BOAT-COMPARATOR Guide
Renting a boat on the Atlantic: tides and coefficients, painlessly
Tidal range, coefficients, currents, high-water time: what the tide changes for a rental in La Rochelle, Brittany or Arcachon.
The Mediterranean sailor who rents in La Rochelle or the Morbihan discovers a new parameter: the sea rises and falls by several metres, twice a day. Nothing complicated — but it needs anticipating.
The useful vocabulary
High water and low water alternate roughly every 6 hours. The coefficient (20-120) states the amplitude: at 100 — 'spring tide' — the water moves a lot and currents strengthen; at 45, all is gentle. The range (the height difference) reaches 5-6 metres in Brittany — hence sill harbours and anchorages that dry out.
What it changes in practice
Timing: some harbours and channels (Arcachon first) are only workable around high water — the operator sets your window on it; respect it on the way back. Currents: in the narrows (Morbihan!), pass at slack or with the flow. Anchoring: dropping in 2 metres at high water on coefficient 90 means sitting on the sand three hours later — count the depth at LOW water.
The tools
The harbour tide tables (posted everywhere, apps too), and one simple rule: ask the operator 'what time must I be back, and where must I not go at low water?' — those two answers summarise the day.
The Atlantic bonus
The tide animates the scenery: banks emerging, channels drawing themselves, shellfish gathering at low water. A constraint? More like a show with a fixed timetable.
Free checklist
Rent a boat with no nasty surprises
Deposit, insurance, check-in inspection, fuel, navigation areas, weather: our checklist covers everything to verify before booking and on departure day. Sign up to access it and receive our tips by email.
Thank you! Your checklist is ready: Rent a boat with no nasty surprises →