Trimming the Big Cat's Headsails
Trimming the Big Cat's Headsails
It’s easy to become enamored with the marvelous wings of the AC72, but wings are powerful and efficient. The headsails remain a crucial part of the aero package, which makes trimming them a challenge at high speed.
In the early days of Artemis Racing, we had a meeting with the boat designers. They had plenty of computing power, but no real-life experiences. The first AC45s were just starting to come out of the shed, and the AC72 existed only in concept. All the studies showed that in more than 12 knots of wind, the wing on the AC72 would be so efficient and powerful that a jib wouldn’t be required. They concluded it would only slow us down. Another sailing team member, knowing I was a jib trimmer, elbowed me and whispered, “You better start looking for something else to do.”
A short while later, we sailed an AC45 for the first time. It was windy, and as we turned into the wind for our first tack, the bows slammed into a wave, the boat stopped, and we were immediately thrown into reverse. With a jib to backwind during the tack we would’ve been fine. Phew. I still had a job.
Since then it has been proven that the sails in front of the wing are not only crucial for tacks, pre-start maneuvering, and other important boathandling, but that they’re also an integral part of the overall aero package. However, there are real challenges when trimming the headsails on these boats.
High apparent-wind angles
An AC72 or AC45 at full speed is very fast, which means the apparent-wind angles are always extremely narrow, and we’re essentially sailing in upwind-trim mode. Going “downwind” with the sails sheeted in took some getting used to. The sails are sheeted harder than you’d expect coming from a monohull world. The only exception, of course, is during maneuvers, where catamarans go from full speed to stopped and back up to speed again. We can be sitting closehauled with the sails out eating a sandwich, but the moment the helmsman bears away, the boat takes off. In the sail trimmer’s role, especially during the pre-start, this means we need to be ready to go from fairly soft trim to very hard trim in a short burst. Having a good feel for when the boat may accelerate to top speed is essential because it allows us to stay ahead of the game. Acceleration drills and real racing experiences are the best methods to understand and improve trimming.
No heel or feel
Whether we realize it or not, every sailor is constantly sensing a boat’s heel and making adjustments based on that feel, i.e., twisting off the main to depower the sail and flatten the boat to a heel angle that feels right. ACC yachts sailed upwind with heel angles of 25 degrees or more. That’s not the case with the catamarans. The highest stability and least amount of drag in a catamaran is when the windward hull is just clear of the water. If a team is good enough, they may sail an entire day between 3 to 10 degrees of heel. Trimming sails without this valuable sensory feedback is a challenge overcome only by time in the boat, drills, races, and productive debriefings. Lacking an internal heel sensor means we have to focus more intently on watching the sail, discussing it, and noting as a group how the boat feels.