Course to Steer – Theory tips – RYA Day Skipper & Yachtmaster

Passage Planning and Tidal Streams

In our Theory Tips - Tidal Streams we told you how to look up the effect of tides. In this theory tip we are applying it to your proposed journey so we can write our passage plan.

1. Draw the Ground Track (from point A the start point through your destination point B);
(remember: 2 arrows = 2 feet on the ground!)

2. Estimate your boat speed;

3. Measure the distance so you can work out how long it is likely to take;

4. Look up the tide and draw on the Tidal Vector for an hour starting at the same place as our Ground track (from point A to point C);

5. Using your estimated boat speed place your dividers on the end of the Tidal Vector and see where is crosses the Ground Track (at point D);

6. This is known as the Water Track – and you can see what the bearing of the line which is the Course to Steer (do not forget to convert it to a compass heading {see Introduction to Chartwork for more information}).

Note 1: For us to work out our Course To Steer we must drawn a triangle, with each side representing the same length of time.

Note 2: The Course To Steer is the direction you point your yacht when accounting for tide to ensure that you reach your destination.

1. Course
2. Tide
3. Steer

Air Masses – Theory tips – RYA Day Skipper & Yachtmaster

Weather is one of the more difficult areas of sailing theory to understand - the weather patterns we see are mainly due to where the air (known as air masses comes from.

Sources of air masses

The source of air mass depends on where they come from. Warm source regions are:

  • Sahara Dessert (dry and warm)
  • Tropical oceans (moist and warm)

Cold source regions are:

  • Arctic Ocean (moist and cold)
  • Siberia (dry and cold)
  • Northern Canada (dry and cold)
  • Southern Ocean (moist and cold)
A great video from the UK Met Office:

Stability of the air mass

Depending on where the air has come from also controls its stability. Unstable air produces strong winds and rain. Air masses (like polar air) are heated from below which makes them stable, and tropical air is heated from below which makes them unstable.

As air masses move towards us they are modified. As they move over:

  • the sea increases the moisture (as the water evaporates from the surface) - known as a maritime track
  • the land remains relatively dry - known as continental track
  • a warmer surface they cause a colder air mass to become unstable as the surface is warmed from below
  • a colder surface then a warm air mass is cooled from below it becomes stable.

Types of air mass

The combination of the source of the air mass and how it reaches us governs its type.

Tropical Continental

Originating over the Sahara this type of air mass reached the UK most often in the summer months.

Visibility is often moderate or poor due to the sand particles in the air (in the Canaries this type of air mass is known locally as a calima).

Polar Maritime

When the air mass originates from Canada (where it is cold and dry) it is known as Polar Maritime as it has a long passage across the North Atlantic picking up warm air from the sea and becoming unstable with frequent showers often heavy.

Returning Polar Maritime

Returning Polar Maritime is when the passage of the air mass goes further south giving it a longer track south over the North Atlantic (causing the air mass to become unstable as it picks up moisture) before turning north east towards the UK (where the sea track causes it to become more stable).

Arctic maritime

Arctic Maritime is similar to Polar Maritime but has colder and drier air due to the shorter sea track.

Tropical Maritime

Originating from the Caribbean (unstable air), and the crossing the warm waters of the Atlantic on South-Westerly winds, the air becomes stable as it passes over the cooler sea and picks up the moisture. This is the most common type of air for the British Isles.

This type of air mass typically has warm and moist air, with low cloud and drizzle.

Polar Continental

The Polar Continental air mass originates from Siberia (with its cold land mass) in the winter months (in the summer it is known as Tropical Continental as the land mass is warm). The weather produced depends on the sea track: in the south of the UK with the shorter sea track over the English Channel you get clear skies and frosts; when the air mass crosses the North Sea to Scotland and the North of England the air becomes unstable (with rain/snow) due to crossing the longer stretch of water.

Tidal Streams – Theory tips – RYA Day Skipper & Yachtmaster

Under international regulations (Safety of Lives at Sea - SOLAS) all boats have to do a passage plan (sometimes called a voyage plan) before leaving harbour. In tidal waters you need to be able to take account of the effect of the tide on your boat.

What are tidal streams?

Tides are the flow of water around the earth caused by a combination of the earths rotation and the effect on the oceans caused by the gravitational forces formed between the sun, moon and earth. This horizontal movement is called the tidal current, or tidal stream.

The largest movement (and hence the strongest tidal streams) usually is at the times of high and low water.

The shape of the land also affects the speed of the tidal stream (it's faster in tidal estuaries and narrow straits). The highest tide in the world is the Bay of Fundy in Canada - and its here you get the fastest tidal streams.

The weakest tidal streams are known as slack tides.

Where can I find the tidal stream data

Information on the tides that are flowing can be found in a Tidal Stream Atlas such as the English Channel Tidal Stream Atlas which is available at the RYA shop.

The tidal atlas gives you a pictorial representation of the tidal flow. You select the correct page for the tidal hour at the port listed at the top of the page, then select the arrow closest to where you will be. The direction of the arrow shows the direction of tidal flow, and the two numbers represent the speed of the tide (for example 09.14). The smaller number is for neaps and the larger number is for springs. This doesn't mean 14 knots for a spring tide in our example - they do not print the decimal point so its 0.9 knots for neaps and 1.4 knots for springs.

Another source of tidal information is from tidal diamonds. These are shown as magenta diamonds on the chart with a letter inside.

With tidal diamonds you again need to work out the tidal hour in relation to the nominated port. Each tidal diamond has data listed for direction of flow (dir) in degree, and then two columns for springs (Sp) and Neaps (Np).

If its not exactly springs or neaps you can take a figure in between for mid range for both tidal streams or tidal diamonds. If it doesn't line up with springs, neaps or mid range then you have to do "computation of rates". Details of how to do this will be in a future Theory Tip.

Coriolis Effect – Theory tips – RYA Day Skipper & Yachtmaster –

Weather is one of the more difficult areas of sailing theory to understand - and one of the reasons is due to the earth's rotation!n

What is the Coriolis Effect?

The earth rotates in an anti-clockwise direction on its axis. This rotation causes the winds to deflect to the right in the northern hemisphere and to the left in the southern hemisphere. This is what causes wind to rotate around low and high pressure systems in opposite directions if you are north or south of the equator!nn

This effect is named after Gustave-Gaspard de Coriolis who worked out why in 1835.nnn

How does the Coriolis Effect affect me?

If you stand in the centre of a spinning playground roundabout (spinning anticlockwise) and attempt to throw a ball it appears to curve to the right. Anyone who is not on the roundabout and watching will see the ball travelling in a straight line. Have a look at our video to see why.

What happens to the winds?

Winds in the northern hemisphere appear very much like a ball thrown on a children's roundabout - they are deflected to the right and are a major factor in explaining why winds blow anticlockwise around low pressure and clockwise around high pressure in the northern hemisphere and visa versa in the southern hemisphere. nnIf it wasn't for the Coriolis Effect the wind would flow directly from high pressure areas to low pressure areas.

The Coriolis Effect influences global wind patterns - and also gives the UK the prevailing south-westerlies, and the Canary Islands the north-easterlies.nn

Clouds – Theory tips – RYA Day Skipper & Yachtmaster

Weather is one of the more difficult areas of sailing theory to understand - and remembering the names of cloud types is one of the most tricky areas.

What are clouds?

Clouds are produced through condensation. The air rises, cools - and with the reducing temperature the air can hold less water vapour so condensation occurs. The condensation makes tiny drops (each m3 of air contains 100,000,000 droplets) of water or ice crystals which settle on dust particles - which form the droplets. Whether the droplets are ice or water depends on the height (and the temperature) of the cloud.

The water droplets (or ice crystals) then start sticking together - forming the clouds. Clouds are made up of either water droplets or ice droplets depending on the height and air temperature.

Great video from the UK Met Office

High clouds – cirrus / cirro

These are clouds over 6000m high. They include:

Medium height clouds – alto

The clouds that are between 2000m and 6000m are medium height are include:

Also at this level are Nimbostratus which are rain bearing layered clouds.

Low level clouds

These clouds are below 2000m and include:.

Coastal Skipper / Yachtmaster Theory: Course content

What’s covered in my RYA Coastal Skipper / Yachtmaster Theory course?

This course is designed for those people who are going on to do the Coastal Skipper Course Completion Practical certificate for both sail and motor. The theory is the same standard as that required for the MCA Yachtmaster Coastal and Yachtmaster Offshore Certificate of Competence (CoC).

The contents of the RYA Coastal Skipper / Yachtmaster Theory course are listed in the RYA Yachtmaster Scheme Syllabus and Log Book (G158)

The course can be taken either in our classroom or on-line. Upon successful completion you will be awarded the RYA Coastal Skipper / Yachtmaster Shorebased Certificate and be ready to move on to the RYA Day Skipper Practical course.

The contents of the course includes:


  • Dead reckoning
  • Satellite Derived position
  • Use of waypoints to fix position
  • RADAR fixes
  • Techniques of visual fixing
  • Fixes using a mixture of position lines
  • Relative accuracy of different methods of position fixing
  • Areas of uncertainty

The Magnetic Compass

  • Allowance for variation
  • Change of variation with time and position
  • Causes of deviation
  • Compass checks for deviation, but not correction
  • Allowance for deviation
  • Different types of compass


  • Causes of tides - springs or neaps
  • Tide tables - sources
  • Tidal levels and datum
  • Standard and secondary ports
  • Tidal anomalies (Solent etc)

Tidal streams

  • Sources of tidal information
  • Tidal stream information in sailing directions and yachtsmen's almanacs
  • Tide rips, overfalls and races
  • Tidal observation buoys, beacons etc


  • IALA system buoyage in Regions A and B
  • Limitations of buoys as navigational aids


  • Harbour regulations and control signals
  • Methods of pre-planning
  • Clearing lines
  • Use of soundings
  • Transits and leading lines


  • Characteristics
  • Ranges - visual, luminous and nominal
  • Rising and dipping distances
  • Light lists

GNSS and Chart Plotters

  • Principles of operation and limitations of use
  • Raster and vector charts
  • Datum
  • The importance of secondary means of position fixing via an independent source and keeping a separate record of position
  • The importance of paper charts

Echo sounders

  • Principles of operation and limitations of use

Logs (speed and distance measuring)

  • Principles of operation and limitations of use

Deck log

  • The importance of the log as a yachts official document
  • Layout of log, hourly and occasional entries

Rules of the Road

  • A sound knowledge of the International Regulations for Preventing Collisions at Sea (IRPCS) except Annexes 1 & 3


  • Basic terms, the beaufort scale
  • Air masses
  • Cloud types
  • Weather patterns associated with pressure and frontal systems
  • Sources of weather forecasts
  • Ability to interpret a shipping forecast, weather fax, and weather satellite information
  • Land and sea breezes
  • Sea fog
  • Use of a barometer as a forecasting aid

Safety at sea

  • Personal safety, use of lifejackets, safety harnesses and lifelines
  • Fire prevention and fire fighting
  • Coastguard and boat safety scheme
  • Preparation for heavy weather
  • Life rafts and helicopter rescue
  • Understanding the cap[abilities of vessel and basic knowledge of stability

Navigation in restricted visibility

  • Precautions to be taken in fog
  • Limitations to safe navigation imposed by fog
  • Navigational strategy in poor visibility

Passage planning

  • Preparation of charts and notebook for route planning
  • Customs regulations as they apply to yachts
  • Routine for navigating in coastal waters
  • Strategy for course laying
  • Use of, and visual confirmation of, waypoints and routes
  • Use of weather forecast information for passage planning strategy
  • Sources of local and national regulations

Marine environment

  • The responsibility to minimise pollution and protect the marine environment

Details on more RYA courses

If you would like to view the contents of other courses please look at our RYA course contents page