La Tortue 147: the aluminium catamaran disrupting traditional yacht design

Inspired by space pirates and stealth aircraft, La Tortue 147 is a disruptive take on long-distance cruising. François Tregouet sails the radical aluminium catamaran that turned a childhood dream into an engineering project and work of art.

In a global market, you have to appeal to the widest possible audience with a unanimously attractive design, which you can produce in large quantities to be competitive. This seems like unassailable logic. But at this year’s International Multihull Show in La Grande Motte, it was an aluminium catamaran that disrupted this theory that attracted the most visitors.

From curious onlookers to design and naval architecture professionals, word spread quickly along the pontoons: La Tortue 147 was the boat to see.

La Tortue 147

While many shipyards present their latest innovations as a challenge to the status quo, this aluminium catamaran is the real deal. Its rebellious design brings both style and sheer audacity.

Its creator, Jean Sommereux, has transformed a boat he dreamt of as a child into a highly original project brief:

“A vessel as intelligent as space pirate Captain Harlock’s, more playful than a Playmobil pirate ship, and with the look of a stealth bomber aircraft!”

Sommereux may have retained a childlike spirit, but he is a seasoned entrepreneur with experience in industrial welding, petrochemicals and aluminium furniture.

This engineer’s mind is also sensitive to aesthetics and art, so he designed La Tortue 147 with his cousin, designer Jean-Michel Kalfon.

Kalfon is responsible for the distinctive ‘streaks’ on the windows, which are ‘more organic than organised’ according to Sommereux, and inspired by Marseille’s Museum of European and Mediterranean Civilisations, designed by the brilliant architect Rudy Ricciotti.

The inspiration behind La Tortue 147

It was in the south of France, during a three-year voyage aboard a beautiful 41ft schooner, that the idea for La Tortue 147 was born.

Sommereux did the maths: during his three years of wandering he had spent more than 95% of his time at anchor.

“That means I had the pot lid in my hand more often than the tiller,” he jokes.

This was the starting point for La Tortue 147’s radical build, a luxurious concept of a cruising boat where its creator would “live above the water, with a coffee machine and a computer, real green plants, a plancha grill, a fridge and, above all, my family, my friends and two or three good bottles of wine.”

The decision was made: the new boat would be not a hare but a tortoise, celebrating the true French art de vivre, or joy in living.

“A boat that’s easy to handle and accessible, so that I can sail at 70 or even 80 years old with my wife without scaring ourselves, and where we can welcome our children… that’s the boat of my dreams,” Sommereux explains.

To realise this dream, he set up a shipyard from scratch in Hergla, a small coastal town in the Gulf of Hammamet in Tunisia: “If you really want to control your quality standards, you need to have your own shipyard,” he argues.

Building La Tortue 147

Such an original boat would also have been challenging to build in a conventional shipyard.

While the design is disruptive, the construction is also far from ordinary. Sommereux grew up near the Meta shipyard, which built Bernard Moitessier’s legendary Joshua for the first Golden Globe Challenge in 1968.

So for him the choice of aluminium was a no-brainer for a boat intended for long-distance cruising.

Influenced by Meta’s Strongall process, most of the sheets are 8mm thick, whereas other builders are content with 6mm.

In addition to the obvious advantage of impact resistance, this reduces the structure and therefore the hard points, which should allow for smoother shapes.

Seeing the structure through the planking, as if it were transparent, is one of the aesthetic criticisms often levelled at aluminium boats.

For even greater safety, the entire forward section of the accommodation area is 10mm thick. In total, 10,800kg (23,810lb) of aluminium are used on La Tortue 147, representing 50% of the weight estimate.

As the maximum compression at the base of the mast has been calculated at 22 tonnes, the crossbeam has also been generously dimensioned, with a section of 750 x 1,300mm.

Disruptive design

Besides its construction, the hull is far from conventional in its lines, with bulges under the bows.

These increase the volume, allowing the engines to be positioned forward of the central beam, optimising weight distribution at a time when the trend is to move them aft.

This could reduce the pitching movements that are characteristic and often unpleasant in multihulls, though in the light winds we were able to sail in I couldn’t test the theory.

The rear skirts are as long as they are narrow at the waterline and just skim the surface of the water.

At sea, whether under engine or sail, the wake is minimal and silent. It’s a far cry from the washing machine swirls of some designs with their voluminous, wide submerged sterns.

The rigging is very slender, with no roach on the mainsail, which furls up the mast.

The intention here was to secure the rigging to the three levels of spreaders attached to the solid central beam. This frees up the side decks and avoids the need for fixed backstays at the stern.

The reasoning behind this is particularly extraordinary.

As a fan of motor paragliding, Jean wanted to be able to take off from and land on the deckhouse of La Tortue 147.

Given the risks of such manoeuvres his friends and family eventually dissuaded him from trying it, but the rigging remained as originally designed.

The same goes for the rigid flybridge bimini, which folds away to form what would have been the runway.

Onboard comfort, reimagined

A single step up provides access to an originally thought-out interior space. On the port side is a cloakroom-like area, you can leave your personal belongings for the day within easy reach in a locker – an excellent idea.

Forward, there is direct access to the galley. On the starboard side, the master cabin with a transverse bed has private access to the transom for morning swims.

In the centre, the cockpit is like a nest suspended above the water. On one side is a table that can seat eight guests, and on the other a plancha grill.

The sole is made of Paulownia wood.

The tortoiseshell patterns are very attractive, but this wood – although environmentally friendly – requires too much maintenance outdoors and will be replaced, perhaps with cork, on future models.

Inside, once you pass through the central bay window, the same wood contributes to the boat’s overall ‘wow’ effect.

Not only is the volume impressive, but the stripes also make an impact, While the harmonious colours of the woodwork create a serene atmosphere.

There are three levels in this nacelle, which helps to define the different areas.

The starboard bench is slightly raised for a better view, and its platform conceals plenty of storage space.

One side of the long (2.43m) galley worktop is set back from a step, making it ergonomic in relation to the large portside storage unit. On the saloon side, you can sit as if at a bar, or help the cook.

Forward, the panoramic chart table has a suspended seat straight out of a space shuttle.

However, a single opening porthole in the front window is a little small for proper ventilation in hot weather – the boat is fully insulated with 40mm/1½in of XPS foam above the waterline.

Three further cabins include one nestled in an alcove on the deck at the front on the port side, and another further aft, which share a central bathroom. The last is at the front on the starboard side, above the engine.

Carrying a load

The engines are located at the bow, which requires relatively long propeller shafts, but these are well secured in the fixed keels. The engines are easily accessible via a deck panel from the large foredeck.

However, accessibility is not the strong point of the helm station located at the rear of the deckhouse on the port side.

The aluminium steps are a little steep to descend quickly, but there is room to change their configuration on future hulls.

In keeping with the tortoiseshell theme, the wheel is hexagonal rather than round. Visibility is good from the helm station, but to manoeuvre you have to climb up onto the deckhouse – a flaw that, again, can be corrected.

Covered with solar panels (5.5kW), this rooftop also features a bench seat and a flybridge table, under the retractable rigid bimini top.

Lack of wind meant we were unable to really test the sailing performance of this unusual vessel, but with a sail area ratio of 10.5m² per ton of displacement (most catamarans sit between 8 and 8.5m²/t) it should be sprightly.

But from the outset, the watchword for this round-the-world boat was that it had to be able to carry a load.

For autonomy, there is tankage for 1,200lt/264gal of water, even though there is a watermaker, the same of fuel, and 20kVA of lithium batteries.

The boat will also carry plenty of toys, from diving bottles to paddleboards.

La Tortue 147 has broken the mould, but it remains to be seen whether critical acclaim can translate into a business model. Turning enthusiastic reception into sales is the challenge facing the Cataruga team.

But, as with the catamaran of his dreams, Jean Sommereux is not short of ideas – suggesting, for example, the idea of a shared round-the-world trip.

We wouldn’t mind spending a few weeks on board sailing across the Pacific…

 

 

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