Meteorology & Seamanship Flashcards

What is the 'lee shore' danger and why does it affect seamanship decisions?

Answer: A lee shore is land downwind of the vessel — being driven towards it is dangerous as the wind and sea set the vessel onto the coast

A lee shore is land on the leeward (downwind) side of the vessel. Being near a lee shore is dangerous because wind and sea are pushing the vessel towards the coast. If mechanical or sail power fails, the vessel may be driven ashore.

What is 'heaving to' and when is this seamanship technique used?

Answer: A technique for slowing a vessel almost to a stop while maintaining control, used in heavy weather to reduce strain and wait for conditions to improve

Heaving to involves adjusting sails and rudder (on a sailing vessel) or engine and helm to bring the vessel almost to rest in a controlled manner, making it relatively comfortable in heavy weather while waiting for conditions to improve or to handle an emergency.

What is the purpose of a 'drogue' or 'sea anchor' in heavy weather?

Answer: To slow the vessel and keep the bow or stern towards the waves, reducing the risk of broaching or being pooped

A drogue is deployed astern to slow the vessel and prevent it from surfing dangerously on wave faces. A sea anchor is deployed from the bow to keep the bow into the waves, reducing drift and the risk of lying broadside (beam-on) to breaking seas.

What is the significance of 'Shipping Forecast areas' around the UK?

Answer: They are named sea areas for which the BBC and Met Office broadcast weather forecasts including wind, sea state, visibility, and pressure

The Shipping Forecast divides UK and NW European waters into named sea areas (Forties, Cromarty, Forth, etc.) for which forecast wind direction and force, precipitation, visibility, and pressure trend are broadcast four times daily on BBC Radio 4 LW.

What is a 'tropical revolving storm' (TRS) and what are the warning signs of its approach?

Answer: An intense low pressure system in tropical latitudes with circular winds exceeding 64 knots — preceded by a long, low swell and falling pressure

A Tropical Revolving Storm (hurricane, typhoon, or cyclone) is an intense tropical low with sustained winds above 64 knots. Warning signs include abnormally long oceanic swell from an unusual direction, rapid pressure fall, backing winds, and increasing cirrus cloud.

What does 'ISOBAR' mean and how are isobars used on weather charts?

Answer: Lines connecting points of equal atmospheric pressure — closely spaced isobars indicate strong winds; widely spaced indicate light winds

Isobars are lines on a synoptic chart connecting points of equal atmospheric pressure, measured in millibars (mb) or hectopascals (hPa). The spacing of isobars indicates the pressure gradient force — closely-spaced isobars produce strong winds.