Catamaran, Learn to Sail

Learning to Sail: The Asymmetrical Spinnaker

Spoiler Alert: This post has some geeky sailing language. To help all you beginners we’ve put a glossary at the end of this post. (We’re nice like that.)

The asymmetrical spinnaker is our favorite sail.  It is used for sailing downwind and you wouldn’t want to sail a cat without one.  So what is this fancy sail?  It is a spinnaker designed to be deployed typically from a bow sprit or the windward bow of the boat. This is unlike the conventional spinnaker that is symmetrical in shape and sheets are attached to both clews of the sail and designed to be sailed when the wind direction is further aft.

So why are they great on a catamaran? Many cruising cats are a bit heavier with more creature comforts and are happier sailing with a stronger breeze both upwind and downwind. Since on AlyKat we’re not fans of motoring  this sail allows us to sail in lighter breezes and maintain a respectable, if not very fast, speed. Basically in light winds the boat will sail well at 90 degrees apparent wind. As the wind speed increases it is very important to bear off the breeze to 120 degrees for moderate wind and 150-160 degrees for stronger breezes. Otherwise you can overstress the spinnaker and run the risk of it self destructing.

Typical speeds in our boat in lighter winds, say 8-10 knots, sailing at 90 degrees apparent wind, we will sail between 6-7.5 knots.  Not bad when most cruising cats will be motoring in this lighter wind.  My wife and I have sailed in 20 plus knots of breeze at 150-160 apparent and reached speeds of 13-14 knots surfing the waves.  It’s very important to make sure you are sailing with your mainsail in this wind as you can always dowse the kite by heading dead downwind and have the mainsail blanket the spinnaker making it easy to drop.  Another import feature when using this sail is to have a retrievable “sock”. This makes it much easier to deploy or dowse the spinnaker. Also, when jibing the spiniker in heavier breeze,  It is helpful to bear off dead down and “sock” the spiniker before completing the jibe.

We save many engine hours by having the bow sprit and asymmetrical spinnaker. It is my favorite sail on the boat and personally would not want to own a cat without one.

Sailing Lingo for the Newbies on Board

  • Asymmetrical Spinnaker: A specialty sail used on racing boats, bridging the performance gap between a genoa, which develops maximum driving force when the apparent wind angle is between 35 and 60 degrees, and a spinnaker, which has maximum power when the apparent wind is between 100 and 140 degrees.
  • Clews: the lower or after corner of a sail.
  • Aft: towards or at the back part of a boat, ship, or airplane
  • Apparent Wind: “Loosely defined, apparent wind is the wind we feel and experience when we are in motion. It’s a combination of the actual wind (true wind) that blows over land and sea and the wind created by our moving forward.” –Sailing Magazine
  • Sock: Not to be confused with “sock-it-to-me,” a sailing sock is a long fabric tube that stores the spinnaker and allows the spinnaker to be deployed and retrieved easily. To “sock the spinnaker” means to put it away.
  • Jibing: “A sailing maneuver where a boat reaching downwind turns its stern through the wind, such that the wind direction changes from one side of the boat to the other.” – Wikipedia
  • Dowse the Kite:  sailing speak for taking down the spinnaker.

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