A spinnaker is a particular type of sail designed for use when a boat is reaching or sailing ‘off the wind’. For example, when on a broad reach or run. Like other sails spinnakers come in different sizes and it is not uncommon for a race boat to have two, three or even more spinnakers as part of its sail wardrobe.
On the water, spinnakers usually stand out as they are usually bright in colour and as a rule they are the largest sail on the boat. The larger the sail, the more wind a spinnaker can harness and so the more power may be provided. However, as spinnakers are generally relatively light in weight (usually defined by the weight of the fabric in ounces per square yard - e.g. 16 oz) it is important to understand the implications of flying it in overly windy conditions as when spinnakers tear they tend to tear catastrophically!.
Most race boats will have a variety of spinnakers (generally referred to as kites) with a large, lightweight kite for light airs and a smaller, heavier weight kite for heavier airs. As with other headsails, they are generally marked as 1, 2 or 3 with the larger, lighter weight kite being referred to as the 1.
Of course, in addition to size and weight of material, it’s also worth noting that spinnakers come in different shapes, dependent on whether the kite is to be used when on a beam reach or a deep broad reach. Some kites are cut to accommodate different points of sail and the standing and running rigging on any particular vessel. They are generally referred to as Asymmetric or Symmetrical spinnakers.
Spinnakers are generally rated to a maximum apparent wind speed and it’s worth noting that as one sails higher on the reach the apparent wind increases, sometimes significantly, meaning that a change in point of sail may require a change in kite size or shape.
Many sailors are intimidated by spinnakers, primarily because when things go wrong they can go wrong quite spectacularly but, with a little preparation and a well-briefed crew, flying a kite can be great fun and also get you where you want to go much much faster!
At Jolly Parrot Sailing we periodically offer sailing masterclasses to more advanced students which include the use of spinnakers and heavy weather sailing techniques (dependent on weather conditions).