Cruising on a Power Multihull

The Power Multihull sector has experienced a remarkable boom in recent years - few sectors in the boating industry can boast double-digit growth. In this buyer’s guide - which has become a special motor issue over the past two years - no less than 120 models are presented. Out of all these 15 to 100-foot power multihulls, almost all of which are habitable (we have deliberately stopped at 100 feet), the category we have chosen for this issue is the 40 to 50 footers. These models already have most of the attributes for a successful summer or long-distance cruise. Charter companies like Sunsail/The Moorings operate powercats from 43 (soon to be 40) to 53 feet. In this issue’s buyer’s guide, the seventeen 40 - 50 foot power multihulls are all catamarans equipped with two engines whose power ranges from... 90 to 860 HP. By filtering out the most extreme engines (including outboards), we arrive at a convergence of between 250 and 400 HP inboard. We will use this order of power as a benchmark to help us understand how to limit fuel consumption under way.

Two hulls are better than one!

These benefits begin, as we mentioned above, with powercats having a much more frugal appetite than their monohull counterparts. When under way, the drag of two thin hulls is much lower than that of a single wide hull, and this leads to much lower fuel consumption. If we compare a powercat with a boat of the same volume, the evidence is conclusive. Prestige Yachts, which recently arrived on the power catamaran market, would not disagree. The Prestige 590F burns about 30% more diesel than the brand new M48, which requires just 12 gal (45 l)/h at 10 knots and 20 gal (75 l)/h at 14 knots. Yet the powercat has a similar livability despite being 11 feet shorter. It should be noted that the M48 manages with two 320 HP engines while her big sistership requires two 600 HP units. However, the monohull has an advantage when it comes to its top speed - it can reach nearly 30 knots, while the M48 will not go faster than 20 knots. Also worthy of note is that while in the past, a top speed of more than 20 knots was a determining factor in the purchasing decision of boatowners, this trend is rapidly disappearing.
For the first models of our target category, the advantage in terms of consumption in favor of powercats remains. If we look at a Sedan version with minimal windage like the Fountaine Pajot MY4.S, the two 250 HP engines consume 6.6 gal (25 l)/h at 11 knots while the Bavaria E40 trawler, with its 2 x 300 HP, burns 8.7 gal (33 l)/h at the same speed. At 15 knots, once the schedule is set, the on-board instrumentation will show respectively 10.6 gal (40 l) and 13.2 gal (50 l)/h - that is to say a 20% fuel saving for the catamaran, which is considerably more welcoming for its passengers.
Let’s close this comparison between powercat and monohull with a brief incursion into the top of the range, well beyond our 40-50 feet. On board a Fountaine Pajot 67 Power equipped with a ...