A nostalgic look back to the 1980s will reveal that Prouts, Snowgooses, Blue IIs and Louisianas were the cutting edge of cruising multihulls. Between 10 and 11 m (34-36’), with their fitted-out nacelles, they were like superyachts for those of us who’d been sailing Hobie Cats. Here at the magazine, we have fond memories of a young couple who, in the mid-1990s, reached BoraBora from Antibes, France, on a Corsair F31. Today, they’re still sailing, and for the third time around the world... but are now aboard a 55-foot catamaran! Representative of the impressive increase in the average size of our multihulls, you might say?
Choosing the longest multihull possible, within your budget of course, is not just about being the fastest or being able to accommodate more people aboard. No, while length is an essential component of speed (see inset), it above all improves passage through the sea, tends to reduce pitching if the weights are well centered around the boat’s center of gravity, limits the risk of burying the bows if this same center of gravity is well aft, makes the bows and their spray further away, raises the nacelle, and so limits the impact of the waves... In short, length makes sailing safer and more comfortable.
So why don’t we all sail a 60-footer, or more? It’s a question of budget, of course. With length, the price increases exponentially - it is related mainly to volume and sail area. The first few feet are already expensive, but above 50 feet, the price increase is even greater. Purchasing power has certainly increased in some favored regions over the past couple of decades, but not enough for many sailors to be able to afford multihulls costing several hundred thousand euros.
The fact remains that the craze for ever larger multihulls is undeniable. Materials, structural calculations and naval architecture in general have made enormous progress: they enable large multihulls to be built with impressive reliability. And that’s good, because the human being has evolved very little in terms of his physical capacities. It even seems that our physical capacities have tended to follow an inverse course to our purchasing power over time...
Fortunately, technology, largely derived from ocean racing, has accompanied and encouraged this growth: infallible autopilots, furlers, spinnaker socks, lazy-bags, automatic reefing or even electric winches assist us for our greatest pleasure, comfort and safety. But when it’s time to enter a marina, or taking the gennaker weighing more than 100 kg (220 lbs) out of its sail locker, recovering a maneuver that’s gone wrong, all this technology won’t help us much.
So yes, apart from this bundle of converging factors, you only have to study the manufacturers’ production figures to realize that everything now seems to be played out around 45 feet. Why is that? It’s another story of compromise. It’s a size that remains reasonable and therefore manageable with a short-handed crew. The budget is certainly high, but not yet on the steepest part of the curve. All programs will find their happiness there. All the equipment essential for the circumnavigators of the 21st century will find its place on board, without becoming an unwieldy beast requiring the permanent presence of a professional crew in charge of its maintenance. However, the list of this equipment is growing year after year: watermaker, a number of solar panels, a well-powered RIB, kite and paddle boards, satellite dish...
And yet, don’t they say “small boat, small problems”? Doesn’t the planet push us a little more toward reason and simplicity? Isn’t happiness above all to actually sail? A small trailable trimaran, a 35-foot catamaran that you can push by hand to clear the pontoon, a sports catamaran for coastal camping: happiness at sea doesn’t depend on the number of feet. Nothing rational about it and it’ll make you happy!
The length and speed formula
Max hull speed = √((waterline length x g) / (2 x pi)) x 3600/1852 g = 9.81m/s² (universal gravitation) The Elements of Boat Strength: For Builders, Designers & Owners – Dave Gerr / International Marine
Be careful, don’t confuse this hull speed with maximum speed, which can be much higher, with one hull slightly lifting, or surfing down a wave. Moreover, if length is an essential element of speed, it is of course not the only one: hull shape, displacement, sail area and... the skill of the helmsman!
