase your boatspeed sufficiently to more than compensate for the extra distance sailed. With any luck, when you gybe back in toward your original rhumb-line course, you’ll end up well ahead of where you would have been if you’d sailed the shorter, more direct heading.

One other thing: it’s possible that by flying their genoa on a spinnaker pole your “competition” was able to project more headsail area as well, which also contributed to them having some extra boatspeed.

Got a question for our experts? Send it to sailmail@sailmagazine.com

Related

Shelly-forward-last-day

Charter Advice for First-Timers

Never chartered? No worries. A vacation under sail can be the most memorable time of your life. That said, it also pays to be prepared by doing some reading, building your skills and listening to what the experts say. First and foremost, not all charter grounds are created ...read more

HugoBoss

Video: Vendeé Update

Last week Alex Thomson (Hugo Boss) led the fleet across the equator. As one of the class' top sailors who's been on the Vendeé Podium twice, it seemed possible that Thomson was going to grab an early lead and hold on to it all the way around the world. But early on Saturday, he ...read more

AdobeStock_229409051

Chartering Again for the First Time

It’s been a rocky road of late for the charter industry, especially here in the Western Hemisphere. First came hurricanes Irma and Maria in the Caribbean followed by Dorian in the Bahamas. There has also, of course, been the coronavirus, which burst into global prominence ...read more

01 LEAD cedaryachtclub_onedesign18_hike

An Interview with Ayme Sinclair

In recent months, US Sailing, like many organizations, has been taking a closer look at diversity to ensure it’s doing the best job it can of introducing people from all backgrounds and ethnicities to the sport. As part of this effort, this past summer it organized an online ...read more

125768940_10222759720523627_5373654001582879638_n

US Sailing Presents Adaptive Sailing Panel

On Tuesday, November 24, US Sailing’s Leadership Forum will present the latest panel discussion in their Diversity, Equity and Inclusion series. This event will focus on adaptive sailing and provide practical recommendations for organizations looking to expand their adaptive ...read more

02-IMG_5971

A Carbon Neutral Circumnav with Jimmy Cornell

Historic anniversaries have always held a special fascination for me, especially if they mark a significant nautical achievement. In 1992, on the 500th anniversary of Columbus’ would-be voyage to India, I organized a transatlantic rally that followed the historic route of the ...read more

DJI_0068

SAIL Podcast: Jimmy Cornell’s Carbon-free Circumnav

In this episode of Point of SAIL, Principal Editor Adam Cort talks with bestselling author and pioneering bluewater sailor Jimmy Cornell, who set out November 19 on yet another circumnavigation aboard a newly designed, carbon-neutral Outremer 4Zero catamaran. The voyage, which ...read more

emirates-600x

Emirates Team New Zealand Splashes the last of the AC75s

Emirates Team New Zealand unveiled its second-generation AC75 yesterday, joining the other three America's Cup teams with boats in the water. In just over 100 days, this boat will attempt to defend the Cup for the Kiwis, but there's plenty of racing between now and then, with ...read more