Mixed Deck — All RYA DAY SKIPPER Topics Flashcards

What does 'leeway' mean for a sailing yacht?

Answer: The sideways drift of a sailing vessel caused by wind pushing the hull to leeward

Leeway is the angular difference between the direction the boat is pointing (heading) and the direction it is actually moving through the water (course made good through water), caused by the wind's sideways force.

When planning a coastal passage, why is it important to identify 'bolt holes' along the route?

Answer: To identify alternative ports of refuge in case weather deteriorates or an emergency occurs

Bolt holes are alternative harbours or sheltered anchorages along the passage route where the vessel can seek refuge if weather conditions deteriorate, equipment fails, or crew become ill.

What lights must a power-driven vessel of less than 50m show when underway at night?

Answer: Masthead light, sidelights and sternlight

A power-driven vessel under 50m requires one forward masthead light (225°), red and green sidelights (112.5° each), and a white sternlight (135°).

The Rule of Twelfths is used to estimate the rise or fall of the tide. In the 3rd hour of a 6-hour tide cycle, what fraction of the range rises?

Answer: 3/12 of the range

The Rule of Twelfths: hour 1 = 1/12, hour 2 = 2/12, hour 3 = 3/12, hour 4 = 3/12, hour 5 = 2/12, hour 6 = 1/12. The 3rd hour contributes the largest share.

On a chart, a blue circle with 'PA' next to a depth sounding means:

Answer: Position Approximate — the sounding position is not precise

PA stands for Position Approximate, indicating that the sounding or feature has been placed on the chart with limited positional accuracy.

At a secondary port, the time difference on HW is listed as −0h 15min. Standard port HW is 1200. What is the secondary port HW time?

Answer: 1145

Secondary port HW = 1200 − 15 minutes = 1145. The negative sign means the secondary port HW occurs before the standard port HW.

What is the 'range' of a tide?

Answer: The vertical difference between high water and low water

Tidal range is the vertical difference in height between consecutive high water and low water. Spring tides have a larger range than neap tides.

In a pilotage plan, the term 'mark abeam' refers to:

Answer: The moment a charted feature is directly to the side of the vessel (90° to heading), used as a timing or turn trigger

A mark abeam is used in pilotage to trigger a course alteration or confirm position — when the mark is directly to port or starboard, it confirms you have reached a precise position line.

What does 'drying height' on a chart indicate?

Answer: The height of the seabed above chart datum — these areas are exposed (dry) at low water

A drying height (shown underlined on charts) indicates how far the seabed rises above chart datum. These areas are covered at high water but exposed at low water.

What is the purpose of a 'clearing bearing' in pilotage?

Answer: A compass bearing that, when maintained, keeps the vessel clear of a specified hazard

A clearing bearing (also called a danger bearing) is a pre-planned compass bearing that defines the outer boundary of a danger. Keeping the bearing greater or lesser than this value keeps the vessel safe.

What type of cloud is most associated with an approaching cold front?

Answer: Cumulonimbus with heavy showers and possible thunderstorms

Cold fronts are characterised by a narrow band of cumulonimbus clouds producing heavy rain, possible thunderstorms, and squally winds, followed by clearer conditions with cumulus clouds.

What causes spring tides?

Answer: The gravitational pull of the sun and moon acting in alignment (at new and full moon)

Spring tides occur when the sun and moon are in alignment (syzygy), at new moon and full moon. Their combined gravitational pull produces the highest high tides and lowest low tides.

On an Admiralty chart, a depth sounding shown in bold italic figures indicates:

Answer: A drying height — the figure is the height above chart datum when dry

Bold italic soundings on a chart are drying heights — areas that dry out at low water. The figure gives the height above chart datum (CD) at which the feature dries.

What does a 'leading line' or 'transit' provide for a navigator?

Answer: A line of position confirmed by aligning two charted objects, providing a reliable bearing

A transit (or leading line) is formed when two charted objects are in line. This provides a very accurate line of position and is often used for entering harbours safely.

Under COLREGs Rule 18, in which order of priority must vessels keep out of the way of other vessels?

Answer: Power-driven vessels give way to sailing vessels, fishing vessels, and vessels constrained by draught, in that order

Rule 18 establishes a hierarchy: power-driven vessels yield to sailing vessels, vessels fishing (gear out), vessels not under command (NUC), and vessels restricted in ability to manoeuvre (RAM) and constrained by draught (CBD). Smaller sailing vessels also give way to large ships restricted in channels.

What is the purpose of a 'course to steer' calculation?

Answer: To find the compass heading that will result in the vessel making good the desired track over the ground, allowing for tide and leeway

A course to steer calculation determines the compass heading to counteract the effects of tidal stream and leeway, ensuring the vessel follows the intended ground track.

A MOB (man overboard) situation occurs. The first crew member to spot the casualty should:

Answer: Maintain constant visual watch on the casualty, point continuously, and shout 'man overboard'

Maintaining sight of the casualty is the first priority — once lost in the water, finding them again is extremely difficult. Other crew deal with the manoeuvre and equipment deployment.

The tidal range at springs is 5.0 m and at neaps is 2.0 m. The range today is 3.5 m. What does this suggest?

Answer: The tide is between neaps and springs, closer to springs

3.5 m is midway between 2.0 and 5.0, but slightly closer to springs (halfway = 3.5 m exactly). This represents a mid-range tidal coefficient.

What is the first action to take if you discover a fire below decks on a yacht?

Answer: Alert the crew, close hatches and ventilation to starve the fire of oxygen, and use the appropriate extinguisher

The first actions are to alert the crew, close hatches and ventilation to reduce oxygen supply, and then fight the fire with the appropriate extinguisher. Opening hatches would feed the fire with air.

What is meant by 'chart datum' (CD) on UK Admiralty charts?

Answer: Approximately the level of the Lowest Astronomical Tide (LAT)

Chart datum on UK Admiralty charts is set at approximately LAT (Lowest Astronomical Tide) — the lowest level the sea is predicted to reach under average meteorological conditions.