Safe Speed Rule

Time to apply the safe speed rules

If you think about it conceptually, two vessels in a meeting situation must be able to successfully stop within a hair’s breadth of each other in order to avoid a collision at sea. That, in a nutshell, is the raison d’etre of Rule 6 of the International Rules for Preventing Collisions at Sea (IRPCS), called the safe speed rule. Driving our automobiles on city streets or highways, we gauge our safe speed based on factors like traffic congestion, ice-slicked overpasses, and faulty windshield wipers during a downpour, and always praying the guy we are tailgating doesn’t slam on his brakes.

Rather than wishing or hoping we are doing the right thing when it comes to helming a boat properly to avoid a collision, COLREGS codifies all the information required to operate at a safe speed: Every vessel shall at all times proceed at a safe speed so that she can take proper and effective  action to avoid collision and be stopped within a distance appropriate to the prevailing circumstances and conditions.

Since our judgment can be clouded while driving a boat, (as it is sometimes when we drive our cars; that argument we just had with our spouse, the deadline for the report at work, or that incoming cell phone call), Rule 6 lists the factors we need to pay attention to and take into account each and every time we leave the dock. And to easily remember the important items for determining safe speed and cut through the distractions, we can rely on the following mnemonic or memory tool: Very dry martinis lay Willie down.

Below, on the left, the first letter of each word of the mnemonic is highlighted. That same letter is highlighted on the column on the right, which contains the complete language of the rule:

Very: The state of visibility.
Dry: The traffic density including concentrations of fishing vessels or any other vessels.
Martinis: The maneuverability of the vessel with special reference to stopping distance and turning ability in prevailing conditions.
Lay: At night, the presence of background light such as from shore lights or from back scatter of the vessel’s own lights.
Willie: The state of the wind, sea and current, and the proximity of navigational hazards.
Down: The draft in relation to the available depth of water.

To simplify the mnemonic even further, the rule itself can be reduced into a shorthand version:

Very: State of visibility
Dry: Traffic density
Martinis: Maneuverability of the vessel
Lay: Background light and back scatter
Willie: State of the wind, sea and current
Down: Draft in relation to depth of water

V is not for victory
V is not for victory

The safe speed rule continues with the following factors that must be taken into account by vessels with operational radar, using the assumption that whomever is on watch knows how to operate the equipment correctly:

The characteristics, efficiency and limitations of the radar equipment. Any constraints imposed by the radar range scale in use. The effect on radar detection of the sea state, weather and other sources of interference. The possibility that small vessels, ice and other floating objects may not be detected by radar at an adequate range. The number, location and movement of vessels detected by radar. The more exact assessment of the visibility that may be possible when radar is used to determine the range of vessels or other objects in the vicinity.

These radar factors can be condensed and formed into another mnemonic as follows:

Every: Efficiency and limitations of radar equipment
Radar: Radar range scale
Sees: Sea state and weather
Small: Vessels may not be detected
Motor: Movement of vessels detected
Vessels: More exact assessment of visibility

It is easy to think that the concept of operating at a safe speed is a modern one, based on the advances in hull and propulsion design we have experienced in recent years. In reality, it is not a new issue. A 1905 encyclopedia on U.S. laws noted: Vessels should not proceed at excessive speed in harbors or other places where other vessels are liable to be encountered, particularly in fog.


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