Rule 18 — Responsibilities Between Vessels

Except where Rules 9, 10 and 13 otherwise require, a power-driven vessel underway keeps out of the way of a vessel not under command (NUC), a vessel restricted in ability to manoeuvre (RAM), a vessel engaged in fishing and a sailing vessel. A sailing vessel underway keeps out of the way of NUC, RAM and fishing vessels; a vessel engaged in fishing, so far as possible, keeps out of the way of NUC and RAM.

The status must be real and signalled. 'Engaged in fishing' means fishing with gear that restricts manoeuvrability, not a person angling with trolling lines that do not. RAM arises from the nature of the vessel's work restricting manoeuvre; size or inconvenience alone is not enough. A sailing vessel using propelling machinery is power-driven and by day displays a cone apex down where it can best be seen.

A vessel constrained by her draught may, in addition to normal power-driven signals, exhibit three all-round red lights or a cylinder and must navigate with particular caution. Other vessels should, if circumstances admit, avoid impeding her safe passage. That wording is not the same as an absolute stand-on privilege, and vessels still comply with the other applicable collision rules when risk develops.