Downwind Sailing on a Cruising Catamaran

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Last Updated on September 28, 2020 by Amy

When we wrote our first sail trim for a cruising catamaran blog post, we were just about to move aboard Starry Horizons for our circumnavigation.  We’d been sailing a 30-foot Maine Cat around Galveston Bay, getting some sailing experience under our belts.  Starry Horizons is a pretty big leap, and we’ve learned a lot about sail handling since then.  There are two advanced sailing techniques that we’ve found very helpful when sailing deep downwind.

Flying Headsails off the Windward Bow

Our screecher is our favorite sail to use. It’s huge and when the wind is just right (like on the beam) we really get flying.  The screecher on the bowsprit is best used with an AWS of fewer than 15 knots, with an apparent wind angle (AWA) of fewer than 135 degrees.

We have sailed several times with the tack of our screecher (or spinnaker) attached to the windward bow of the boat instead of being attached to the bowsprit.  This allows us to sail at a deeper downwind angle (135 – 160). Instead of approximately 12 lateral feet between the tack and the clew (half the width of the boat), we are now using the full width of the boat to open the headsail even wider.

While the sail is still furled, we use a soft shackle to attach a low friction ring to the bow cleat.  Through the low friction ring, we run a new tack line.  The bitter end of the tack line goes through the clutch on the toe rail.  We loosen the clutch on the bowsprit to free the normal tack line. We detach it and pull the tack of the sail over to the new tack line.  You can keep both tack lines attached for added control. This allows you to adjust the position of the tack:  to the low friction ring at the bow, to the bowsprit, or somewhere in between.

Wing-on-Wind with Dual Headsails

We have sailed several times, especially on our Atlantic crossing, with our headsail and mainsail set to a wing-on-wing configuration.  It works, but can be troublesome depending on how light the wind is or how much the swell conditions are knocking the boat around.

Instead, we’ve flown wing-on-wing with both our screecher and genoa out.  The two sails combine to create one giant sail, and the wind funnels from one sail to another.  This is much more forgiving than sailing wing on wing with the headsail and mainsail.

We usually set the wind vane to 150 or so, unfurl the screecher, and then set the wind vane to 174. Then we roll out the genoa. The genoa is a much more forgiving sail, and its better to accidently backwind the genoa than it is to backwind the screecher.

Downwind Sailing in Higher Winds

As the screecher is not a sail that you can reef, when the apparent wind speed is higher than 15 knots, we sail wing on wing with the genoa and mainsail.  You can reef both sails as the wind picks up.

Monohull Notes

As you may know, David and I don’t have much experience on monohulls at all.  From what we gather, monohulls are not as comfortable downwave as catamarans are. This is a plus for sailing catamarans on a downwind circumnavigation.  However, when they do go downwind, we have several friend boats who sail wing on wing with the two headsails.  Putting poles on the clew of the sail to spread them out would be required.

Other Advice

When sailing with finicky sail configurations like the ones above, be sure to put your autopilot on wind vane mode and set the wind angle as a priority.  That way, if the wind shifts, your autopilot will adjust the boat to have the sails properly filled.  If you are running on a heading or a track when the wind shifts, you might find your sails backwinded or do an accidental gibe (which is dangerous).  Being on the wind vane setting does mean that you need to pay extra attention to your course; if the wind shifts, you may have to switch t another downwind sail tactic.

What have you found that works best for you while downwind sailing?

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