VTS Meteorology and Environmental Factors 2

Question 1

What hydrodynamic phenomenon causes a vessel to sink deeper into the water when transiting shallow channels at speed, reducing available under-keel clearance?

Accepted Answer

Squat

Answer

Squat is a hydrodynamic effect where a vessel moving through shallow water experiences reduced pressure under the hull, causing it to settle lower and potentially reducing under-keel clearance to dangerous levels.

Question 2

A temperature inversion exists over the harbor. How does this atmospheric condition most likely affect VHF radio communications used by VTS?

Accepted Answer

It can cause ducting, extending VHF range well beyond normal line-of-sight limits

Answer

A temperature inversion creates a boundary layer where warmer air overlies cooler air, which can trap and refract VHF radio waves, causing 'ducting' that extends usable range far beyond normal line-of-sight.

Question 3

What is 'significant wave height' as reported in marine weather forecasts provided to VTS operators?

Accepted Answer

The average height of the highest one-third of all waves in a given period

Answer

Significant wave height is the average of the highest one-third of all waves in a measurement period, and it closely corresponds to what a trained mariner would visually estimate as the prevailing wave height.

Question 4

When tidal current through a harbor entrance exceeds 4 knots, what action would a VTS operator typically recommend or require for a large inbound vessel?

Accepted Answer

Delaying vessel transit until the current decreases to a manageable level

Answer

Strong tidal currents severely reduce a vessel's maneuverability and steering response; VTS operators advise delaying transit until the current slackens, as timing a passage around slack water is standard maritime practice.

Question 5

What is a 'storm surge' and why must VTS operators account for it in their traffic management decisions?

Accepted Answer

A wind-driven and low-pressure-induced rise in sea level that affects actual water depths and port flooding risk

Answer

A storm surge is an abnormal rise in sea level caused by strong onshore winds and low atmospheric pressure; it changes actual under-keel clearances, can cause dock flooding, and affects the safety of vessels already moored.

(VTS) Vessel Traffic Services Operator Exam Practice Test

(VTS) Vessel Traffic Services Operator Exam Practice Test

VTS Meteorology and Environmental Factors 2