The last three years have been of great development for the A-Class catamaran.
These boats can now literally fly on the water thanks to new set of daggerboards and rudders. The difference between floating or flying means 4-5 knots difference in speed.
In compliance with rule 8.1 and 8.2 (“no part of each hull or hull appendages below the waterline shall be less than 0,75 meters from the centre line” and “that movable and retractable appendages shall be inserted from the top or be capable of being fully retraceable into the hull”) there have been developed Z-shape daggerboards in conjunction with L-shape rudders able to produce enough lift to make the cat fly.
Even the shape of the mainsail has changed. They took some area from the top of the rig and put it down. The goal of these “decksweep” main is to reduce list and increase performance when the boat goes in laminar flow regimes (almost always).
Because of these recent developments the way to drive the A-Class speed machine has also changed. Actually we have to trim the main continuosly, especially in waves, and steering. If we have flat waters, we can lock-in our trim and simply adjust with the steering.
By trimming the mainsail on and off we basically put or release some downward pressure and weight on the boat. So, if the bows go too high i sheet the main in, otherwise i sheet out to get out of the water. With the steering we balance the boat when in “flying mode”.
These new breed of A-Class cats are equipped with sliding daggerboard cases. We can increase the lift simply moving backward the daggerboard and so we can use different settings for different conditions. We can also increase or reduce lift by changing the position of the body. Even the way to use the traveller is changing: 20-30 cm from the centre going downwind is enough. These catamarans can bear away much more then classic A-Class when flying downwind.
The development are still running and i can’t even imagine what the future holds for these class of catamaran, the best has yet to come…