Ask SAIL: Powering Up a Main

Author:
Updated:
Original:

Q: My friends tell me that I need to “power up” my mainsail in light winds, but I am not really sure what that means. Can you explain? I race a Pearson 37, mostly beer-can races.

Joseph O’Brian, sailmail@sailmagazine.com

BRIAN HANCOCK REPLIES

Powering up your main is very important in light winds. Equally important is being able to “depower” the sail when the wind comes up. Powering up your main means adding depth to the sail. Mainsails are designed with a specific chord depth (draft, or curvature depth) for general sailing purposes. In light winds you want to increase the chord depth, and there are a number of ways you can accomplish this. The first and easiest thing you should do is ease the outhaul. This immediately adds depth to the sail because you are effectively bringing the leech closer to the luff. Also, ease the halyard or cunningham. This, in turn, relaxes the fabric along the luff allowing the draft to increase. Another important thing you can do is to ease the backstay, effectively straightening the mast. The reason for this is that part of the sail’s overall shape is induced by the amount of luff curve the sail designer has specified for the sail. When the mast is bent, the luff curve matches the mast and the sail has a flatter shape. When the mast is straightened (by loosening the backstay) that luff curve shape is pushed into the body of the sail and increases overall depth. To depower a sail, simply do the reverse to reduce the amount of draft, or curvature, thereby producing a flatter sail.

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

April 2017

Related

09-Map-Route-VG2020

Vendee Globe Village Closing, Race Still On

Following the latest national lockdown measures announced by French President Emmanuel Macron as part of the fight against Covid-19, the 2020-21 Vendée Globe Race Village will be closed to the public beginning Friday, October 30th. The Vendée Globe will still take place as ...read more

Register-2048

Register of Circumnavigators Launched

Just in time for a fresh class of Vendée Globe sailors to attempt their circumnavigations, The International Association of Cape Horners (IACH) has taken on the responsibility of maintaining an official register of sailors who have completed solo circumnavigations by the Three ...read more

FPO skys0tlm8jlrpynehcpe_NEW

A Half-century of Cruising with SAIL

I cannot say I have been reading SAIL magazine since the very beginning, but I come pretty darned close. Sometime around 1974, when I was in high school, I began buying it every month at our local newsstand and saving every issue until I had great stacks of them, as carefully ...read more

B&G-Halo20+-side-facing

Gear: B&G HALO radar

B&G’s HALO series of radars now includes the HALO20+ and the HALO20, a pair of compact radomes expressly designed for use aboard smaller sailboats. The units measure 20in in diameter and weigh a mere 11lb. The HALO20+, in particular, delivers a full 360-degree sweep every ...read more

PICTON CASTLE under sail with stunsls WV7 compressed

Picton Castle Seeks Crew

The Picton Castle is set to begin its eighth circumnavigation this spring under the command of Captain Daniel Moreland. A professional crew of 12 will guide up to 40 trainees at a time as they learn about all aspects of sailing the bark, from steering to lookout, ...read more

DSC_0013

Ask Sail: Keel Attachments

Q: I have an early ‘70s Catalina 27. The keel bolts look pretty good. My question is, why not glass over the keel to bond to the hull rather than changing the bolts if, or when the bolts are too far gone? I haven’t seen anything on this, so could you discuss? Full-keels are ...read more

04-GOPR0511

Book Review: Sailing Into Oblivion

Sailing Into Oblivion by Jerome Rand $15.99, available through Amazon As refreshing and inspiring as Jerome Rand’s 2017-18 solo-circumnavigation may have been, his account of the voyage in the book Sailing Into Oblivion: The Solo Non-Stop Voyage of the Mighty Sparrow may be even ...read more

01-1970-Dec

50 Years of SAIL

Back in early 1970, Bernie Goldhirsh and the recently founded “Institute for the Advancement of Sailing,” publisher of an annual sailboat and gear guide, launched something called SAIL. A half-century later, a look back at the magazine’s first few years provides a glimpse into a ...read more