The recipes for boat speed
Today, the relevance of multihulls to go fast in ocean racing is no longer in doubt. Catamarans and trimarans hold the speed records in transatlantic races and the Route du Rhum is no exception. But when you walk on the pontoons at the dawn of the start in Saint-Malo of the queen of Transat, you can wonder about the variety of forms present. Here is an overview, in the form of an illustrated history of naval architecture!
When trimarans were peaceful...
Honor to the great old ones. In the Rhum Multi category, there are a few plywood trimarans from the 1970s and 1980s, witnesses to the power of multihulls in offshore records, at the time of the victory for a few seconds of a certain Mike Birch during the 1st edition of the Route du Rhum . Happy, the sistership of the Canadian skipper's Olympus Photo, has banana-shaped floats, as pinched in front as behind, with their canoe-like shapes. Dick Newick, the leading multihull architect of the time, was directly inspired by Pacific pirogues and multihulls. The floats, shorter than the central hull, still had little volume and shapes not really optimized for lift. The Aile Bleue is in the same lineage.
When floats get bigger and boats get stiffer
Growing in size and popularity, trimarans have become larger. The floats got longer. As the speed of the boat increased and the width of the boat allowed it to carry more canvas, the floats became more substantial. The stiffness of the platform had to be taken advantage of. Since boats do not fly and daggerboards provide little lift, it is the float that provides the righting moment. The volume of the float is also the one that limits the risk of capsizing.
We can see it in the top of the floats of Trilogic, Multi 50 of 2004 or of Interaction of Erwan Thiboumery and even Charlie Capelle's Acapella.
Gliding and starting to fly the boats
To accelerate further, the shapes of the floats are evolving. The tension of the float lines is being worked on and flat surfaces in the back create lift. Some have already been trying to fit some foils for some time, like PIR2, launched in 1983, whose shapes can be confusing with its tulip-shaped bow.
The tension of the lines and the flat rear shapes can also be observed in the catamarans, even recent ones, lined up in the Route du Rhum, from Outremer to the ORC of Marsaudon.
Boats in the water, and above the water!
Among the recent trimarans, the Ocean Fifty, ex Multi 50, if they still have volume in the front, have taut rear shapes. Their foils relieve the float, without making the boat fly.
On the new Ultims, the way they work is changing. The boats are sailing flat, with the foil allowing them to regain power to fly rather than heel. The volumes have shifted in the floats, and the undersides are now very taut.
Looking at these photos, you can see how much ocean racing has evolved and you can imagine how the brains of naval architects and skippers have been racing in recent years!
