BOAT-COMPARATOR Guide
Crossing Shipping Lanes (TSS) on a Rental Boat: the Rule and the Method
Ushant, Gibraltar, the Bonifacio strait: how a traffic separation scheme works, what COLREG Rule 10 says, and how to cross the cargo ships’ route safely.
A container ship doing 18 knots covers a mile in three minutes and can neither stop nor swerve easily. To channel that traffic, the world’s busiest waters are organised into traffic separation schemes (TSS) — one-way “motorways of the sea” that leisure boats must know how to cross cleanly.
Where do renters meet one?
Rarely on a day trip, sometimes on a cruise: the Ushant TSS off the Iroise sea, the Strait of Gibraltar scheme off Sotogrande and Tarifa, the Dover Strait, the Bonifacio strait between Corsica and Sardinia, or the approaches to major ports (Marseille-Fos, Genoa, Piraeus). Even without a formal TSS, the ferry corridors between mainlands and islands — Toulon-Corsica, Piraeus-Cyclades, Split and its islands — concentrate heavy traffic that calls for the same reflexes.
COLREG Rule 10, in plain words
The international collision regulations devote Rule 10 to traffic separation schemes. For a rental boat, three obligations: do not impede vessels following the lanes — a 12-metre sailboat has no right of way to claim there; cross with your heading at right angles to the lane axis — the heading, not the track: you do not correct for drift, which keeps your intention readable on the ships’ radar; and do not linger in the central separation zone. The usual right-of-way rules come after this principle: in a shipping lane, the more manoeuvrable vessel keeps clear, and that is you.
The method for crossing
Prepare: cross where the scheme is narrowest, engine ready even under sail, crew briefed. Watch: a constant bearing means collision course; the boat’s AIS or an app gives each ship’s name, speed and crossing point. Listen: keep a VHF watch on channel 16 and on the local traffic-control channel. Cross decisively: perpendicular heading, sustained speed, no zigzagging. At night, revise the navigation lights before committing. Squire’s reference study of the Dover Strait scheme, published in 2003 in the Journal of Navigation, shows dangerous encounters disproportionately involve vessels cutting across the lanes: crossing, not transiting, is the critical manoeuvre (see the study on Google Scholar).
What it changes for your rental
Contracts define a sailing area: check it includes the crossing you plan, and that your declared experience matches the programme — some owners ask for a sailing CV for island passages. In a flotilla or with a skipper, the question disappears: one more good reason to be accompanied for a first crossing. And to find a boat fit for open water, a Boat-Comparator search shows each offer’s design category and equipment.
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