Leaving in a multihull: under sail or power?

For the engines!

By Daniel Curt

Daniel Curt is a sexagenarian resident of La Rochelle whose brain has difficulty resting. Engineering fascinates him, once it touches on solar panels, geothermics and other ‘independences’ to be conquered, as the present day solutions don’t satisfy him! He has invested this creative ability in the design of two multihulls: a 50’ catamaran, with Michel Joubert, and a Power Cat 60’ with Marc Lombard!

To reply in concrete terms to the question ‘sail or power’? Here is the assessment (in the shape of a eulogy) of my Atlantic 60 (motor catamaran). After the launch in September 2009, a first test sail took us to Norway, via the Caledonian Canal (across the United Kingdom from the Atlantic to the North Sea), with the return via Amsterdam. Not a single mechanical problem; the transmissions, by toothed belt and horizontal propshafts (absence of the vertical component of the thrust), didn’t bat an eyelid, and to date we haven’t had to intervene once (a first-rate idea - Ed). This system has allowed me to offset the engines towards the longitudinal axis (centering and movement around the boat) and raise them to working level (I returned the two oil-change pumps to the supplier, we do it by gravity), reduce vibration, increase the reduction ratio by the diameter of the pulleys, and increase the size of the propellers. Marvelous, you will agree, and that’s not all. Let’s have a look at a simple, but instructive calculation: how much does a full rig for an 18-meter catamaran like ours weigh and cost? Obviously we’re not talking here about rotating carbon masts, exotic sails and electric or hydraulic fittings (and we’re ignoring the maintenance of all this equipment…the hassle of winter lay-ups, with the associated mold and birds' nests in the folds of the fully battened mainsail! Ours weighed 150 kg and therefore remained in position). As we are talking about handling, it used to take me 15 minutes to hoist this famous mainsail by hand (you should have electrified your winches, certain people will reply!). With the Atlantic 60, what does a lay-up in the Antipodes involve? We have to close the boat, and call a taxi to drive us to the airport, that’s all. Let's try a financial estimate of 200,000 euros for this rig and finish off our calculation: with this sum, last year in the USA, I could purchase 285,714 liters of diesel, which gives, taking into account our catamaran’s engines (two 6-liter, 180 hp Cummins turbos, whose consumption is less than 1 liter per mile at 7.5 knots), a range of: 142,857 miles. Compare this with a ‘little’ Atlantic crossing of 4,500 miles! Another relevant argument: I have just sold all my foul-weather gear on-line; I've lugged it from Norway to the St. Lawrence without ever using it (the pleasure of a real cozy, heated wheelhouse!). So, let’s sum up, the sailing catamaran has against it: the investment in the equipment, its compulsory maintenance, its life span and the maneuvers (notably ...