Mastering the A sail - Sail Magazine

Mastering the A sail

Though asymmetric spinnakers date as far back as 1865, credit Australian skiff sailor and designer Julian Bethwaite with the invention of the modern asymmetric, which he tested and developed on his Australian 18 designs during the 1980s. Bethwaite needed a spinnaker with a long luff and flat leech on either gybe. This would enable crews to sail the skiff’s tight apparent-wind angles without
Author:
Publish date:
a_sail_diagram

Though asymmetric spinnakers date as far back as 1865, credit Australian skiff sailor and designer Julian Bethwaite with the invention of the modern asymmetric, which he tested and developed on his Australian 18 designs during the 1980s. Bethwaite needed a spinnaker with a long luff and flat leech on either gybe. This would enable crews to sail the skiff’s tight apparent-wind angles without collapsing the chute or sacrificing the sail power they needed to reach high speeds off the wind. That the sail, with its fixed tack and single sheet, simplified downwind sailhandling was an added bonus.

Twenty years on, the asymmetric spinnaker has developed into a versatile downwind sail for a wide variety of performance and cruising boats. Before boatbuilders could introduce the spinnaker on their racers, they had to devise a system for getting the sail away from the blanket of the mainsail while sailing on a low reaching course—not a problem on a skiff, which sails downwind at near-upwind angles. A common solution for this is tacking the sail on a retractable bowsprit; the J/105, in 1991, was the first to reach the masses with this configuration. To make the sail more versatile downwind, it is designed to be projected to windward of centerline, which helps a boat sail lower reaching angles.

Though it requires a small number of crew to handle—it has only one set of sheets, and in most cases no spin pole—compared to a symmetric spinnaker, an asymmetric chute still needs to be trimmed right when sailing a straight line and during maneuvers. To demonstrate, I went sailing with Dave Flynn of Quantum Sail Design Group in Annapolis, Maryland, and worked the 960-square-foot asymmetric on Rum Puppy, a J/105. The results were some tired hands, a few rips in the sailcloth, and the following photo guide to sail trim.

A-sail trim

Ease the spinnaker sheet until the luff of the sail breaks. Trim. Ease it again, trying to maintain a slight curl in the sail. It’s that simple, but only if the sail is set up right.

More than a control line you pull and cleat, the tackline is one of the keys to a well-trimmed spinnaker. Dave Flynn’s rule of thumb for a sprit boat, such as the J/105, is to ease the tackline if the luff of the sail is no more than 10 percent longer than the straight line from head to tack. This will help project more sail area to windward, allowing the boat to sail deeper angles (more than 135 degrees apparent) more effectively. As windspeed drops, lower the tackline and sail tighter reaching angles.

shoulders_a_sail
a_sail_luff
a_sail_leech
a_sail_tackline
twing_a_sail

Related

SWTR005_SWJK022

MPX Pro Offshore Jacket

Heavy Duty JacketMusto’s new MPX Pro Offshore Jacket features the same waterproof, breathable three-layer Gore-Tex fabric as its predecessors, but weighs 15 percent less. Changes to the hood make it easier to adjust and the fleece-lined collar and hood pod provide both warmth and ...read more

2018-BestBoatNominees

Best Boats Nominees 2019

As we approach the upcoming fall boat shows, perhaps the best word to describe the boatbuilding industry’s latest crop of new designs is “consolidation.” Specifically, in recent months we’ve seen a number of innovations introduced in years past continue to work their way up and ...read more

9781472947666

Book Review: The Atlantic Crossing Guide

Jane Russell & the RCC Pilotage FoundationIf you have a yen for sailing across the Pond to explore the delights of Northern Europe or the Mediterranean, you’d best do some homework first. There’s no better primer than this weighty tome, now in its 7th edition. It’s crammed with ...read more

shutterstock_63705382

Raytech Gelbox Line

Well GelledEvery so often you run across a product you never knew you needed, and then you wonder why it took so long for someone to come up with it. Thus it is with the Gelbox line from Raytech. These reuseable plastic boxes for low-voltage connectors are filled with gel, so ...read more

shutterstock_295810247

Cruising: Nova Scotia’s Bras d’Or Lake

I have rarely had a cruise that wasn’t different from my expectations, and my Nova Scotia travels have borne that out. For my friend and shipmate, Steve White, and me, our 2017 trip to Cape Breton Island and the Bras d’Or Lake on One Timer, my Sabre 362, was a much anticipated ...read more

ElanGT5-a

Boat Review: Elan GT5

Aboard many modern yachts, it can be hard to remember exactly what boat you’re on until your eye happens to light upon a logo. However, this is most definitely not the case with the Elan GT5, a performance cruiser with a look all its own and style to burn.Design & ...read more

01-Lead-P1060210

Handheld VHF Radios

For many sailors, cell phones have become their primary means of both ship-to-shore and ship-to-ship communication. Even the Coast Guard will often ask for a cell number after it receives a distress call. None of this, however, makes a VHF radio any less important—and this goes ...read more

Seascape24

Boat Review: Seascape 24

Since its inception in 2008, Slovenian builder Seascape, founded by a pair of Mini Transat sailors, has focused solely on creating boats that are both simple and loads of fun to sail. With their 18-footer and then a 27-footer they succeeded in putting out a pair of trailerable ...read more