Spinnakers fall into three broad categories; Racing Asymmetric, Racing Symmetric, and Cruising. In each of those there are different options depending on the intended conditions, both wind speed and wind angle, which you want to use the sail in.

Let’s start with a basic understanding of how spinnakers are designated, what the “codes” mean. Even number sails are running sails, designed for use when you are trying to sail as deep as possible or when the course dictates sailing at an apparent wind angle greater than 90 degrees.  Odd number sails are reaching sails, generally designed to be used with apparent wind angles of 90 degrees or less. The higher the number, the more wind they are made for. The exception to this is the Code 0 which is designed for extremely tight reaching and will be made with the minimum mid-girth allowed to still be a legal spinnaker. These numbers are used for both asymmetric spinnakers and symmetric spinnakers. A medium air sail designed to be used downwind would be either a Code 2A or a Code 2S.

In light air, generally under 7 or 8 knots most boats achieve their best vmg by sailing quite “hot” so that the apparent wind is forward of 90 degrees. The higher apparent wind angle produces higher apparent wind speed and the boat will gain enough speed to more than make up the difference in the extra distance sailed. This is the area that an asymmetric Code 1A can provide big benefits. You cannot achieve the same result with a symmetric spinnaker because that sail by definition has as much curve in the leech as it does in the luff which prevents it from being a very good reaching sail. The asymmetric Code 1A on the other hand is asymmetric in shape and has a rounder luff while maintain much straighter and flatter sections in the leech for better reaching.

The Code 2 sails are made to be used with the apparent wind generally between 90 degrees and as deep as your boat can sail efficiently and in 7 knots of wind to 20 knot of true wind. This would be considered your “All Purpose” spinnaker. Whether you choose an A2 or a S2 will depend on how you boat is rigged and what you are rated for. Next in line is a Code 4; this is a full size sail very similar in shape the Code 2 but made of stronger material and designed to be used with the wind aft of 90 degrees when it is blowing over 18 knots. If you sail offshore, or in very windy areas you may also carry a code 6 which is a smaller and fuller sail designed to be used when there is too much wind to carry the full size code 4.

While the Code 1 is designed for light air vmg sailing it is also the sail of choice any time you are sailing a course that requires you sail on a reach with the apparent wind less than 90 degrees and when it is light enough to sail with a full size sail. As the wind builds and a the Code 1 is over powering  the next sail you would use is the Code 3. This again is a reaching sail but is flatter and smaller than the 1A. It is the reaching sail that is generally used with the wind between 11 and 18 knots. In more wind you would use a code 5 which is even smaller. The specialty Code 0 spinnaker is an asymmetric that has a mid-girth as small as the rules allow, for most cases this is a mid-girth which cannot be less than 75% of the foot. It is designed to be flown with the apparent wind between 40 and 60 degrees when the wind is light enough to not over power the boat. As with any of the reaching sails the actual conditions where you can use them will change with the wind speed. In 12 to 15 knots of wind your probably won’t be able to carry a Code 0 at 40 apparent because it will just tip you over, but it will work well between 60 and 80. In 20 knots of wind you probably can’t carry a Code 0 much tighter than 90 apparent.

The same designs carry over to cruising boats except then most cruisers have no desire to carry 5 or 6 spinnakers, they don’t care about flying a spinnaker in over 20 knots, and if it is really light they would just as soon stay in their present anchorage for another day or turn on the motor. So the general purpose Cruising spinnaker is quite close to a code 2A with slight smaller shoulders so it is more stable and easier to fly. On boats over 40 feet they will often step them up one weight just for the extra durability, but remember that the time you are most likely to use it is when the wind is between 6 and 15 knots, and that is when you want a sail that is light enough to fly well.

So a general use chart is something like this:

Code 0: Apparent wind between 40 and 60 degrees

Code 1: Apparent wind between 60 and 90 degrees, 2 to 10 knots

Code 2: Apparent wind between 90 and and 140 , 8 to 20 knots

Code 3: Apparent wind between 60 and 110, 11 to 18 knots

Code 4: Apparent wind between 100 and 180, 18 to 30 knots

Code 5: Apparent wind between 70 and 120, 18 to 25 knots

Code 6: Apparent wind between 120 and 180, over 25 knots.