2 min read · Updated 19 May 2026
The A3 is a medium-to-heavy-air reaching asymmetric spinnaker — flatter and more strongly built than the light sails, designed to keep a yacht powered and controllable across the wind once the breeze is up. It is the breezy-reaching counterpart to the light-air A1, and an important sail for fast reaching legs in the downwind sail wardrobe.
What the A3 does
Reaching in a building breeze is one of the most demanding angles for a spinnaker. The apparent wind is well forward and strong, the loads are high, and a sail that is too full or too light will overpower the boat or collapse and refill violently. The A3 answers that with a flatter cut and heavier cloth: enough shape to drive hard across the wind, but flat and strong enough to stay stable and controllable when it is windy.
On a fast boat, a well-set A3 turns a breezy reach into the quickest, most exhilarating sailing of the race — the boat lit up and planing across the wind with the sail pulling hard and steady.
Where the A3 sits
Following the convention that odd numbers reach and even numbers run, with higher numbers for more wind, the A3 sits between the all-purpose running A2 and the heavy-air running A4. A crew chooses it when the leg is a reach and the breeze is up — conditions too strong for the A1 and the wrong angle for a deep running sail.
Like every asymmetric, it is set and recovered using the techniques in spinnaker hoists and drops, flown from the bowsprit. How many of these sails a boat carries depends on its rules — a strict one-design limits the inventory, while an offshore boat may carry the full A1–A4 range. For the whole picture, see the sails pillar and the boat page.
Frequently asked questions
- What is an A3 spinnaker?
- The A3 is a medium-to-heavy-air reaching asymmetric spinnaker. In the standard naming system odd numbers are reaching sails, so the A3 is the breezy-reaching counterpart to the light-air A1 — flatter and more strongly built, designed to keep a yacht powered and controllable across the wind as the breeze builds.
- When do you use an A3?
- An A3 is set for reaching in moderate to fresh winds, where the lighter A1 would be overpowered and a deep running sail would be the wrong shape for the angle. It is a common choice for a breezy reaching leg, and on some boats doubles as a heavy-air all-rounder when conditions are too strong for the lighter sails.
- What is the difference between a reaching and a running spinnaker?
- A reaching spinnaker is flatter and cut to be carried with the wind more on the beam, on tighter angles. A running spinnaker is fuller and built for deeper, downwind angles. Reaching sails take odd numbers (A1, A3, A5) and running sails even numbers (A2, A4), so crews pick by both the angle and the wind strength.