On board Tara, from Tokyo to Hawaii (week 2)

The antimeridian. The line, opposite Greenwich, which is both 180° East and 180° West. The one that changes the date. The schooner Tara crossed it without any particular ceremony last Sunday night on its Pacific route between Tokyo and Hawaii. Only the coordinates φ and G recorded in the logbook testify to this passage from the East to the West. Since leaving Japan, the time has already been brought forward three times and as they approach Hawaii, the crew is preparing to experience the same day twice. The features are a little drawn and the awakenings, nocturnal and diurnal, sometimes difficult.

Tara crossing the Pacific (© MER ET MARINE – CAROLINE BRITZ)

“Me, I don’t care about all these time changes. My samples live in universal time”. Fabien Lombard, the scientific manager during the crossing, closes the trunk stowed on the bridge. Inside, there are already dozens of plankton samples. Others are stored in liquid nitrogen. After a difficult start, due to bad weather conditions that shook both the boat and the scientific team, science is in full swing aboard Tara.

Fabien (© SEA AND MARINE – CAROLINE BRITZ)

Every morning, it’s the same ritual. The starboard crane was overwhelmed and the Dolphin launched. The Dolphin, an invention – like all the other plankton sampling devices on board Tara – of researchers from the Villefranche-sur-Mer observatory, is used to suck up surface water. Deployed for one hour, it “sends” four cubic meters of water per hour via a peristaltic pump, which guarantees a lower level of contamination than a conventional pump. A first filtering at 2 millimeters, aiming to retain the largest organisms, is carried out before arriving at the wetlab, the laboratory installed on the deck. The water then passes through a 20 micron filter which will allow plankton sampling.

The Dolphin (© SEA AND MARINE – CAROLINE BRITZ)

Fabien and Hiro (© SEA AND MARINE – CAROLINE BRITZ)

“The idea of ​​the Dolphin is neither more nor less than a scoop connected to a decknet, a sort of dry net. This allows us to sample continuously with a 20 micron net which would tear very quickly if dropped into the water at cruising speed”. The water collected in the decknet collector will be separated into several samples with different fixings: lugol to tint the phytoplankton, formalin and ethanol for genetic studies. “Ethanol allows the preservation of DNA. We inject a first dose when sampling, we let it rest overnight while the organisms release water and we give a second dose so that it can be sent in the best conditions to the Roscoff observatory”. Another sample will be examined directly on site using the flowcam, a camera that allows the photography and recognition of the different species of plankton collected. After being studied, these images will notably join the gigantic free access database EcoTaxaset up by the Villefranche-sur-Mer observatory.

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Squared, science and navigation come together (© MER ET MARINE – CAROLINE BRITZ)

(© MER ET MARINE – CAROLINE BRITZ)

Around Tara, the ocean begins to take on a beautiful indigo hue as the road descends to the south. After the first tumultuous days, the wind and the swell have calmed down. A little too much perhaps for the taste of Yohann Mucherie, the captain who never really takes his eyes off the sails. Eole hasn’t really been one of us since leaving Tokyo. After the low pressure that accompanied the first week, the schooner is now forced to sail into the wind, which makes it difficult to use the sails. So we try. We hoist then lower when the sails start to flap, a sign of their unwinding.

Yohann, the captain (© SEA AND MARINE – CAROLINE BRITZ)

Tara’s autopilot is programmed to keep a constant angle to the wind, meaning that if the wind turns, the boat will follow. But this road is not necessarily the one we should take. Every quarter, it’s the same thing. We look on the map where the wind is pushing us, we compare the trajectory with the orthodromic route, the shortest, and the loxodromic route, that of the constant heading. Keep the sails high? Lower the mainsail and keep the foresail? Push the engines? Shooting down, gaining a bit of speed and losing course? Navigation here is a matter of compromise and strategy. With two goals: to create the best possible conditions for science sampling and to arrive on time in Hawaii, where a team of coral scientists will embark for a week of sampling in the archipelago.

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Sophie with the crane (© MER ET MARINE – CAROLINE BRITZ)

On deck, Hiro, a Japanese scientist, listens carefully to Sophie Bin, the chef. She does not give him culinary advice but teaches him how to properly coil the end of the starboard crane. Because it is she who, alongside Fabien and in relay of the sailors, handles the handling of the crane and the rear gantry which are used to launch the various scientific sampling instruments. “Everything interests me on board the boat, and what’s more, it allows me to lend a hand to the crew”, she smiles, always ready to jump into her boots. Good will is undoubtedly the secret of a small crew for whom versatility is second nature.

Hiro (© MER ET MARINE – CAROLINE BRITZ)

The sea water is warming up. At the machine, the temperature of the floors already reached 45 degrees. “We have already seen a lot more when we sail in tropical waters”. Loïc Caudan, the chief mechanic, readily explains the nooks and crannies of his machine into which you have to sneak headlong. The machine, on board Tara, is much more than propellers and propulsion motors. It is a whole circuit of energy organized and permanently adapted to the service of science. With, to begin with, very specific electrical needs. The lab’s tens-of-thousand-dollar machines and the data they collect could not suffer from prolonged power outages. So we created a dedicated power supply circuit.

In the machine with Loïc (© MER ET MARINE – CAROLINE BRITZ)

In the machine with Loïc (© MER ET MARINE – CAROLINE BRITZ)

On board Tara, there are three generating sets connected to a 230 V switchboard. In addition to most of the current electrical distribution on board, this supplies chargers which serve two battery banks: one dedicated to the launch of the main propulsion and the other for the service. “It is the latter which will supply the ‘stabilized’ energy needed for science by supplying a 24 V switchboard, retransformed by seven inverters which provide a current of 230 V”, explains Louis Wilmotte, who in addition to his duties on the bridge, knows perfectly the electrical network on board.

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A complex organization, which is the result of a permanent adaptation of the boat to the different expeditions. Loïc followed the preparation site for the Tara Pacific expedition. “As always, we modified the boat to be able to meet the needs of the scientists. We have, for example, modified the accommodation to be able to install a drylab in the middle of the cabins”. New installations to collect aerosols in the aft hold, adaptation of the installation to the different machines used, compression for the diving cylinders… the Tara team must constantly re-imagine a boat, which, basically, has was designed to be trapped in the ice. “Scientists tell us what they need, we try to do the best. After all, everyone adapts to the constraints”. And if Tara is not the largest of oceanographic vessels, it compensates for its limitations with its flexibility.

Collection of aerosols (© MER ET MARINE – CAROLINE BRITZ)

The HSN (© SEA AND MARINE – CAROLINE BRITZ)

Charlene, second captain (© MER ET MARINE – CAROLINE BRITZ)

Night has set on the deck of Tara. The last HSN, the high-speed net, was raised: at the bottom of the collector, we found velles, copepods, very small trevallies and a curious little pelagic blue crab. Charlène Gicquel, the second captain, goes up to take her watch. The sky chart and the tables of Dieumgard and Bataille are placed on the bridge. Charlène spotted Véga, Altaïr and Deneb. There are still a few beautiful peaceful nights to refine our astronomical point.

On board Tara, Caroline Britz, June 2018

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