Rule 19 — Conduct in Restricted Visibility

Rule 19 applies to vessels not in sight of one another in restricted visibility. The normal in-sight stand-on/give-way rules (Rules 12–18) do not apply when the vessels cannot see each other — every vessel must take its own avoiding action.

If radar alone detects another vessel forward of your beam, avoid altering course to port unless you are overtaking that vessel. Avoid altering course towards a vessel abeam or abaft the beam. If a fog signal is apparently forward of the beam, or a close-quarters situation cannot be avoided, reduce to the minimum speed at which you can keep course, take all way off if necessary, and navigate with extreme caution.