SELECTING THE RIGHT DOWNWIND SAILS FOR YOUR MULTIHULL

Make Off-the-Wind Sailing More Fun!

Fast and fun off-wind sailing is what multihulls are all about. High speed, high stability and close wind angles require unique sail choices. Cruising multihulls in particular benefit from specialized sails that are versatile and easy to use. Understanding downwind sail types and selecting the right sail will help you achieve top performance from your boat and enjoy your time on the water.

The fastest sail on the market won’t do any good if it’s going to spend all its time down below on the bunks because it’s too difficult to use.

Sails for multihulls are not one size fits all. Figuring out the performance gaps, what the boat is set up for, what you already have are all important in determining what sails are best for you. We have a ton of options and we can customize to meet your needs.

Which sails are best for me?

That will depend on your experience and how your boat is set up, but it does help to understand the wind angles and geometry of downwind sails. We’ll discuss those in detail below, but first here’s a diagram that explains sail range:

What to consider when choosing your ideal sail

Wind Angles

Knowing the optimal wind angle for your boat is the first step to choosing the right downwind sail type. Wind angle is the single most important factor in downwind sail design, but the terminology can be confusing. Many sailors think in terms of True Wind Speed (TWS) and True Wind Angle (TWA). True Wind combined with Boat Speed creates Apparent Wind, which is what really matters for downwind sail size and shape. You can find your boat’s predicted Apparent Wind Angle (AWA) and Apparent Wind Speed (AWS) in the boat manufacturer’s Polar Diagram, or ask your North Sails expert to calculate it for you. Most cruising multihulls like to sail around 90° AWA in a range of true wind conditions. Faster boats will sail closer AWAs, while slower boats will sail wider AWAs. Your own experience will also help figure out your boat’s optimal AWA; just look up at your wind indicator when sailing in the “groove.”

Geometry

Multihulls offer unique opportunities for setting and sheeting downwind sails. The wide deck platform provides outboard sheeting points that makes downwind sails more efficient. Similarly, the windward hull provides a tack location when sailing deeper angles is desired. The wide shroud base also creates some downwind sail sizing and sheeting restrictions. Downwind sails are sheeted either inside or outside the main shroud. ‘Inside’ sails are generally optimized for AWA closer than 90° and are called code sails. ‘Outside’ sails are generally optimized for AWA greater than 90° and are called either gennakers or spinnakers.

Code Sails

Code Sails are flat, furling headsails that provide maximum power for light air and close reaching. Code Sails sheet inside the main shroud and are used at or near upwind sailing angles. Code Sails require tough, low stretch and lightweight material for durability, shape holding, and and ease of handling. If stored when furled, Code Sails may incorporate leech and foot covers. If your boat has a small upwind headsail and you need more power for upwind and very close reaching, a Code Sail could be a great addition. Code Sails can also be combined with ‘outside’ sails for a two-sail downwind inventory.

Sail Handling: Structural Furlers, Free Flying Furlers with Anti Torsion Luff Rope

UV Material: UV paint for select styles, UV material for heavier weight sails

Gennakers

G Zero Gennakers are the most popular cruising multihull downwind sail because they offer great versatility and cover a wide range of wind angles. G Zeros feature a deeper shape and wider girth compared to Code Sails, sheet outside of main shroud, and excel at beam to close reaching. G Zeros are compatible with all furling systems or can be used with a snuffer. All cruising multihulls benefit from added downwind sail area and the G Zero is optimized to provide easy to use sail power.

The most convenient thing about a G Zero is sail handling. Most of the time, it’s on a furler with a sun cover. It can be lightweight, and we can customize them for deeper sailing angles. They can also be built to sail as high as 60 degrees, which requires more stretch resistant materials and custom sail engineering. The G Zero is strong, and great for sailing fast in breeze.

What’s the design difference?

G Zeros have a higher clew. We’ll figure out the geometry based on measurements taken from your boat, as well as what type of furling gear you have, your sheeting angles, usage, and depth.

Main Points:

G Zeros are the most versatile downwind sail available in the widest range of fabrics. They are highly customizable, with many cloth and design options.

Sail Handling: Free Flying Furlers with Anti Torsion Luff Rope, Top Down Furlers, Snuffers

UV Material: UV paint for select styles, UV material for heavier sails (UV covers are not available for nylon or polyester spinnakers)

Asymmetric Spinnakers

If you are looking to optimize for deeper wind angles or plan to carry more than one downwind sail, North Sails offers a wide variety of asymmetric spinnakers. For example, the A4 spinnaker has broad shoulders to maximize sail area, while an A1.5 is designed to generate optimal downwind VMG. A G2 Gennaker is the go-to option to simplify deep running and lighter wind sailing.

Sail Handling: Top Down Furlers, Snuffers

Symmetric Spinnakers

The tried and true sail for dead downwind offshore is a symmetric spinnaker. Sheeted to the bows, this is a stable and extremely safe form of downwind sail power. Sailing dead downwind in the tradewinds offers self correcting directional course stability and better alignment with offshore swells.

Sail Handling: Snuffers

Why would someone have two downwind sails on a cruising multihull?

By filling a specific gap in the wind range and sailing angle, you’ll get the most efficient sail. Having only one downwind sail compromises either end of the range, so it’s best to cover your downwind sailing with two sail options.

Want to learn more on off-wind multihull sailing? Contact your North Sails experts today and get the most out of your experience. In the Southern Hemisphere, contact Ben Kelly at North Sails in Brisbane, Australia. In France, please contact Hugues Destremau based in Vannes. And if you’re in the Western Hemisphere, contact Bob Meagher and Peter Grimm, based out of North Sails in Ft Lauderdale, Florida.

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