Logbook – May 20, 2025: Encountering weather systems
Daily Stage: Ajaccio – Bonifacio
- Departure: South entrance of Ajaccio Bay
- Arrival: Bonifacio
- Distance covered: 45 nautical miles
- Navigation time: 7 hours
Weather Forecast vs. Observed: Instability Lurking
On May 20th, we were expecting a trough sliding over the northern Mediterranean, an unstable remnant of a storm front that swept through the PACA region and Haute-Corse. At our departure, weather models predicted a weak south wind at the exit of Ajaccio Bay, turning southwest in mid-morning, then west, strengthening as we approached the Strait of Bonifacio.
Announced Conditions:
- Wind from the south, turning southwest around 10:00 AM, then west towards Bonifacio
- Average force of 10 to 20 knots
- Slightly choppy sea, west waves of about 0.5 m
Observations at Sea:
The scenario generally matched the forecasts. The wind did turn from south to west, with good timing, except for a slight delay in the southwest wind, which only really settled in at 11:30 AM. In the Strait of Bonifacio, the expected strengthening materialized, with optimal conditions on board as the wind and sea came from behind, generating a smooth and gentle ride.
Route Choice and Weather Decisions
The night before, we anchored in Ajaccio Bay at dusk. The area, bordered by rocks and already frequented by other sailboats, required special attention to anchor safely. Once anchored, an anchor alarm was activated to ensure a peaceful night.
At the start, we made the strategic choice to head offshore, rather than follow the coast. The objective: to anticipate the wind’s rotation to the southwest by positioning ourselves at a more favorable angle for the rest of the journey. This gamble slightly lengthens the route… but proves worthwhile: once the flow is established, we benefit from a more efficient trajectory and a good speed towards Bonifacio.
Weather Lesson of the Day
- Know the local effects well: Approaching the Strait of Bonifacio, we were able to confirm the venturi effect well known to sailors. Forecast models indicated a strengthening, and our observation on the water fully validated this local acceleration of the wind.
- Update frequently: Do not be satisfied with a single weather update in the morning. In an unstable and mobile situation, consulting the data several times during the day allows you to refine decisions and anticipate shifts or accelerations of systems.
Life on Board: Between Whale and Offshore Race
At dawn, we had the privilege of seeing a curious pilot whale, come to greet our departure. A rare, calm, and fascinating moment.
Later, a change of atmosphere: we find ourselves in the heart of the Paprec 600 fleet, an offshore crewed race. Our cruising sailboat pales in comparison to the racing machines, but we play along: fine adjustments, discreet benchmarking of the racers’ options, and naturally an attempt to stay in contact.
We observe the tactical positioning: some boats stay offshore to take advantage of the wind shift earlier, others follow the coast. An ideal situation to compare our weather choices in real-time with those of the pros, and learn from their readings of the water.
Motto of the day:
“A well-prepared maneuver is already a maneuver half done.”
(And even more so in the Strait of Bonifacio…)
Tomorrow, heading towards the Lavezzi Islands and Rondinara Bay. Another day full of weather decisions and technical observations in perspective.
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