PowerPoint Presentation

[Audio] Welcome ladies and gentlemen. We are excited to present to you today this informative workshop on coastal navigation. We will discuss definitions, fixing, plotting, calculation, dead reckoning, estimated positions, transits, and tidal streams. Sit back, relax and get ready for some in-depth knowledge on this fascinating subject..

[Audio] For this slide, I will be discussing the various contents covered in the workshop. This workshop provides a comprehensive overview of coastal navigation techniques, covering definitions, fixing, plotting, and calculations. We'll also have some exercises to practice what we have learned. Let's get started!.

[Audio] When navigating a vessel on the coast, it's important to keep track of your location along the course. This is done through a practice known as dead reckoning. To do this, a small line is drawn across the chart from the course being steered. The time is written alongside the line and a small cross may be used to start the DR if a fix or estimated position is not available..

[Audio] At Estimated Position, marking a dot on the chart surrounded by a small triangle is a quick and easy way to plot the ship's position. The time should be noted beside the EP dot to give a clear indication of when the ship was at that point. The navigation track should pass through the EP dot and the ship's voyage can be plotted further by continuing the ground track. This should be followed to bring the ship to its designated destination..

[Audio] Navigation is a complex and time-honored art that requires an understanding of the principles behind calculating a ship's position. DR and EP are two essential methods for achieving this, whereby DR stands for Dead Reckoning - the position of a ship obtained by the true course steered and its speed through the water, and EP stands for Estimated Position - a more accurate position obtained through calculation and estimation. Through the use of DR and EP, navigators can determine the exact location of the ship, taking into account the effects of the environment on the movements of the ship. This table provides all the essential data needed to determine the EP Position, offering a great way to ensure that the navigator is always aware of where the ship is at any given time..

[Audio] A table of data related to DR and EP plotting is presented in the slide. DR, which stands for Dead Reckoning, is the calculation of position based on the course and speed being steered. EP, meaning Estimated Position, must be calculated manually by determining the relevant factors. The DR position is represented on the chart as a small line drawn across the course being steered with a small cross and the time alongside. EP appears on the chart as a dot surrounded by a small triangle, with the time alongside..

[Audio] Navigating the coast can be tricky, but transits are a great way to track your vessel's progress and accuracy. When dealing with transits, keep in mind that if two fixed objects are in line, you must be directly on the extension of the line connecting them. It is also necessary to maintain the correct distances. Ideally, the distance between the ship and the nearer object should be no more than three times the distance between the two objects. Doing so will assist you in precisely monitoring the relative movement between the objects and even turning at rest with assurance..

[Audio] Tidal streams are a result of the gravitational forces of the sun and moon creating a periodic horizontal movement of the sea surface. Caution should be taken when utilizing tidal stream data, particularly during springs and while transitioning from ebbing to flooding and vice versa. Oftentimes, the real tidal stream differs from the forecasted..

[Audio] Coastal navigation requires taking into account the currents of the sea, which can vary from steady and consistent to changeable with meteorological conditions. Drift currents are common, and they should be accounted for when planning a route..

[Audio] Leeway is an important consideration when navigating a vessel on the coast. Leeway is the force of the wind pushing the vessel in a direction to leeward, at a right angle to the course steered. Various factors affect the leeway such as the vessel's speed, the speed and angle of the wind, the longitudinal area of the vessel and the depth of the water. Generally, as the speed of the vessel increases, the leeway decreases. Conversely, the higher the component of the wind speed at a right angle to the course, the greater the leeway; and the shallower the water is in relation to the draught, the less the leeway. Knowing how these factors influence leeway is essential for safe navigation..

[Audio] The data table shows how leeway effect increases with the speed of the vessel. At 10 knots, the leeway effect is significantly lower than at 30 knots. At 20 knots, most vessels are able to achieve a leeway of less than 0.1 knots. It is clear that ship's speed has a direct correlation to leeway, and that the faster the ship moves, the greater the leeway effect will be..

[Audio] Understanding surface drift is crucial for successful navigation along a coastline. The maximum rate of surface drift is usually a fortieth of the wind speed and it can reach full strength within 6 to 48 hours, but this can depend on the length of time the wind has been blowing and the range it has been able to cover, known as the 'fetch'. In more extreme cases like hurricanes, the current can reach up to two knots. Also, surface drift can be a factor in the piling up of water along a coast..

[Audio] Surface drift is an important factor to take into consideration when taking part in a coastal navigation workshop. It typically moves the boat in a specific direction at a rate of approximately half a knot, leaning anywhere between 20° and 45° relative to the wind direction in the Northern Hemisphere, and to the left in the Southern Hemisphere, with a direction between 245° and 270°. This, combined with the effects of the current and tidal stream, can alter the distance covered over a period of time; making it necessary to factor in when preparing for a coastal navigation event..

[Audio] Fixing on a chart is represented by a dot surrounded by a circle, with the corresponding time written next to it. Position lines form a reference for the fix and a suffix can be added if necessary to indicate the type of navigational aid being utilized..

[Audio] When navigatng, it is crucial to plan ahead and contemplate the techniques for determining the vessel's position. Factors such as the rate of determining the position, the speed of the ship, and the duration of getting the coordinates must be considered. Adequately recording all of the data is essential for the voyage's accomplishment. All these elements must be considered when planning the voyage of the vessel..

[Audio] The slide will cover different types of fixing. First, the bearing fix which uses angles from reference points to find one's position and is usually found on GPS receivers. Second, the range fix which involves the use of distances from two or more points to calculate the position. Lastly, the running fix which involves taking several bearings of the same objects over a period of time to determine the vessel's position..

[Audio] When determining the ship's position, visual bearings should be prioritised as they are more accurate. Taking a bearing of a vertical edge of an object can provide a more precise bearing. Although a radar bearing can be taken as an alternative when conditions do not permit a visual bearing, these should not be used to plot a position line as they are usually less accurate. To obtain a true indication of the ship's position, two or more bearings of different objects should be taken simultaneously..

[Audio] Radar can be useful to assist in navigating near the shore. It allows for getting a positional line from two or more stationary things. Calculating the distances from two or more objects to our present location, and mapping those distances out, helps to exactly pinpoint our heading and positioning. This can be extremely beneficial to all navigators..

[Audio] We are discussing how to use two or more ranges when fixing our location on the coast. To do this, we must first select three or more conspicuous land features that can be clearly plotted on the RADAR PPI. Then we must take the ranges from all these points at the same time, for example A, B and C. This will allow us to accurately fix our location..

[Audio] Measure a range of 1.3 nautical miles from point A using a chart and plotter. Mark the same measurement extending in a straight line from point A on the chart. This line is referred to as a position line and can be used to determine one's location..

3.3 nm. B. Now draw a range line by 3.3 nm from point B.

[Audio] Draw a range line from point C, using a 4.5 nautical mile range by drawing a straight line eqidistant from point A and B, originating from point C. This range provides a 4.5 nautical mile radius for any object, bearing, or course to be taken when navigating our coastal waters..

[Audio] In this slide, we see three lines that intersect at a single point - which is the fix of the ship at that particular time. This is shown on the chart as a dot surrounded by a circle. It's important to remember that the fix allows the navigator to pinpoint the exact position of the ship..

[Audio] A Transferred Position Line is a useful navigational tool for taking into account the effects of wind and tides on the course of the ship. It can be used for various purposes, including a Running Fix, ensuring the safety of the vessel while entering a poorly defined anchor or port, and plotting an Astronomical Position Line while performing Astro navigation..

[Audio] At 1630, the ship should plot a new position line from its current position, by taking a bearing of 215° towards the lighthouse. This new position line is the Transferred Position Line, and it will intersect the Position Line from the lighthouse. This will give the new position of the ship at 1630 - point A..

[Audio] At 1630, if you had assumed that the ship was at point A on the Position Line running from the lighthouse, you would have been able to project a Transferred Position Line in a direction equivalent to a 30 minute run, 090-4', passing through point B. This Transferred Position Line should contain a double arrowhead at its outer end and would be parallel to the original Position Line..

[Audio] To plot the transferred position line accurately, you need to consider the speed, course, and the time elapsed. You also need to calculate the tidal stream vector, making sure you account for the direction and speed of the water current. Think of the tidal stream vector as a wind vector, just underwater instead of above ground. Plotting the line with all of this in consideration will give us the most accurate position line for the ship..

[Audio] In this example, we will be looking at transferring a position line and accounting for tidal streams. This means plotting the wheel-over position of the vessel, and then transferring the 080° Position Line AL through it, calculating the time it will take the ship to reach the transferred position line. Additionally, we must also take into account external influences such as wind and tidal streams. The procedure at Example-2 outlines the steps to take to do this..

[Audio] Accuracy of a Running Fix depends on an accurate assessment of the ship's course and speed, as well as the effects of wind and Tidal Streams or Currents. Errors arising from inaccuracies in Drift or Set can lead to major mistakes. The next slide shows how conditions such as these have an impact on the lives of people living in impoverished urban areas..

[Audio] The ship's position at 1630 can be determined by taking a Standard Running Fix, which involves taking the course and speed of the ship at 1600 and transferring the position line to 1630. Along with that, a second position line is determined by taking the bearing of the lighthouse at 1630. The point of intersection of these two position lines will be the ship's position at 1630. To achieve accuracy, the tidal stream also needs to be taken into account..

[Audio] Our vessel's position at 1630 can be found by plotting the transferred position line, taking into account the tidal stream, and the 1630 position line intersecting at 295 degrees..

[Audio] A ship at a known location was observed to be on course 180° at 1700. An object R was taken to have a bearing of 090° at 1800, and the same object was taken again to have a bearing of 053° at 1836. Through the running fix method, we can thus estimate the drift and set experienced from 1700 to 1836, and use this to determine the tidal stream in the area..

[Audio] Starting from the 1700 Fix at A, plot the ship's water track at AE, which is at 180° from A. Then plot the 1st Position Line, which intersects AE at B. Using the speed and AB, the Transferred Position Line can be plotted at the EP position at 1836. Let's go over this process and examine how to apply it..

1836 2nd Posn Line. Tidal Stream. P 1836 Running fix posn.

[Audio] Ship had been given a course and speed of 090 degrees and 15 knots respectively at 7am. After an hour of travel, the course steered as recorded by the plotting table was 090 and a half degrees and speed through the water was 14.7 knots. Taking into consideration the tidal stream, current and surface drift, the estimated position must be plotted after 1 hour to deduce the course and speed made good, as well as the set and drift. The ship is located in the Northern Hemisphere..

[Audio] Plotting a course is essential for our journey. We must comprehend and anticipate the leeway vector, the predicted surface drift, and map out the DR position. We need to determine the direction and speed of the course we steer, to measure the distance between our starting point and our destination. It is absolutely essential to accurately plot in order to guarantee a successful journey. Let's begin..

[Audio] We need to plot the leeway from Point A to Point B, bearing 000½° and speed of 0.75 kn. Next, plot the tidal stream from Point C to Point D, bearing 295° and speed of 1.5 kn. Then, plot the current from Point D to Point E, bearing 060° and speed of 0.75 kn. Finally, plot the surface drift from Point E to Point F, bearing 030° and speed of 0.5 kn. Calculate the course steered from Point A to Point F, which is 090.5, and the drift of 14.7. With this information, we can find our true water track and reach our final destination, Point F..

[Audio] I am presenting a slide centered around plotting. The example on the slide covers the resolution of all four factors in the plotting process, though normally we just encounter one or two of them. It is essential to take all four of these factors into account when plotting, making sure that the ground track is correct and the set and drift is considered. This slide should have provided everybody with the assurance to take on plotting for their navigation tasks..

[Audio] A ship travelling from point A to lighthouse L must calculate the time when it is abeam of the lighthouse. This calculation takes into account the ship's speed and the tidal stream setting 345⁰. With these two factors, the ship can determine when it will be 2 miles away from the lighthouse, which indicates the abeam position..

[Audio] We will start by drawing an arc of a circle with a radius of 2’ from point L. At the same time, a tangent will be drawn from the ship’s present position to the arc. This will create the desired ground track from point A to D. To find the correct course to steer from A to B, we will use the method given in example 7-1. Remember that when the ship is at point E, which is 90⁰ from the course steered, we have reached the light. The time is calculated by the distance AE with the help of the Ground speed represented by AC and not the Closest point of Approach [CPA]-2 miles..

[Audio] As we discuss coastal navigation, it is important to understand the concept of rising and dipping. The Rising or Dipping Range is the range at which objects are observed to appear above or below the horizon. Its accuracy is substantially affected by Atmospheric Refraction and should be treated with care. At night, this method can be used to calculate the distance of a light when it first appears above or dips below the horizon. The theoretical distance of the sea horizon for a height of h metres is 1.92 sea miles, however, due to Atmospheric Refraction, this is increased by approximately 8%. The formulas to find the distance of the sea horizon are Distance = 2.08 √h sea miles, where h is measured in metres, or Distance = 1.15 √h sea miles, where h is measured in feet..

[Audio] Without greetings and without beginning with 'Today': This slide explains how we can calculate the range of a light beyond the horizon when observed from the bridge of a ship. Knowing the height of the structure, which is 40 metres from the water and the height of eye or the height of observation is 12 metres above the water, we can use the formula to determine that the range of horizon for a height of eye of 12 metres is 7.21 sea miles and the range of horizon for a height of eye of 40 metres is 13.16 sea miles. Consequently, the range of the light is 20.37 sea miles. This is a useful tool to learn more about coastal navigation. I would like to thank you all for attending this workshop and listening to me..