Core Nautical Knowledge Flashcards

A VTS operator observes two power-driven vessels, Vessel A and Vessel B, on a collision course in open water. Vessel A is on Vessel B's port bow, meaning Vessel B has Vessel A on its own starboard side. Neither vessel is constrained in any way. According to the International Regulations for Preventing Collisions at Sea (COLREGs), which vessel is the 'give-way' vessel?

Answer: Vessel B is the 'give-way' vessel and should take early and substantial action to keep well clear.

This is a classic crossing situation under COLREGs Rule 15. The vessel which has the other on her own starboard side shall keep out of the way. In this scenario, Vessel B sees Vessel A on its starboard side, making Vessel B the give-way vessel. Rule 16 requires the give-way vessel to take early and substantial action to keep well clear.

When navigating in an IALA Region A buoyage system, a VTS operator advises a vessel to pass to the north of a hazard. Which cardinal mark would the vessel be expected to see marking this hazard?

Answer: A black and yellow pillar buoy with two cones pointing upwards.

A North Cardinal mark indicates that safe water lies to the north of the mark. To pass to the north of a hazard, a vessel must pass north of the North Cardinal mark. A North Cardinal is identified by its black-over-yellow color scheme and its topmark of two black cones pointing upwards.

In the context of a vessel's turning circle, what is the term used to describe the distance gained in the direction of the original course from the point where the rudder is first applied until the vessel has altered course by 90 degrees?

Answer: Advance

'Advance' is the correct nautical term for the distance a vessel moves along its original course from the moment the rudder is put over until its heading has changed by 90 degrees. 'Transfer' is the distance gained at right angles to the original course. 'Tactical Diameter' is the distance gained at right angles to the original course after turning 180 degrees.

A VTS operator is monitoring a deep-draft vessel and needs to ensure it stays clear of a known underwater obstruction. On the electronic chart display, the operator sees a symbol with the letters 'Wk' next to it. What does this symbol represent?

Answer: A wreck, where any associated number indicates the cleared water depth above it at chart datum.

The abbreviation 'Wk' on nautical charts universally stands for a wreck. An associated number indicates the surveyed depth of the water over the wreck at the level of chart datum. This is critical information for a VTS operator to ensure vessels with sufficient draft do not pass over it.

A VTS operator observes a vessel on the radar that is steering a course of 090°T at a speed of 10 knots. However, the vessel's ground track (Course Over Ground) displayed by the system is 105°T, and its Speed Over Ground is 11 knots. What navigational phenomenon best explains this difference?

Answer: A strong current setting in a southeasterly direction.

The difference between a vessel's course and speed through the water (heading) and its course and speed over the ground is caused by the movement of the water itself (current/tidal stream). The vessel is being pushed to the right (from 090° to 105°) and sped up, which is consistent with a current that has both a southerly and easterly component.

A VTS operator is monitoring a vessel that has reported a main engine failure and is drifting towards a sensitive marine area. Which of the following actions, if available to the vessel's master, represents a critical last-resort measure to arrest the vessel's drift?

Answer: Deploying the vessel's anchors.

While making radio calls, displaying signals, and requesting assistance are all vital actions, the most direct physical action the vessel can take to stop its movement and prevent grounding or entering a restricted area is to deploy its anchors. This is a fundamental seamanship action for arresting a vessel's uncontrolled movement.