Safe speed

Rule 6

Proceed at a speed that allows proper and effective action to avoid collision and lets the vessel be stopped within an appropriate distance.

Relevant factors include:

visibility

traffic density

vessel maneuverability

stopping distance and turning ability

background lighting at night

wind, sea and current

navigational hazards

vessel draft in relation to available depth

radar characteristics and limitations when radar is fitted

There is no universal number of knots that constitutes safe speed.