This method of signalling involves the waving of a pair of flags in various positions, each representing a letter of the alphabet (shown below). Semaphore flags provide a simple method of secure, short range, ship-to-ship communications.

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A shipping chart (or British Admiralty (BA) chart in the UK ) is effectively a nautical equivalent of an OS map. It is made up of numerous colours, has lots of symbols, and is covered in lines and numbers.

Once you understand these basic elements it is possible to do some simple chart work. For more advanced chart work and navigation you also need indepth knowledge of other resources such as tide tables, tidal streams, variation and deviation.

A general chart layout is shown below:

The YELLOW areas are DRY LAND

The GREEN areas are Parts which Dry at low water

The DARK BLUE and LIGHT BLUE areas are Always Covered by Water

The WHITE areas are CLEAR (navigable) WATER

Just like an OS map, a shipping chart has a whole host of symbols attached to it. By understanding these, one gains a greater understanding of what it is the shipping chart is trying to portray.

Since there are too many symbols to remember, the admiralty chart of symbols 5011 lists them in booklet form.

Some of the common symbols are shown below:

	Example of an Easterly cardinal buoy, showing the essential features of a buoyage symbol.
	Port Hand Marker. Can be cones or posts.
	Starboard hand marker. Can be cones or posts.
	Example of a marker post. In this case a special mark.
	A wreck
	Tidal diamond
	A rock which is awash at low water
	A drying rock
	A major light. Includes information on light characteristic, height and range. (E.g. Q. 8m 17M )
	Anchorage
	Radar Tower
	Church spire or tower

As mentioned previously, shipping charts are covered in lines and numbers. These are common to all charts and mean different things.

Scale

The chart scale is basically how detailed the map is:

Large scales are used for harbours and approaches
Medium scales are used for coastlines
Small scales are used for sections of open sea

The scale can be seen around the edge of the chart where the distance is given in nautical miles

(1 nautical mile = 1.15 miles)

Compass rose

True and magnetic compass roses can be found at various places on a chart. These are used in conjunction with a parallel rule to obtain directions in degrees true or degrees magnetic.

They also allow conversion between the two different standards.

Lattitude and Longitude

The horizontal and vertical lines marked on charts are lines of latitude and longitude respectively. They provide a type of grid reference system for measuring a vessels position.

They can also be used as the reference point from which directions are measured.

Latitude and Longitude is measured in degrees and minutes (e.g. 056^o 40'N).

1' = 1 minute of latitude = 1 nautical mile

1^o = 60 minutes of latitude = 60 nautical miles (NM)

Latitude is read off from the sides of the chart and longitude from the top and bottom.

Tidal streams

Information on tidal streams can be found in a panel at the side of the chart. This information relates to 'tidal diamonds' drawn on the chart.

The tidal diamond gives the speed and direction of a tidal stream at that point.

Chart datum

Chart datum is the level from which all water depths and drying heights are measured. This height is determined by the hydrographical office as the lowest predicted astronomical tide.

Contour lines are drawn which join areas of the same depth (like an OS map) at 2, 5 and 10m. These are shaded blue.

Variation

As mentioned earlier, the bearings measured in true and magnetic vary. This difference is known as variation and differs according to location. Hence the compass roses give the correct amount of variation for the year of publication.

Variation is measured in degrees easterly or westerly.

Any bearing measured from a vessel will be in degrees magnetic. They must be converted to degrees true before continuing.

When the variation is WESTERLY you SUBTRACT the variation

When the variation is EASTERLY you ADD the variation

Deviation

A mariners compass should point to magnetic north but in reality is affected by the boats own magnetic field. This magnetic field exists due to the presence of metal used in the boats construction.

The amount of deviation varies on different headings
[It may also be easterly or westerly]

Before using a compass, the amount of deviation must be known. For a small boat this can be achieved by sailing along a transit (whose bearing is known) on 8 different headings.

The result is a list of recorded and known bearings. The difference between them can be used to draw a deviation card.

The effects of tides and tidal streams must be considered when planning a route and plotting a course.

• Tides affect the height of the water at a given point at a given time and can prevent entry to a port or harbour if the low water level is less than the draught of your vessel.
• Tidal streams are the movement of water around the UK and can aid or impede ones progress. A strong tidal current can easily set a small boat off course.

   

Therefore, when planning a route it is important to consult tide tables and tidal atlases.

As mentioned previously the rate and direction of a tidal stream is given on the chart. This information relates the speed and direction of the tide at various points on the chart to the time of high water at a particular given port.

I.e. All tidal stream information is related to a reference port (known as a standard port) at the time of high water.

To find out the speed and direction of the tide at any time , at any point , you first need to determine the time of high water for the standard port on that day. This is achieved through the use of tide tables.

Tide tables

Tide tables give the height of the water above chart datum at a particular time of day for that day of the year. It is essentially a curved plot which indicates the rate of the tide with horizontal graduations for the time and vertical gradients for the height.

As well as these, the plot includes mean low water and mean high water marks.

The time of high tide occurs at the peak of the plot (approximately mid-way along the x-axis). Reading off the height at this point gives the depth at high tide.

Twelfth's rule of thumb

If you are in a situation where only a rough estimate of the tide is needed you can use a method known as the twelfth's rule of thumb.

It assumes the tides rise and fall proportionally with time and that the time between low water and high water is 6 hours. It also assumes that in the first hour after high or low water the tide rises or falls by 1/12 th its range; in the second hour 2/12 th its range; in the third hour 3/12 th ; in the fourth hour 3/12 th ; in the fifth hour 2/12 th and in the sixth hour 1/12 th .

Now that the time of high water for the standard port has been determined, the speed and direction of a tidal stream at a particular time is found by turning to the page with the closest time. This usually covers a larger area.

The above diagram represents a much simplified tidal stream map for the Irish Sea.

More specific information can be determined by using the same time to look up the reference to the required tidal diamond on the chart.

The number of lights a vessel carries and the way in which these lights are displayed allows you to identify a vessel at night. They can also be used to indicate the activities the vessel is engaged in.

silhouette	type of vessel
	Power driven vessel under 50m
	Sailing vessel (not under power). More common to use a tri-colour.
	Vessel at anchor- 50m or above
	Vessel Pushing ahead
	Vessel pushing ahead (stern view)
	Vessel constrained by draft- under 50m
	Towing astern- tow less than 200m
	Fishing vessel- under 50m
	Vessel restricted in ability to manoeuvre. Not making way.
	Vessel towing astern- tow less than 200m.Restricted in ability to manoeuvre.
	Vessel not under command, not making way
	Pilot Vessel
	Submarine- making way
	Hover craft (minimum displacement)
	Vessel engaged in trawl fishing

It can be seen from above that some vessels will look very similar even though they may be doing completely different things. Also, how do you tell if a vessel is underway, at anchor, or restricted in some way?

Looking more closely at the masthead and stern lights will give you a clue:

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masthead lights

light sequence	meaning	ditty
	Vessel not under command. (e.g. engine or steering failure)	Red over Red. This boat is dead
	Indicates a sailing boat. [not commonly used]	Red over Green. Sailing machine
	A Fishing Boat	Red over White. Fishing tonight
	A Trawler	Green over White. Trawling tonight
	A tug with a tow under 200m	White over White. A short tow in sight
	A tug with a tow over 200m	White over White Over White. A long tow in sight
	A vessel constrained by her draft	Red over Red over Red. Rudder rubbing rocks
	A pilot boat	White over Red. Pilot ahead
	A vessel restricted in its ability to manoeuvre. (e.g. survey vessels, dredgers, dive boats, tugs, aircraft carriers).	Red over White over Red. Red when restricted
	Minimum displacement

stern lights

light sequence	meaning	ditty
	Stern lights of a tug pushing a barge.	Yellow over Yellow. A pushy inland fellow
	Stern lights of a tug towing astern.	Yellow over White. My towline is tight

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The Sailing Dinghy

There are many different classes of sailing dinghy, each with their own pieces of rigging and canvas. The diagram below shows the basic parts of a typical sailing dinghy.

 

 

Parts of a sail

 

 

Points of Sailing

This refers to the course on which you are sailing with respect to the direction of the wind.

When sailing on different points, the boat and sails have to be trimmed accordingly to achieve best performance. The basic areas which need attention are:

• sail trim
• boat trim
• boat balance
• centre/ dagger board position
• course steered

These are commonly known as the five essentials.

 

 

 

Sailing terminology

With sailing comes a whole load of terminology including (but not limited to) the parts of the boat itself, the direction you are sailing, the crew commands as well as the general speak.

Some of the common terms are shown below to get you started:

 

Apparent Wind - the direction of the wind as is relative to the speed and direction of the boat

Backstay - a support wire that runs from the top of the mast to the stern

Battens - thin, stiff strips of plastic or wood, placed in pockets in the leech of a sail, to assist in keeping its form

Beam reach - a point of sail where the boat is sailing at a right angle to the wind

Bolt Rope - a rope sewn into the luff of a sail for use in attaching to the standing rigging

Boom - the horizontal spar which the foot of a sail is attached to

Bowspirt - a spar extending forward from the bow

Broach - to spin out of control, either causing or nearly causing a capsize.

Broad reach - a point of sail where the boat is sailing away from the wind, but not directly downwind

By the Lee - sailing with the wind coming from behind, and slightly to the side, that the sails are on

Capsize - to turn a boat over

Centerboard - a fin shaped, often removable, board that extends from the bottom of the boat as a keel

Cleat - a fitting used to secure a line to

Clew - the lower aft corner of a sail

Close hauled - a point of sail where the boat is sailing as close to the wind as possible

Close reach - a point of sail where the boat is sailing towards the wind but is not close hauled

Downhaul - a line, attached to the tack, that adjusts tension in the sail

Drift - the leeway, or movement of the boat, when not under power, or when being pushed sideways while under power

Foot - the bottom part of a sail

Foremast - the forward mast of a boat with more that one mast

Foresail - the jib

Forestay - a wire support line from the mast to the bow

Furl - to fold or roll a sail and secure it to its main support

Genoa - a large foresail that overlaps the mainsail

Gooseneck - a device that connects the boom to the mast

Halyard - the line used to raise and lower the sail

Head - top of the sail

Head to Wind - the bow turned into the wind, sails luffing

Headsail - a sail forward of the mast, a foresail

Heave To - to stop a boat and maintain position (with some leeway) by balancing rudder and sail to prevent forward movement, a boat stopped this way is "hove to"

Helm - the tiller or wheel, and surrounding area

Helmsman - the member of the crew responsible for steering

Heel - the leeward lean of the boat caused by the winds action on the sails

Hike - leaning out over the side of the boat to balance it

Hoist - to raise aloft

In Irons - having turned onto the wind or lost the wind, stuck and unable to make headway

Jib - a foresail, a triangle shaped sail forward of the mast

Jibe - a change of tack while going downwind

Kicking Strap - a line that adjusts downward tension on the boom

Leech - the back edge of a sail

Lee Ho - the command given to inform the crew that the helm is being turned quickly to leeward, turning the boat windward

Leeward - downwind

List - the leaning of a boat to the side because of excess weight on that side

Luff - the front edge of a sail, and the flapping in the wind of the front of the sail (luffing)

Mainsheet - the line that controls the boom

Mizzen - the shorter mast behind the main mast on a ketch or yawl

Outhaul - the line that adjust tension along the foot of the sail along the boom

Painter - a line tied to the bow of a small boat for the purpose of securing it to a dock or to the shore

Port tack - sailing with the wind coming from the port side, with the boom on the starboard side

Reach - sailing with a beam wind

Ready about - prepare to come about

Reef - to reduce the size of a sail

Rigging - the standing rigging is the mast and support lines, running rigging is the lines with which you adjust the sails

Running - a point of sail, going directly downwind

Sheet - a line used to control the sail

Shrouds - support wires for the mast

Spinnaker - a large, light sail used in downwind sailing

Spreaders - struts used to hold the shrouds away from the mast

Starboard tack - a course with the wind coming from starboard and the boom on the port side

Tack - the front, lower corner of the sail, also course with the wind coming from the side of the boat, also to change course by turning into the wind so that the wind comes from the other side of the boat

Tiller - controls the rudder and is used for steering

Topping lift - a line that holds up the boom when it is not being used, also the line that controls the height of a spinnaker pole

Traveler - a device that the mainsheet may be attached to which allows its position to be adjusted

Trim - to adjust the sails, also the position of the sails

Windward - upwind

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Knots

Bowline A very useful knot that can be tied and loosened quickly, yet holds fast. Used to make loops to drop over pilings, secure sheets to sails or line to buckets. Carrick Bend An excellent and secure knot. Very useful when  joining heavy lines. Clove Hitch Most often used to temporarily secure a line to a piling. Easy to tie and holds well to a round post. Figure Eight A simple stopper knot. Easy to tie and untie even after being under strain. Half Hitch A quick knot to tie, its holding power can be increased by wrapping an extra turn of line around the item its being tied to. Reef Knot The most convenient line to tie two lines together when there is tension on both of them. Sheep Shank A way of shortening a line. Holds as long as tension exists on the line. Can be secured by inserting toggles short pieces of wood) in the loops. Sheet Bend & Double Sheet Bend A general utility knot for joining two lines together. Easy to untie and holds fast.