Restricted visibility

Fog, mist, snow, heavy rain and similar causes can restrict visibility under Rule 3(l). Rule 19(a) concerns vessels not in sight while navigating in or near such an area. It requires neither every target to be invisible in all directions nor merely nighttime. The framework includes visual condition between the vessels and visibility context. MCA MGN 369 Amendment 1 distinguishes this scope from Section II without creating a universal speed or CPA figure. A radar target’s plotted geometry does not independently turn the encounter into Rule 15 crossing.

Rule 19(b) requires safe speed adapted to circumstances and conditions, with power-driven vessels’ engines ready for immediate manoeuvre. Paragraph (c) preserves due regard to those conditions when complying with Section I. Lookout, available means, radar limitations and systematic appraisal continue under Rules 5–7. Application does not consist of replacing everything with “always turn starboard”. Rule 19 does not assign Section II stand-on and give-way roles: both vessels have duties within its own framework. Readiness, speed and observation therefore belong to one continuing appraisal.