Mixed Deck — All RYA YACHTMASTER Topics Flashcards

What is a 'through-hull fitting' and why are they a critical safety consideration?

Answer: A pipe or valve passing through the hull below the waterline — if one fails, it can cause rapid flooding; all crew should know their locations and how to close or plug them

Through-hull fittings (seacocks, transducers, engine cooling inlets) penetrate the hull below the waterline. A failed fitting can cause rapid, dangerous flooding. All should have functioning seacocks and be accessible with emergency bungs nearby.

When planning an offshore passage, how should the 'watch system' be organised?

Answer: A rotation system ensuring adequate rest for all crew, with watches typically 3-4 hours, a designated skipper on call, and clear handover procedures

The watch system must ensure every crew member gets adequate rest while maintaining a proper lookout at all times. Typically, watches are 3-4 hours (shorter at night), with a clear handover briefing on course, weather, and traffic.

What is the purpose of a 'jackstay' or 'safety line' on an offshore yacht?

Answer: A strong webbing or wire running the length of the deck to which crew clip their safety harness tethers, allowing movement fore and aft while remaining attached to the vessel

Jackstays are strong webbing straps or wires running along each side of the deck. Crew clip their harness tethers to the jackstay, allowing them to move along the deck while remaining securely attached to the yacht.

What does the term 'fetch' mean in relation to wave generation?

Answer: The uninterrupted distance of open water over which the wind blows, directly affecting wave height

Fetch is the uninterrupted distance of open water over which the wind has blown. The longer the fetch, the greater the wave height. Offshore areas with long fetches (e.g., Atlantic approaches) can produce very large seas.

In basic celestial navigation, the 'assumed position' (AP) is:

Answer: A convenient whole-degree Lat/Long position near the DR position, chosen to simplify the sight reduction calculation

An AP near the DR position is chosen with whole-degree values to minimise the complexity of sight reduction tables (e.g., HO 249 or NP 303). The intercept is then plotted from the AP.

What role does the 'pilot book' play in offshore passage planning?

Answer: It provides detailed descriptions of coastlines, harbours, approaches, dangers, anchorages, and local conditions that supplement chart information

Pilot books (sailing directions) provide detailed written descriptions of coastlines, harbours, approaches, recommended tracks, dangers, tidal information, facilities, and local knowledge that supplements the information shown on charts.

What is the difference between a 'water track' and a 'ground track' in coastal navigation?

Answer: Water track is the vessel's movement through the water; ground track is the actual path over the seabed, accounting for tidal stream

Water track is determined by heading and speed through water. Ground track (or track made good) is the actual path over the ground, which is the vector sum of water track and tidal stream.

How does the Coriolis effect influence wind patterns in the Northern Hemisphere?

Answer: It deflects wind to the right of its path, causing wind to blow parallel to isobars rather than directly from high to low pressure

The Coriolis effect, caused by the Earth's rotation, deflects moving air to the right in the Northern Hemisphere. This causes wind to flow roughly parallel to isobars, creating the characteristic anticlockwise circulation around lows.

What is a 'vessel constrained by her draught' (CBD) and what lights does she display?

Answer: A power-driven vessel deeply loaded and severely restricted in ability to deviate from the course being followed — displays three all-round red lights in a vertical line in addition to normal lights

A CBD vessel is a power-driven vessel so deeply loaded that its draught severely restricts its ability to deviate from its course. It displays three all-round red lights in a vertical line plus its normal power-driven vessel lights.

For a cross-Channel passage, which Met Office forecast service provides the most detail for skipper-level planning?

Answer: Inshore Waters Forecast combined with the 5-day shipping forecast text and synoptic chart — plus GRIB files for wind modelling

Skilled passage planning uses multiple sources: Inshore Waters Forecast (detailed coastal), Shipping Forecast (overview), synoptic charts, and GRIB numerical model data for wind and wave forecasts.

A depth sounding taken with an echo sounder shows 18.5 m. The tide height is 2.3 m. What is the charted depth at that position?

Answer: 16.2 m

Charted depth = sounding − tide height = 18.5 − 2.3 = 16.2 m. Subtracting the tide height removes the tidal contribution and gives the depth referenced to chart datum.

Why does tidal range vary between springs and neaps on a fortnightly cycle?

Answer: The relative positions of the Sun, Earth, and Moon — at new and full Moon, solar and lunar tidal forces combine (springs); at quarter Moon they partially cancel (neaps)

Spring tides occur when the Sun and Moon are aligned (new/full Moon), adding their gravitational effects. At first/third quarter the Sun and Moon are at right angles, partially cancelling each other, producing neaps.

What lights does a vessel 'not under command' display at night?

Answer: Two all-round red lights in a vertical line, plus sidelights and stern light if making way

A vessel not under command (NUC) displays two all-round red lights in a vertical line. If making way through the water, she must also display sidelights and a stern light, but no masthead light.

What medical supplies should be carried on an offshore passage beyond coastal first aid?

Answer: A comprehensive medical kit including prescription medications (antibiotics, strong painkillers, anti-seasickness), wound closure strips, splints, burns dressings, and a medical reference book

Offshore passages may be days from medical facilities. The kit should include prescription medications (arranged through a ship's medical scheme), comprehensive wound care, splints, burns treatments, and a medical reference such as the Ship Captain's Medical Guide.

A vessel needs to cross a bar with 1.8 m draft plus 0.5 m clearance. The charted depth at the bar is 0.4 m. The current tide height is 1.5 m. Can the vessel cross?

Answer: No — required depth = 2.3 m; available depth = 0.4 + 1.5 = 1.9 m — 0.4 m short

Required = draft + clearance = 2.3 m. Available = charted depth + tide height = 0.4 + 1.5 = 1.9 m. Shortfall = 0.4 m. The vessel cannot safely cross at this state of tide.

When using the Yachtmaster method to estimate arrival time at a tidal gate, which tidal atlas pages are used?

Answer: Pages referenced to hours before and after HW at the tidal atlas standard port for that area

UK tidal atlases have 13 pages: 6 hours before HW, HW, 6 hours after HW at a named standard port. The skipper must calculate HW time at that standard port to use the correct page.

Approaching a harbour entrance at night, a single white light is seen dead ahead. This could indicate:

Answer: Any of the above and the source should be verified before proceeding

A single white light ahead could be an anchor light, a safe water buoy, or a vessel's stern light, so its source must be positively identified before proceeding.

When planning a Channel crossing, why is it important to account for Traffic Separation Schemes (TSS)?

Answer: TSS in the Dover Strait and other areas carry legal obligations for crossing vessels, including crossing at right angles and not impeding vessels in the traffic lanes

The TSS in the English Channel (particularly Dover Strait) is one of the busiest shipping lanes in the world. Crossing vessels must comply with Rule 10 of COLREGs: cross at right angles, do not impede lane traffic, and allow extra time for the crossing.

Why is it important to identify 'ports of refuge' during offshore passage planning?

Answer: To have predetermined alternatives available if weather deteriorates, crew become ill, or mechanical problems arise, including approach information and entry requirements

Ports of refuge are pre-planned alternative destinations along the route where the vessel can seek shelter. For each, the navigator should have approach information, tidal data, entry requirements, and berthing options ready.

What is a 'Secondary port difference' in tide tables and how is it applied?

Answer: A time and height correction listed in tables that, when applied to a standard port's prediction, gives the secondary port's tide

Secondary port differences include time differences (HW and LW) and height differences (HW and LW heights). These are applied to the standard port predictions after interpolating for the appropriate date.