Long range power catamarans

Peter Brady provided a brief history (Multihull World Magazine, #142) of how he saw the development of long distance power catamarans:

Arthur Defever 1960’s (“long range cruising” monohulls) –>
Robert Beebe 1974 (“passage maker” monohulls) –>
Malcolm Tennant 1990’s (catamarans) &  Roger Hill 1990’s & Peter Brady 1990’s in Australia (catamarans).

To this, the production capability for power catamarans really took off when the French company, Fountaine Pajot, started their prolific line of “trawler” yachts in the last 1990’s, continuing to this day.

The qualities of the “passagemaker” were defined by Beebe as 2,400nm range at 7.5kn, self-sufficient for at least two weeks.

Brady opines that 2,000nm at displacement speed is a “reasonable bench mark”, with 55-65′ boats making 8kn at “displacement speed”.

This “displacement speed” indication is perhaps a better metric and allows calculation of the standard “hull speed” calculation of 1.34 x sqrt(LWL), with a “displacement speed” changing the multiplier from 1.34x to 1x or 1.1x (so a 49′ boat would average 7-7.7kn, a 64′ boat would average 8-8.8kn).

It is worth saying now that many trimarans and catamarans are acknowledged as NOT being limited by this theoretical hull speed as the formula is based on the hydrodynamic (wavemaking) properties, but hulls that are very narrow for their length (some say 8:1 or more on LWL:BWL) may instead be more limited by the interaction properties of the waves off each hull. There is not

So as a working definition, a passage maker or long range cruiser can be classified as being able to go at least 2,000nm on standard tanks at a speed of 6-8kn (depending on length, but 36-64′ covers most cruising size boats).

I have collected fuel consumption, displacement and size for quite a collection of power catamarans that I consider cruising boats. By this I mean they have considerable range and autonomy, have a displacement or semi-displacement hull shape, and can sleep at least two couples. This precludes the larger and smaller fast fishing boats (hull shape; range), patrol boats (comfort; sleeping), and all the smaller aluminium cats.

Based on the data I have collected, for production boats, these are long range passage makers:

• Sunreef 70 – range 3200
• Africat 420 – range 2800
• Fountaine Pajot 46 Cumberland – range 2100

and for non-production boats, these are those I can find enough data to support as long range:

• Tennant 66 Domino – range 7000nm+
• Tennant 60 Catbyrd – range 6000nm+
• Tennant 54 PH8 – range 3000nm
• Tennant 44 St John – range 2000nm
• Roger Hill 66 Tenacity – range 2500nm
• Roger Hill 66 Lola – range 3200nm
• Brady 17.5 Passagemaker – range 3200nm

By definition, these power catamarans (a mix of one-off and production boats) are not long-range:

• Fountaine Pajot 37 Maryland (with 75hp engines, not 150hp) – range 1500
• PDQ 41 – range 1500
• Pachoud 49 Solitaire – range 1250
• Fountaine Pajot 37 MY – range 1200
• Lagoon 43 – range 1200
• Horizon 52 – range 1150
• Fountaine Pajot 35 Highland – range 1100
• Fountaine Pajot 44 MY44 – range 1100
• Ligure 50 – range 1100
• Aquilla 48 – range 1050
• Fountaine Pajot 40 Summerland – range 1000
• Fountaine Pajot 44 Cumberland – range 1000
• Leopard 51 – range 1000
• Leopard 43 – range 1000

and those with less than 1000nm range at the requisite speed:

• Aquilla 45 – range 950
• Leopard 37 – range 900
• Fountaine Pajot 34 Greenland – range 900
• Aspen 120 – range 750
• PDQ 34 – range 680

So it’s rather obvious that if you want a long range passage making power catamaran, you have three choices in production boats. I believe the Sunreef 70 is still in production. Africat had at least 31 hulls (as at 2010!), the Cumberland certainly has a few around, and at the upper end of length there would be a few secondhand Sunreef’s coming through the charter fleets. This means there is a reasonable list of production boats – even if only three designs – to choose from.

Going non-production, you are generally into one-off builds. Even though the big-name designers may have sold multiple hulls of the same initial design, these are often modified over the build so that they may only partly resemble each other once finished.

However…It is rather small-minded to ignore the fact that today there are more options to do passage making. For example the Silent 55 is a solar-assisted, pure electric or hybrid diesel-electric power catamaran that can passage make at 100nm per day on solar alone – essentially forever (at only 4kn though). Or it can go at 6-8kn combining both solar and diesel (range is uncertain, but with 600L diesel for the genset combined with daylight solar, it should be over 1000nm). So here is a passage maker that can go faster for short distances, or essentially has an infinite solar-powered range at lower speed. This tradeoff is something that DeFever, Beebe and maybe even Tennant probably couldn’t have imagined.

Lastly, the technical list of non-long range power catamarans ignores the fact that all of those referenced have an excellent range of at least 900nm. There are few times in a passage maker’s travels where more range is needed – the Pacific (Panama-Marquesas) and Atlantic (Bermuda-Azores, Cape Verde-Barbados, Cape Town-St Helena) are such, but these are an extremely small part of the time on water a passage maker spends compared to being close to land and places where diesel – quality or not – is available.

The options available are borne out by the travels of the Leopard 37, which are delivered to the Caribbean on their own hulls from South Africa even though they have a nominal range of 900nm only. They did passages of over 2500nm at 7kn in the most efficient fuel zone, a single engine at a time, and using extra tankage which make such long passages quite feasible for the few times they are needed. Some may argue that the fuel consumption figures are for calm flat water with no tide and thus theoretical and impractical as far as passage making in concerned: the delivery of the Leopard 37 should put that to rest as they encountered a variety of conditions in the Southern Atlantic including 35kn winds. Also, while it is true that careful choice of route and conditions are sought to cope with the fuel and boat size, this would be true of most any boat, monohull or multihull. Perhaps only Domino, Catbyrd, and Dashew’s FPB’s would consider conditions and routes others would not dare – but they are in a breed by themselves, perhaps a “super passage maker”.

As a final warning, almost all of the above it theoretical waffle. It doesn’t take into account some vital points of decision: is the boat designed and built to handle the conditions of a long passage? Are the people aboard capable and ready for such voyages?

If you know of other long range power catamarans and can provide at least three data points of speed-consumption, please let me know and I can add them.

Other interesting articles about power catamarans are:

• Shuttleworth on his Adastra
• Some of Malcolm Tennant’s ideas
• Alex Simonis on the Leopard 43 and why Power Catamarans Don’t like to go Uphill
• Noah Thompson on hull fuel efficiency

and for some first hand information, Domino and SnoDog are fantastic.