BOAT-COMPARATOR Guide
Reading the marine forecast before your rental: wind, sea, and when to walk away
Knots, Beaufort, wind sea and swell, gusts: marine-weather basics for deciding with open eyes — and the honest thresholds for giving up.
The marine forecast is not the beach forecast: bright sunshine can hide 25 knots of mistral. Ten minutes of reading the night before turn a doubtful day into a successful one — or a wisely postponed one.
The three numbers that matter
Mean wind (in knots: under 10, lovely; 10-15, pleasant; 15-20, sporty in a small boat; beyond, a serious conversation). Gusts: 12 knots gusting 25 is worse than a steady 15. The sea: half a metre of chop shakes a 6-metre boat; long swell is easier than short, crossed sea.
Where to look
The coastal bulletins from the national forecaster (the operators' reference), and fine-mesh visual models (AROME on apps like Windy) to see the exact hour the thermal breeze arrives. Mediterranean rule: morning is almost always calmer — the thermal fills in between 11 am and 2 pm.
The honest walk-away thresholds
License-free or small open boat: beyond 12-15 established knots, the day loses its point. In a 7 m+ RIB: 20 knots is manageable, but fragile passengers pay. A near-gale warning: it is a no, and serious operators cancel of their own accord — their weather policy (rebook/refund) is a listed selection criterion.
The classic trap
Leaving on flat calm without checking the trend: the mistral 'arriving at 2 pm' turns the ride home into a washing machine. Check the wind's arrival time, not just its strength — and always keep an hour's margin on the return time.