Why a Strongall aluminium hull rather than steel?
Strongall aluminium, with high yield strength and 10 to 25 mm plating on the bottom, absorbs impacts without giving way, can be cold-repaired with the tools onboard, and does not impose the permanent fight against corrosion that steel does. For a long route in the South, it is the compromise that holds up.
Why a swing-keel design rather than a fixed-keel yacht?
Keel raised, draft drops to 1.3 m and gives access to the Patagonian caletas and to drying-out anchorages. Keel lowered, you recover 3.2 m of lateral plane to work upwind south of 60°S. The 5.2-tonne ballast sits on the keel itself, not on the hull bottom. Versatility and performance, not one against the other.
Why a cutter rig, with both genoa and staysail?
In heavy weather, you furl the genoa and unfurl the staysail without leaving the cockpit. Genoa for 0 to 30 knots, staysail for 30 to 45. Beyond that, you ride out under triple-reefed main or under storm jib. Most of the time, the cutter rig lets you reduce sail at distance, without putting yourself at risk.
Why two engines?
The original MWM still in place (115 hp replacement planned at refit), plus a 60 hp 4-blade outboard on the stern bracket. In the Patagonian channels, against katabatic wind and current, an engine that quits means the boat lying beam-on within thirty seconds. With two engines, you fight back upwind against current, you pull off a shoal, you escape an ice trap less than a metre across. Redundancy turns into useful margin.
Why an oversized tender?
A 2.60 m plastic tender does not survive a 100-knot gust, it flies away like a kite. ARION's tender is 4 m of aluminium, unsinkable, designed like a barge. Built by students at a vocational technical school in Chambéry, deployed and recovered by a derrick on deck. Backup escape route alongside the liferaft, kedging off a shoal, deflecting a bergy bit, ferrying jerrycans: matched to the boat.
1800 Ah of lithium, is that a lot or just enough?
South of 60°S, you draw 250 to 400 Ah a day across Starlink, radar, AIS, autopilot, supplemental heating, fridge, lighting. With 1800 Ah of usable LiFePO4, you hold three days without production in a windless, sunless storm. Beyond that, the diesel genset takes over. The real constraint is not capacity but cold protection: lithium chemistry freezes below 0°C.
How do you stay alive at −25°C inside a boat?
Three layers. Aluminium hull insulated with 80 mm of sprayed polyurethane, anti-condensation lining over the floors, wood interior cladding. 5 kW diesel forced-air heater, dedicated tank, 400 hours of autonomy. Backup heater on kerosene or wood, fully independent of the electrical system. Nobody dies of cold aboard ARION as long as there is fuel left.
Several weeks without a port, what about fresh water?
Watermaker at 60 l/h, 12 V motor, 6 A. We produce more than we consume even on overcast days. Buffer reserve of 600 l in two interior stainless tanks. Consumption 10 to 15 l per person per day: drinking, cooking, minimal hygiene, no shower. If the watermaker fails, the 600 l reserve covers twenty days for two. Beyond that, rationing and rainwater collection.
Is Starlink reliable south of 60°S?
Starlink Ocean covers the entire circumpolar zone via the inclined LEO satellites. Service gaps are more frequent south of southern South America and across some sectors of the South Pacific, but it works. Throughput 25 to 100 Mbit/s, enough for GRIB weather, emails, scientific data. Iridium permanently as backup: if Starlink drops, weather and emergency messages switch over automatically. Two orbits, two operators.
Ice at night, how do you see it coming?
Raymarine Quantum 2 Doppler radar, 24 nautical miles of usable range on large icebergs, 6 to 8 miles on bergy bits 5 to 10 m across. Below that, the radar sees little. Growlers, surface-flush chunks 1 to 3 m, are the real trap: no radar echo, not visible to the naked eye beyond 30 m. At 7 knots, ten to thirty seconds to dodge. Mitigation: reduced speed at night in ice zones (5 to 6 knots), constant visual watch, forward-looking thermal cameras under study.