The outboard motor is a spark ignition engine. Fuel from the fuel tank enters the carburetor where it mixes with air in a given proportion. From the carburetor, the gas mixture enters the cylinder. In the cylinder, a spark plug emits a spark that ignites the mixture, triggering an explosion that drives the piston. This sets in motion a crankshaft (or drive shaft) linked to the piston by a connecting rod. Successive explosions in the cylinder cause the crankshaft to turn and a gear assembly activates the propeller.
The internal temperature of a spark ignition engine is over 3200 Celsius (4000 F). Therefore, the motor must be cooled. Outboard motors are cooled by water.
While the motor is running, water is drawn in through openings located at the base of the motor (see Figure 2.1, no. 14) under the anti-cavitation plate. Water flows around the cylinders before being flushed out into the surrounding body of water through a cooling system control jet. It exits through an orifice located near the cylinder head (see Figure 2.1, no. 1).
Most outboard motors are two-stroke engines; four-stroke engines also exist.
Two- and four-stroke engines differ in the way that lubricating oil enters the cylinders. In a two- stroke engine, oil is added to fuel in the tank itself (manufacturers specify how much oil to add to the fuel). However, some two-stroke outboard engines have two tanks: one for gas and another for oil. The oil and gas mix automatically before reaching the cylinders. In a four- stroke engine, oil is added through a separate opening located near the drive shaft. Too little oil can cause the metal to overheat and damage the motor.
Trouble-Shooting and Maintenance
The engine’s operating instructions usually provide information and advice on trouble-shooting, minor repairs and maintenance.
To prevent breakdowns, boaters should make a habit of staying alert to signs of motor wear and tear. Similarly, it is advisable to keep spare parts in the tool box and learn to perform basic repairs.
Follow these safety rules when performing repairs:
The repair kit should be air-tight and contain:
Motor won’t start
Motor starts but not easily
Motor running in fits and starts
Propeller not turning
Motor suddenly stops
As a boat operator you should know that the “recommended gross load capacity” that can be safely carried in the hull concerned:
The capacity plate also indicates the “recommended safe limits of engine power” for the hull concerned. This calculation is based on the recommended gross load capacity.
Motor Boat Operations
When mixed with air, gasoline evaporates quickly. Therefore, use caution when fueling a boat. Because gasoline fumes are heavier than air, they can accumulate in the hold, i.e., in the bottom of the boat. The following procedure is used for fueling:
The fuel tank should be kept away from sparks and heat and stowed in a well-ventilated location. Always store fuel in a clearly marked fuel container. Fuel tanks are red or orange for safety reasons. Other colours must not be used.
Motor Installation and Adjustments
Before installing the motor, ensure that the fastening clamps (see figure 2.1, no. 8) are open to maximum and that the motor is attached to a safety rope or chain. If the boat is in shallow water, tilt the motor to prevent the propeller from scraping the bottom. At the dock, ensure that the boat is properly moored; however, mooring lines must provide enough slack to allow for the effects of added weight. Place the motor on the dock with the top section toward the boat. Check again that the clamps are open. Using the handles, lift the motor and set it in place on the stern plate; tighten the clamps and fasten the rope or chain to the boat.
Loading the Boat
Load displacement and water movement in the hold are two factors that affect the boat’s stability. Therefore, the load must be secured (tied down) near the hold with ropes, and the hold kept dry. After securing the load, also check the trim of the boat.
Adjusting the Trim
An outboard motor boat is operated and maneuvered as if the hull were moving parallel to the water. Passengers and materials must be placed to evenly distribute the load along the length and width of the boat.
Poor: Too much weight in front
Poor: Too much weight in back
Correct: Load is evenly distributed and ensures optimal performance
One common mistake is to overload an outboard boat. The recommended load capacity is shown on the Capacity Plate issued by the Department of Transport. Never exceed the specified load.
Steering System Tension
The tension of the steering system is adjusted at its pivot point by a screw or bolt called a copilot. It must be tightened just enough to prevent the boat from changing direction when the operator takes his/her hand off the throttle bar. The tilt of the motor (see Figure 2.1, no. 9) must be adjusted so that the drive shaft is at a right angle to the surface of the water when the motor is running at full speed. If the motor leans too far out, the stern of the boat will sink and the bow will tend to tap the water. On the other hand, the bow will tend to plough the water if the motor is tilted too far in. Trials on the water will show the best tilt in relation to the load.
Motor too close to waterline; vessel will nose dive.
Motor too far from waterline; vessel will tend to tap surface.
Motor is at a right angle to the water surface; operation should be smooth if the vessel was properly loaded.
This important device is found on most outboard motors and serves to hold the motor upright against the transom. Since the clamp keeps the motor in the water when the boat is in reverse, it should normally be engaged. As a general rule, the clamp automatically disengages if the motor strikes an underwater object.
Starting the motor
The operator must sit to the right of outboard motors that have a steering bar connected directly to the motor.
To change the direction of an outboard boat you must change the position of the motor’s propeller.
If the bar is pulled to the right, the bow of the boat will turn left, and if the bar is pulled to the left, the bow of the boat will turn right.
With practice, boat operators will soon learn to act quickly and correctly.
When maneuvering in reverse, the lift lock mechanism must be engaged to prevent the motor from tipping. Obstacles must be avoided with great care since the motor is no longer protected from collision.
Reversing is much more complicated than forward maneuvering, and therefore requires extra alertness.
Leaving the Dock
Occupants must enter the boat when the front and rear mooring lines are still fastened to the dock. One person steadies the vessel while the others board by stepping into the bottom of the boat and keeping their bodies as low as possible.
Follow the reverse procedure to get out of a boat.
To leave a dock in a motor boat demands some forethought. If other boats are nearby, the throttle bar (gas control handle) can be moved in the direction of the dock and the boat backed out in reverse. If the wind is blowing from the dock, greater force is required to clear the dock and avoid colliding with other boats.
The boat pulls away from the dock in reverse (throttle bar turned toward the dock). Once the boat is fully clear, it can head out in Forward provided the way is unobstructed.
To land a boat, approach the dock at a 30-45 degree angle. Once near the dock, move the throttle bar toward the dock to clear the bow of the boat and take up a parallel position. Nearer the dock, move the bar to the other side, slow the throttle and for a instant the boat will back up, bringing the stern close to the dock. Once alongside the dock, moor the boat. If the wind is blowing toward the dock, it is best to approach from a wider angle. If the wind is blowing from the dock, approach at a narrower angle.
Launching from Shore
In fair weather, launching a boat from shore is relatively easy. With the motor raised, the boat is lifted and pushed into the water, front first. Once the boat is afloat, with the stern barely touching the shore, hold it at a 90-degree angle to the shore in order to board, first in the centre, and then at the bow. Lastly, the driver shoves the boat out into the water, walking alongside in the water, and boards at the stern. When launching, the person in the centre nudges the boat out into the water with an oar until the water is deep enough to start the motor. This person can also guide the boat in the desired direction. Then, after starting the motor, shift to Forward, gaining speed as the boat moves farther from shore.
Landing on Shore
To land on shore in fair weather, stop the motor where the water is still fairly deep and tilt it out of the water to prevent damaging the propeller. It is important for the driver to instinctively know the location of the stop mechanism and the tilting lever. To lighten the front end, any passengers in the bow of the boat will move to the centre and row to shore. On reaching the shore, one person sets foot on the ground and holds the boat steady while the other passengers step out. Once the boat is empty, it can be lifted and carried to the shore for mooring. Avoid pushing the boat ashore.
In poor weather, it is best to approach the shore backwards. This will prevent water from accumulating in the boat. With the motor running, turn the boat so that the stern is toward shore. The centre passenger holds this course with the oar. Then, stop the motor and tilt it out of the water. The waves will carry the boat to shore. To prevent the stern from dipping into the trough of the waves as they strike the bow, the rower pulls gently on the oars.
Accelerating and Planing
Acceleration tends to make a boat leave the water and hydroplane on the surface; this movement is triggered by the wash of the motor. It lifts the boat by several degrees. This seriously diminishes the operator’s visibility in front of the boat and makes it more difficult to effectively use the motor’s propulsion force. To correct this situation, simply accelerate slightly to pass over the wave and regain a relatively horizontal trim.
Operating in Waves
In poor weather, to reduce the risk of capsizing or taking on water, waves must be crossed bow first. With a motor, the boat’s speed can be quickly adjusted to synchronize its forward motion with the movement of the waves. In this way, the bow crosses the waves more easily.
Certain rules of thumb can improve towing efficiency:
Sometimes, towing is the worst option. The first role of the rescuer is to save lives and reduce human suffering. When boating conditions prevent towing, specialized towing companies can be called in for assistance. The same applies when the boat will not stand up to towing (see manufacturer’s recommended limits) or was not designed for towing (such as inflatable crafts).
To make the towed boat easier to maneuver, fasten the hitch fairly close to the waterline at the centre of the bow. Some boats have lugs or hooks for fastening a hitch.
In poor weather, the length of the tow line depends on the waves. To avoid collision, synchronize the speed of the two boats and their movement over the crest or trough of the waves.
It is extremely important that both vessels are cresting the waves at the same time. The length of towing rope should be adjusted to ensure that the vessels are properly spaced.
Towing is more effective if the traction point is located in the rear centre of the towing boat. This is done simply if a ring or lug is installed at the centre of the stern. Otherwise, a V-shaped rope assembly can prevent sideways traction on the towing boat. A hitch attached to a V-assembly can slide from side to side.
The towing speed depends on the boat type, weight and means of propulsion. It must be adjusted to keep the towed boat steady. Where a motor boat is used, avoid placing excessive strain on the motor.
If possible, the hitch should be easy to cast off. The knots used in a hitch must be able to withstand considerable and variable strain. The bowline knot is the most commonly used. round turn knot and two half hitches can be used for towing light loads. However, never use a square knot or a clove hitch for towing.
Responding to Breakdowns
Know the following actions to take in response to breakdowns on board a boat:
Operating a boat safely demands that operators develop alertness, judgment, caution and foresight.
Caution and foresight
Port: If a power-driven vessel approaches within this sector, maintain with caution, your course and speed.
Starboard: If any vessel approaches within this sector,
keep out of its way.
(Note: This rule may not always apply if one or both vessels are sailboats.)
Stern: If any vessel approaches this sector, maintain with caution, your course and speed.
Boat operation is subject to a series of rules similar to those governing road traffic. The Collision Regulations and the Criminal Code of Canada are two valuable sources of information for anyone interested in more details on the regulations governing the operation of a vessel. The following are a few of the many rules they set down.
Rules of the Road
The rules of the road in navigation are often similar to the rules on land. The Collision Regulations contain many rules pertaining to navigation; however, four rules are basic to navigation.
A boat that is overtaking another must steer clear of the overtaken vessel’s path.
A vessel approaching from the port side must give way. (A) keeps clear of and must avoid crossing ahead of (B).
When two vessels are heading toward each other, each must reroute and pass to the right of the other. (A) blows one blast and alters course to starboard, (B) blows one blast and alters course to starboard.
As a general rule, rowboats, sailing vessels and canoes have the right-of-way over power- driven boats. However, if one vessel is unable to maneuver as it normally would, the most maneuverable vessel gives way.
Responsibility for avoiding collisions is shared by everyone using the waterway. Common sense must be used along with alertness and caution.
The concept of taking early and substantial action must be applied in all cases.
Anyone operating a vessel be constantly on the alert, both in sight and sound.
Operating a vessel requires the operator’s sustained attention; operators must be constantly alert and watchful to everything around them. Not only must they take account of what is happening in front, behind and on both sides of them, like a road vehicle driver, but they must also pay attention to what is under them. A single glance at the sky is enough to see the early signs of bad weather, or perceive impending dangers (electrical wires or others).
The water surface can also conceal dangers: tree trunks, water plants, rocks near the surface, etc. For that reason, they required deep concentration when operating a boat. This alertness allows the operator to adjust speed to boating conditions, and thereby enhance the safety of the operator and of others.
The Effect of Waves
One of the rules governing the operation of a vessel is that “every vessel is responsible for the effects of its wake.” Boat operators must therefore ensure that the wake of their vessel does not endanger nearby pleasure boaters or cause property damage to their vessels.
Boaters coming to help must not compound the circumstances of an accident or, for that matter, cause another one. The effect of the boat’s wake is extremely important when approaching the victim. Steps must be taken to ensure the wake is not so high that it washes over the victim.
Boat operators must know that they cannot interfere with marine signals;
Know that the operator of a pleasure sailing craft, that has the wind on the port side, shall take early and substantial action to keep well clear of other sailing vessels..
Know that the operator of a pleasure sailing craft, that has the wind on the same side and is to windward of other sailing vessels, shall take early and substantial action to keep well clear of sailing vessels which are to leeward..
Know that the operator of a pleasure sailing craft, that has the wind on the port side and cannot determine with certainty whether other sailing vessels to windward have the wind on the port or on the starboard side, shall take early and substantial action to keep well clear of the sailing vessels.
Know that the operator of a pleasure craft shall take early and substantial action to keep well clear of vessels being overtaken.
The International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA)
During the IALA conference in November 1980 two navigation marking systems, ie the System A (red colour for the left hand of the ship) and the System B (red colour for the right hand of the ship), were combined into one - the IALA System.
In the IALA System the regional (of the systems A and B) principle of painting of the lateral signs was maintained. The countries that accepted the red colour for the left hand lateral sings were included in the region A. The countries that use the green colour for the left hand lateral signs were included in the region B. In the both regions, the fairway direction is the one leading from the sea (when a different manner is used than an adequate notice is provided).
Following to the division into the IALA System regions, marine maps contain respective notice, ie the "IALA System Region A" or the "IALA System Region B".
The IALA System has five types of signs that are used in various associations. The signs have specific identification elements that make them easily recognizable to the sailors. The lateral signs in the Regions A and B are different, but the other four signs are common for these both regions.
The lateral buoys and marks are placed according to the direction accepted for marking of the right and left side of the fairway. In the Region A, during the day and night, the green colour is used to mark the right side of the fairway, and the red colour - to mark the left side. In the Region B the colours are reversed, ie the red colour is used for the right side, and the green colour - for the left side. See below.
Region A Region B
When the path is divided on a fairway, then the direction of the main path is shown with a modified lateral buoy in order to indicate the direction of this main path.
Modified Lateral Buoys and Marks for the Region A Modified Lateral Buoys and Marks for the Region B
Cardinal Buoys indicate that the deepest water occurs at the side of the mark's name. They are placed to the north, south, east or west from the hazard. The cardinal buoys have mainly the shape of columns or poles. They are painted in horizontal, yellow and black stripes, and their topmarks (two cones) are painted black. The arrangement of cones at the top is an indication of the black stripe (or stripes) position on the buoy.
Cones with tops up: the black stripe is above the yellow one. Cones with tops down: the black stripe is under the yellow one.
Cones bases towards one another: Cones tops towards one another:
The black stripes above and below yellow. Yellow stripes above and below black.
Cardinal buoys are equipped with white light characterised by a special rhythm. The main types of rhythms are as follows: flashing (Q) or fast flashing (VQ). The flashing light has 60 or 50 flashes per minute. The fast flashing light has 120 or 100 flashings per minute.
The lights in individual quadrants have the following characteristics:
The number of flashes - 3, 6 and 9, in the respective quadrants E, S and W facilitates the identification of the cardinal buoys, as the number can be associated with the positions of the 3, 6 and 9 hours on the clock dial. A longer flash (not less than 2 seconds) just after the VQ (6) or Q (6) is typical of the S quadrant. There are two other marks with white light, however, their rhythm is very different and cannot be confused with the rhythm of the white light used in the cardinal buoys.
Marks indicating Isolated dangers are placed directly over minor obstacles around which the water is navigable. The have shapes of columns, poles or other, however, they are difficult to confuse with the cardinal buoys. They are black with horizontal red stripes. The topmarks consists of two black spheres one above the other. The light is white - a group flash light Fl(2) with two flashes in a group.
Marks indicating Safe water. They indicate that water is navigable around the mark and they do not show any hazards. They can be used to mark, eg a fairway axis or as approach signs. The safe water marks appearance is completely different from the one of the buoys that indicate the hazard. Their may have a shape of a sphere, a column or a pole, with a red sphere as a topmark. These are the only marks painted in vertical stripes (red and white). When the light is installed, then its colour is white and its rhythm may be isophase, occulting, long flash or the Morse Code letter "A".
Special Buoys and Marks do not represent navigational aids. They indicate a special area or an object mentioned on maps or in other nautical documents and publications.
These special marks are painted yellow and have a topmark in the shape of a yellow lying cross (X). The light (if installed) is also yellow. As in poor visibility it is possible to mistake the yellow colour for the white, the yellow lights of the special marks cannot have the rhythm adopted for marks with the white light. The shape of the special marks cannot be confused with the shape of navigational marks, ie if special marks have been used to mark, eg the left side of the fairway, then they must have a cylindrical and not conical shape. The special marks may have letters or numbers painted on them.
New hazard attention is being drawn to the fact that a "new danger" that has not yet been announced in nautical documents may be indicated with a duplicating mark being identical (in all details) with the principal mark. The duplicating mark should stay until the news about the new danger has been adequately announced. The "new danger" mark should be equipped with a Racon sending out the letter "D" in the Morse Code.
This information can be found at http://www.nauticalissues.com/en/iala.html
Navigation Day Shapes
Here are just a few
Application Indication Restriction
Vessel Under Sail & Power
Cone > 12m
Ball > 7m (not in channel) > 20m (in anchorage)
3 Balls (vert. line) > 12m
Not Under Command
2 Balls (vert. line) > 12m
Restricted in Ability
1 Ball+1 Diamond+1 Ball > 12m (except dive boats)
2 Cones (vert. line) > 20m (but must display (nets or trawling) basket shape
Vessel Towing or Vessel Being Towed
Diamond Tow > 200m
Here are just a few
Vessels under way or making way
From theInternational Regulations for Preventing Collisions at Sea
Aft Forward Starboard Aft Forward Startboard
Rule #25 Rule #23
Power Vessel Towing Vessel < 50m (tow < 200m)
1. Power Vessel, > 50m in length 1. Towing Vessel > 50m in length with tow < 200m
2. Power Vessel, < 50m (displaying the optional second masthead light) 2. Towing Vessel < 50m (may have second masthead light)
Aft Forward Starboard Aft Forward Startboard
Rule#23 Rule #24 or #23 (a)(ii)
1. Towing Vessel > 50m in length with tow > 200m
2. Towing Vessel < 50m in length (may have second masthead light)
with tow > 200m
Aft Forward Starboard Aft Forward Startboard
Rule #24 or #23 (a)(ii) Rule#24
The nautical chart is a 2-dimensional representation of a 3-dimensional world. And although this results in various distortions, as long as two requirements are met we can use this image for navigational purposes.
1. The angles between three objects in the chart should be the same as the angles between the real objects which they represent.
2. A straight course should appear as a straight line in the chart.
To fulfil these demands a nautical chart requires parallels and meridians that are both straight and parallel. Moreover, the meridians will need to be perpendicular to the parallels.
A well known method to create such a chart is called the Mercator projection after Gerard “Mercator” Kremer, a Flemish scholar who studied in 's Hertogenbosch (the Netherlands) and Leuven (now Belgium) and who invented his famous projection in 1569. The Mercator chart was designed for sailors and can be constructed by wrapping a cylinder around the planet so that it touches the equator. On this cylinder the surface of the earth is projected and finally the cylinder is cut open to yield the 2-dimensional chart.
But where the meridians converge on the globe they run parallel in the projection (see chart below), indicating the distortion. Look, for example, at a high parallel. The length of such a parallel on the globe is much smaller than the equator. Yet, on the chart they have exactly the same length creating a distortion which gets bigger nearer to the poles. The figure below shows the construction of the Mercator projection. From this it is clear that only the vertical scales should be used for measuring distances.
The vertical scale depicted on the right demonstrates the distortion. The two little navy coloured markers have precisely the same size, the upper one measures only 0.64 degrees (= 38.4 nm) while the other measures 1.00 degrees (= 60 nm). So, distances (in degrees or in miles and minutes) should not only be read on the vertical scale, but also at approximately the same height.
The horizontal scale is only valid for one latitude in the chart and can therefore only be used for the coordinates (a point, but not a line). If you divide the surface of the earth in eight pieces, and lift one out and project it, you end up with the figure below. The result is that both A-A' and B-B' are now as long as the bottom of the chart and are “too long”.
But there are of course other projections in use by sailors. An important one is the Stereographic projection, which is constructed by projecting on a flat plane instead of a cylinder. On this chart parallels appear as slightly curved and also the meridians converge at high latitudes. So, strictly speaking, a straight course will not appear as a straight line in the chart, but the parallels remain perpendicular to the meridians. Most often, distortions are scarcely noticed when this projection is used to chart a small area. Like the Mercator projection, the vertical scale represents a meridian and should be used for measuring distances.
Another projection is the Gnomeric projection on which the meridians are again converging. But most importantly, the parallels are arcs of a circle while great circles appear as straight lines. On a sphere the shortest route between A and B is not a straight line but an arc (part of a great circle). Though this is also true when you – for example – cross a little bay, we use for simplification a loxodrome (a handy straight line on your Mercator chart which does not reflect your shortest route). On a Gnomeric chart this same loxodrome is an arc, while your shortest route (a great circle) ends up as a straight line. Hence, the gnomeric projection is particularly useful when sailing great circles (like when you dabble in circumnavigation) and is beyond the scope of a coastal navigation course.
Organisation of the chart
Information in the chart
Coordinates and positions
A pair of nautical dividers (single handed dividers) is used to obtain precise coordinates from the chart. This device enables you to take the distance between that particular position and the closest grid line. You then place the dividers on the scale with one end on this grid line, leaving the other end precisely at your coordinate. Do this twice to get both latitude and longitude at the scale on the edge of the chart.
Below are some examples.
32° 06,3' N , 25° 07,3' E
32° 04,4' N , 24° 54,7' E
31° 46,0' N , 25° 04,0' E
31° 48,4' N , 25° 25,0' E
32° 01,0' N , 24° 57,8' E
32° 14,2' N , 25° 29,6' E
31° 54,9' N , 24° 54,8' E
31° 54,8' N , 25° 10,0' E
31° 52,0' N , 24° 44,3' E
Some chart symbols come with a little line and circle indicating the precise location, like the “Radio mast”, otherwise the center of the symbol is the precise location.
Another possible notation of 33° 28,5' E is 33° 28′ 30" E, which however doesn't easily allow for more precision like 33° 28,500' E does. Also note that in most countries a comma - and not a dot - is used as the decimal separator. So instead of 33° 28.500' E, the consensus notation for mariners is 33° 28,500' E.
To measure the distance between, for instance, these two oil rigs, we will again need our dividers. Remember, we can only use the vertical scale.
We first take a convenient distance like 10' (10 nautical miles) on the vertical scale using the middle latitude. Then we start walking with the dividers from the southern oil rig to northern one. Finally, we adjust the dividers to measure the small remaining part at its own height, i.e. its own latitude.
The image shows that the total distance is 37 nautical miles.
So, now we can measure distances and both plot and read out positions, but we also need directions. For example we need to find the course from safe-water buoy A to safe-water buoy B. To accomplish this we may use parallel rules as shown in this chart below:
Navigation dividers are designed to be used one handed (you may need the other to hold on to your chart table!), and to be opened with the points crossed. Do not be frightened of pressing the points in to the chart, this will help you to hold them steady and to measure distances more accurately, just do not press them in so hard you damage the chart.
Also if you are practicing at home place a protective surface between the chart and your varnished dining room table!
Breton plotter - also known as a Portland Course Plotter. They are essentially the same thing. A rectangular ruler with a rotating compass rose fixed in the center. They are used for plotting and measuring directions on nautical charts.
If you are familiar with the use of parallel rules, a Douglass Protractor or two set squares for plotting bearings by all means continue to to so, there are many different ways of working on charts and they all have their place.Because it was what I first learnt with, I used parallel rules until I came across a plotter was used, I soon realised how much faster it was.
Bretton or Portland plotter Parallel rule, dividers and compass Nautical slide rule
A roller ruler is a useful tool and for small boats is more compact and a lot cheaper than a parallel rule but if used carefully is just as good.
To determine the direction between two positions or points on a chart, line up the rulers with the two points and then step the rulers to the nearest compass rose.
Once you have the edge of the ruler in the center of the compass rose, you can read the direction. Make sure you read the direction on the side of the compass rose in your intended direction of travel. In this case, to travel from the southern-most buoy to the northern-most buoy, set your course to 045° True. However, to travel from the northern-most buoy to the southern buoy, you would set your course to 225° True.
Conversely, to plot a course line from your present position, start at the compass rose. Line up one edge of the rule on the cross in the center of the compass rose, with that same edge projecting through the direction of your intended travel. Walk the rulers to your present position and draw the course line. This is how to plot a course of 225° True.
A good supply of 2B pencils are essential. 2B pencils are soft enough so they do not damage the chart and will keep a point for a reasonable period.
Many navigators now use a propelling type pencil as they do not require sharpening, if you choose this route, make sure it is not so hard that the lines you draw on the chart are too faint to be seen in poor lighting.
Selection of chart symbols
|Danger line in general|
|Wreck, least depth unknown but usually deeper than 20 metres|
|Wreck of which the mast(s) only are visible at Chart Datum|
|Wreck, least depth known obtained by sounding only|
|Wreck, least depth known, swept by wire drag or diver|
|or||Rock which covers and uncovers, height above Chart Datum|
|Rock awash at the level of Chart Datum|
|Underwater rock of unknown depth, dangerous to surface navigation|
|or||Underwater rock of known depth, dangerous to surface navigation|
|Remains of a wreck, or other foul area, non-dangerous to navigation but to be avoided by vessels anchoring, trawling etc.|
|Depth unknown, but considered to have a safe clearance to the depth shown|
|Sounding of doubtful depth; Existence doubtful; Reported, but not confirmed|
|Position approximate; Position doubtful|
|Tower; radio/television tower|
|Marina - boat harbour|
|Placeholder examples: Church (Ch) Tower (Tr) Hotel Cupola (Cu) Chimney (Chy).|
CAPITALS indicate that the landmark is conspicious.
|Major light; minor light |
|Limit of safety zone around offshore installation|
|Position of tabulated tidal stream data with designation “A”; Tidal levels data “a”|
|Green or black buoys (symbols filled black): G = Green ; B = Black|
|Single coloured buoys other than green and black: Y = Yellow ; R = Red|
|Multiple colours in horizontal bands, the colour sequence is from top to bottom|
|Multiple colours in vertical or diagonal stripes, the darker colour is given first. W = White |
|Lighted marks on multicoloured charts, GPS displays and chart plotters. A yellow coloured lobe indicates a White light! Also note that beacons (here the rightmost symbol with the green light) has an upright G, instead of an oblique G|
For those of you who are intersted this address shows 99% of the symbols used on Admiralty Charts.
This figure on the left shows the colour codes used for different depths on British Admiralty charts.
This is part of a free internet course at http://www.sailingissues.com/navcourse2.html
This is section is taken from chapter 2: below are other chapters for those nterested to study.
Chapter 1 - Positions
Chapter 2 - Nautical chart
Chapter 3 - Compass
Chapter 4 - Plotting
Chapter 5 - Piloting
Chapter 6 - Tides
Chapter 7 - Tide prediction
Chapter 8 - Currents
Chapter 9 - Navigation aids
Math - Running fixes
Math - Distance of horizon
Math - Vertical sextant angles
Compass deviation table
Lunation: phases of the moon