Skip to main content

Judging Leeway

Any boat under way in a crosswind, whether it’s a rowboat crossing a lake or a powerful cruiser reaching along the coast, will be pushed sideways to some extent. The effect is called “leeway,” and even big ships are subject to it. Sometimes leeway is insignificant; often it is not.

Any boat under way in a crosswind, whether it’s a rowboat crossing a lake or a powerful cruiser reaching along the coast, will be pushed sideways to some extent. The effect is called “leeway,” and even big ships are subject to it. Sometimes leeway is insignificant; often it is not. If you don’t account for it when plotting a course, grief may be your reward.

If you can see your destination, you can check whether you’re being blown to leeward by lining up some fixed object near where you’re going with an object behind it. This effectively creates a range that works the same as those thoughtfully set up by the authorities to lead ships into harbor.

If there’s no significant current and your two range objects “open,” or move relative to each other, you are making leeway from your direct line. The solution is to steer “up” into the crosswind to close your markers and keep them lined up.

You can see that the boat in the illustrations has to head up about 10 degrees in order to stay on the line. If she steers straight for her destination she drifts off course, the range opens, and she must steer firmly upwind to close it again.

When your destination is invisible because of thick weather or distance, you’ll have to plot a course. Estimating leeway is a part of the process. A small yacht close-hauled in a stiff breeze may slide to leeward by up to 10 degrees. As she bears away her leeway will diminish steadily as the wind draws further aft until, when running, there’s none at all.

COMPENSATING FOR LEEWAY

It’s easy to get confused when numerically figuring leeway into a course-to-steer, so it pays to do the job graphically. Sketch a wind arrow somewhere on your chart, place your chart protractor on the course you want to sail, imagine your boat is sailing up the edge of the protractor and see which way to turn it to counteract her tendency to be blown downwind. Swivel it between 5 and 10 degrees toward the wind and read off the heading you’ll actually steer.

APPLYING LEEWAY

If you’ve already been steering a course and have not compensated for leeway, when the time comes to estimate your position you’ll need to know where on earth you are really tracking. The answer is to apply the same technique retrospectively. Sketch the wind arrow on the chart and lay your protractor on the course steered. Now swing it 10 degrees or so away from the wind, redraw the course and you’ve cracked the problem. 

Top Illustration (by Steve Sanford): Sailing on a beam reach, the boat above first falls to leeward, “opening” a pair of range marks on shore (left); the boat steers a high course to close them up again, but overcompensates, so that they are once again out of line (center); back on course, the marks line up correctly (center)

Related

m138123_14_00_210609_TORE02_SE_2152_2504-2048x

The Ocean Race to be “Climate Positive”

The 2023 Ocean Race intends to be one of the world’s first climate positive sporting events, offsetting more greenhouse gasses than are produced. The two-fold effort means cutting emissions by 75 percent and investing in ocean projects that sequester carbon and restore ocean ...read more

01-LEAD-Ancients-3-2048x

Cruising Lake Superior

Almost anywhere a sailor drops the hook someone else has been there before. We are hardly ever the first. That remote Maine harbor without a soul in sight: there’s a lobster trap. The south coast of Newfoundland: the crumbling remains of a fisherman’s cabin lie hidden among the ...read more

01-LEAD-Tablet-Holder-4

Fabricating a Tablet Holder

During the pandemic, I was stuck aboard Guiding Light, a Lagoon 410, in St. Lucia for over a month. During that time, as I worked on the boat, I started by doing a spring cleaning in my spares locker and finding some parts and material that I forgot I had. As soon as I saw them, ...read more

00-LEAD-AdobeStock_486335954

A Catamaran for a New Era

Anacortes, Washington, is an unassuming sea-salty town near the San Juan Islands of Puget Sound, and the Betts Boats yard is easy for a passerby to miss. But within Betts’ facilities, the dawn of an era in Pacific Northwest production boatbuilding could be breaking with the ...read more

X5_plus_slide-01

Boat Review: Xquisite X5 Plus

The Xquisite X5 Plus is a major update of the boat that SAIL awarded Best Large Multihull and Best Systems titles in 2017. The changes were not just cosmetic, but genuine improvements to an already fine boat, making it lighter, faster and less dependent on fuel. The builder’s ...read more

01-LEAD-AdobeStock_40632434

Cruising: Offshore Prep Talk

When I began preparing Minx, my 1987 Pearson 39-2, for extended Caribbean cruising, I had to balance my champagne wish list against my beer budget. Every buck spent on the boat before leaving would be one less frosty can of Carib down in the islands. On the other hand, I had to ...read more

m5702_RACE-AREA-6

Barcelona Venue Shaping Up

The decision to host the next America’s Cup in Barcelona ruffled the feathers of some fans, but the Defender is happy with how the venue is shaping up. The process of allocating team bases, spectator zones and the race village is underway. “I cannot speak highly enough of the ...read more

ELAN-GT6---273

Boat Review: Elan GT6

Elan’s first sporty “Grand Turismo” yacht, the 43ft GT5, launched in 2017, and was actually a bit of a mash-up. It combined an existing go-fast hull from Elan’s sexy E5 racer with a new deck and interior optimized for cruising comfort, and a somewhat detuned rig to create a ...read more