DWO Chart Work and Pilotage 3

Question 1

What is the primary official source of tidal predictions for US coastal waters?

Accepted Answer

NOAA Tide Tables

Answer

National Weather Service Coastal Bulletins

Answer

US Coast Pilot

Answer

Sailing Directions (Enroute)

Question 2

What is 'slack water' in tidal terminology?

Accepted Answer

The brief period when tidal current velocity is zero between flood and ebb

Answer

The period of maximum tidal current velocity

Answer

The period when water depth is at its minimum

Answer

A condition of no appreciable tidal variation

Question 3

In IALA Region B (Americas), what color marks the port-hand side of a channel when entering from seaward?

Accepted Answer

Green

Answer

Red

Answer

Black

Answer

Yellow

Question 4

What type of buoy is a nun buoy and what does it typically mark in US waters?

Accepted Answer

A conical red buoy marking the starboard side of a channel entering from seaward

Answer

A cylindrical green buoy marking the port side of a channel

Answer

A spherical buoy marking an isolated danger

Answer

A pillar buoy marking a safe water midchannel

Question 5

What is the 'rule of twelfths' used for in tidal calculations?

Accepted Answer

Estimating tidal height at any hour during the tidal cycle

Answer

Calculating tidal current velocities at intermediate times

Answer

Determining the number of tidal cycles per day

Answer

Converting tidal predictions between different chart datums

Question 6

What is the purpose of a 'leading line' (range) in harbor pilotage?

Accepted Answer

To provide an alignment of two objects that guides the vessel along a safe track

Answer

To indicate the maximum safe speed through a channel

Answer

To mark the outer boundary of a traffic separation scheme

Answer

To indicate charted depth at the shallowest point of an approach

Question 7

When approaching a harbor entrance in restricted visibility, what action does COLREGS Rule 19 require above all others?

Accepted Answer

Posting extra lookouts and proceeding at a safe speed

Answer

Anchoring outside the harbor entrance until visibility improves

Answer

Requesting updated weather information from port control

Answer

Switching to hand steering and alerting the engine room