Know the Rules All masters must be aware of the International Regulations for Preventing Collisions at Sea. A summary of these rules is given in this section. Safe speed All vessels must travel at a safe speed at all times. A safe speed cannot be expressed as a maximum or minimum number of knots because it varies with circumstances and conditions. The master (skipper) must continually assess the safety of the vessel's speed. A safe speed is one at which the vessel can be stopped in time to avoid any danger which arises suddenly. In judging a safe speed the master must consider a number of issues including: Visibility -- drive slowly in rain, fog, mist, smoke or glare. Special caution is required at night because many potential hazards may not be lit or may not be easily seen. Background shore lighting may confuse you. Other vessels -- slow down on busy waterways and when near moored or anchored vessels, working vessels showing special signals and large vessels which have difficulties in manoeuvring. Navigation hazards -- slow down in shallow areas or in unfamiliar waterways. Water depth can vary and change frequently. Not all hazards may be marked or lit and signs, buoys, marks or lights may have shifted or been vandalised. Wind, waves and currents -- may adversely affect the manoeuvrability of a vessel. Manoeuvrability of the vessel -- stopping and turning ability depends on the speed travelled, wind and current and the boat's design (such as hull shape,