ARION

Why a swing keel rather than a fixed keel?

A fixed keel with 3 m draught closes off the Patagonian caletas, shallow-water zones, tidal groundings. It rules out beaching, the technique of resting the boat on its bottom at low tide to service the hull or change a part.

The swing keel lifts, drops, modulates. Raised, it sits in the sump under the hull and draught falls to 1.3 m, we can go anywhere. Lowered, we have 3.2 m of lateral plane to claw to windward below 60°S.

The 5.2 t ballast is on the keel itself, not on the hull bottom. Versatile platform, performance preserved.

Why a cutter rig, genoa plus staysail?

In heavy weather, you don't change headsail by feeding a jib on a pitching foredeck. You roll the genoa in and unfurl the staysail, without leaving the cockpit.

Two furlers, two stays. Genoa for close-hauled and downwind up to 30 knots, staysail from 30 to 45. Beyond that, we heave to under a triple-reefed main or under storm jib. Most of the time, the cutter rig lets us reduce remotely, without putting ourselves at risk.

Why two engines?

The inboard handles daily propulsion: the original MWM, still in place. Replacing it with a more recent 115 hp engine is a target of the refit. A second engine is mounted on the stern platform on a reinforced bracket built for it, a 60 hp outboard with strong low-speed thrust and a 4-blade propeller.

In Patagonian channels, surplus power isn't a luxury. Caletas are negotiated slowly, against catabatic wind and current, sometimes through a single-passage channel. An engine that stalls under those conditions, and the boat goes sideways in thirty seconds.

With two engines, we free ourselves from ice traps that don't exceed a metre thick, we claw upwind against current, we pull off a shoal. Redundancy is what makes margin useful.

Why an oversized tender?

A 2.60 m plastic tender doesn't survive a 100-knot gust. It takes off like a kite. In those conditions, even the life raft isn't deployable before blowing away. We needed a different logic.

ARION's tender is 4 metres of aluminium, unsinkable by construction. Designed as a barge, you load it, you tow with it, you work on it. Built by students of a technical school in Chambéry.

It doesn't sit on stern davits, none would hold its weight with engine, fuel and gear. It rides on deck, deployed and retrieved by a custom cargo boom.

It serves for everything, complementary escape route to the life raft, pulling ARION off a shoal, deflecting a bergy bit drifting onto the mooring lines, fetching firewood in a caleta, carrying jerrycans. A tender on the boat's scale, it's not a gadget.

For the circumnavigation, nothing is decided. It may stay in Patagonia with the windlass, the 150 m of 12 mm chain and the three anchors. For the loop below 60°S, we take only what's strictly necessary.

1800 Ah lithium, is that a lot or is that just enough?

Just enough. Below 60°S, we consume 250 to 400 Ah per day across Starlink, radar, AIS, autopilot, electric backup heating, fridge, lighting, personal gear charging.

With 1800 Ah LiFePO₄ (around 1,440 usable in cycling, without the punishing deep discharge of lead-acid), we hold three days without production during a storm with no solar or wind input, which happens. Beyond that, the inboard genset takes over.

The real constraint isn't battery volume. It's cold protection, which blocks charging below 0°C. Insulated locker, temperature sensor, active management.

How do you keep warm at -25°C in a boat?

Three layers of defence. The aluminium hull insulated with 80 mm of sprayed polyurethane, anti-condensation coating on the floors, wood cladding inside. That already cuts half.

Main heating is diesel-fired forced-air, 5 kW, fed from a dedicated tank, around 400 hours autonomy. Blown into every berth and the saloon.

Backup heater runs on kerosene or wood, fully independent of the electrical system. If everything fails, it heats. You don't freeze to death aboard ARION as long as there's fuel.

Sixty days without port: how do you manage fresh water?

60 l/h watermaker, 12 V motor, 6 A consumption. We produce more than we consume even in overcast weather. Buffer reserve, two 300 l stainless tanks inside.

On the circumnavigation, we make water as we go. We use 10 to 15 litres per person per day, drinking, cooking, reduced washing. No showers.

Redundancy, if the watermaker fails, the 600 l reserve covers 20 days for two. Beyond that, rationing and rain collection.

Is Starlink reliable below 60°S?

Starlink Ocean covers the Antarctic circumpolar zone thanks to inclined LEO satellites. Below 60°S it works, with more frequent service gaps south of southern Argentina and in some South Pacific sectors.

Useful throughput 25 to 100 Mbit/s, enough for GRIB weather, emails, partner exchanges, transmission of scientific data. Not enough for streaming, we do without.

Mandatory redundancy, Iridium GO! as permanent backup. If Starlink drops, Iridium handles weather, emergency messages, position. Two independent channels, two operators, two different orbits.

Ice at night, how do you see it coming?

Raymarine Quantum radar, useful range 24 miles on large icebergs, 6 to 8 miles on bergy bits of 5 to 10 m. Below that size, radar struggles.

Growlers, ice fragments barely breaking the surface at 1 to 3 m, are the real trap. They don't return a radar echo, and aren't visible before 30 m to the naked eye, 100 m with a searchlight. At 7 knots, that gives ten to thirty seconds to avoid.

The countermeasure, reduced speed at night in ice zones (5 to 6 knots), systematic visual watch, forward-facing thermal cameras under evaluation for critical sectors. And some luck.

Which sails for heavy weather?

A simple wardrobe, maintained, predictable. Offshore main with three reefs, Kevlar reinforcements at the stress points, able to be fully dropped from the cockpit. 135% genoa on furler for 0 to 30 knots. Staysail on furler for 30 to 45.

Beyond that, dedicated storm jib hoisted on removable stay, 6 m². Main replaced by a trysail for running off bare or nearly so. Storm sails stowed in a numbered bag, accessible without light.

Rule: reduce before you need to. A sail flogging at 40 knots is a ruined sail and an exhausted crew.

Medicine at sea with two: how?

Three advantages. A full infirmary, basic surgery, broad-spectrum antibiotics, major analgesics, immobilisation gear, defibrillator. Standard polar-expedition equipment, validated protocols.

Medical competence aboard, Captain's medical training, Sarah's expedition-medicine training. No specialist, but enough to diagnose, stabilise, decide on a retreat.

Twenty-four/seven teleconsultation via Iridium or Starlink. A maritime medical service takes over on complex cases, remote diagnosis, emergency protocol. Knowing that below 60°S, extraction takes several days.

System freezing at -25°C, how to prevent it?

Through-hull valves in PTFE rather than brass, less seizing in the cold. Sea-water circulation jacketed, traced with backup heating on critical elbows.

Diesel treated with anti-waxing additive from the equator onwards, pre-heated circuit. Batteries in insulated locker with temperature sensor, charging is cut below 0°C (lithium freezes chemically).

Fresh water in interior tanks, not under the cockpit. Watermaker shut down and purged between runs to prevent freezing in the membranes. Every system has its winter protocol, documented.