Practice first in an area where there are lighted aids to navigation, but not too many lights on shore behind the aids to obscure them when you look toward the shore from seaward. Your home area may be best if the conditions are right. (1) make a list of the characteristics of the lights in the area; (2) go out before sunset, look at all the familiar buoys and lights in daylight; (3) from a relatively stationary location (anchor or drive around slowly), observe the lights as they come on as it gets dark; (4) compare what you see to the chart, and note where shore lights may interfere with seeing the lights on the aids to navigation. Once you are familiar with the lights in your home area, you are ready to try new areas at dusk and then in the dark. Remember to turn on your boat’s navigation lights at sunset. Check them before you go out.
Some boaters may worry about being caught out after dark or having to do a trip during the night hours. If you never go out at night or really believe that you will never be caught out after dark, then perhaps you don’t need to worry about navigating at night. However, it’s a relatively easy skill to master with practice, and sometimes navigating at night is actually easier than in the day.
Practice first in an area where there are lighted aids to navigation, but not too many lights on shore behind the aids to obscure them when you look toward the shore from seaward. Your home area may be best if the conditions are right. (1) make a list of the characteristics of the lights in the area; (2) go out before sunset, look at all the familiar buoys and lights in daylight; (3) from a relatively stationary location (anchor or drive around slowly), observe the lights as they come on as it gets dark; (4) compare what you see to the chart, and note where shore lights may interfere with seeing the lights on the aids to navigation. Once you are familiar with the lights in your home area, you are ready to try new areas at dusk and then in the dark. Remember to turn on your boat’s navigation lights at sunset. Check them before you go out.
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What happens to the water when the wind blows in opposition to a current? (The word “tide” is often used as a synonym for current, as in “wind against tide”). If you’ve never encountered this in your travels you may not know. If you’ve been in a wind against current situation, you probably remember. A strong current flowing against a strong wind can produce waves that may be dangerous to vessels of all sizes, and in some places only a moderate wind against a current can produce uncomfortable or even dangerous conditions.
When the wind opposes the current, the wave height increases and the wave length (distance between wave crests) decreases. You get short, steep seas. Fortunately, most cruising guides and some charts indicate locations where these conditions may occur. Wind with current decreases the wave height and increases the wave length, so it’s not as dangerous, but the conditions could still be challenging to navigate. Do you know what dead reckoning is and how to use it? DR is used to calculate a boat’s position along an actual or proposed course line, using the time underway and the speed of the vessel. With GPS on so many boats, people don’t seem to bother much with dead reckoning arithmetic these days, because the GPS can easily calculate time, speed, and distance while navigating toward a waypoint. Dead reckoning is used to plan a trip and to keep track of your progress independently of the boat’s instruments.
Use DR calculations to double check your boat’s position visually and on the chart. Use DR calculations to determine when you should be able to see a particular aid to navigation or landmark based on your boat’s speed and present position. Can you answer the following DR questions? (1) What speed must I maintain to go 45 miles in the six hours before it gets dark? Speed = distance divided by time. (2) The top speed of my boat is about 12 knots; how far can I go in 10 hours? Distance = speed x time. (3) My boat’s average speed is 8 knots; how long will it take me to travel 130 miles? Time = distance divided by speed. If these little problems are easy for you, it will be a snap to keep a DR plot on the chart or in a log, so you have a backup to your electronics. For the arithmetically-challenged you can buy an inexpensive flat, plastic device called a nautical slide rule, to do the calculations visually. Weems and Plath product #105 is one model. No batteries needed and no formulas to remember! Whether you use paper or electronic charts you must learn what the symbols, colors, and notations mean. In the U.S. and other countries there is a publication (paper and electronic) called Chart No. 1, which has all the chart symbols and words used on charts published by a particular country. In the U.S. you can download Chart No. 1 from www.nauticalcharts.noaa.gov/mcd/chartno1.htm. (In 2012 paper copies were not being printed by the U.S. government, but plans are being made for chart agents to be authorized to print paper copies.). An excellent source for a paper copy is Nigel Calder’s book, How to Read a Nautical Chart (A Complete Guide to the Symbols, Abbreviations, and Nautical Data Displayed on Nautical Charts). It has all of Chart No. 1, plus detailed explanations. Nautical bookstores and on-line booksellers stock this book. It should be aboard every boat that uses charts – you can’t remember everything and unfamiliar symbols may be very important to know.
A small-scale chart shows a large area in less detail and a large scale chart shows a small area in greater detail. A harbor chart is a large-scale chart; a chart of the North Atlantic from Newfoundland to Ireland is a small-scale chart. There are four basic scale categories: sailing charts (crossing an ocean); general charts (coastwise navigation outside off-lying dangers and usually in sight of land); coastal charts (navigation near shore and entering harbors); harbor charts (details of harbors). Chartlets found on some charts and in cruising guides or nautical almanacs may have really large scales. Zooming in to a particular area on a small scale electronic chart may not show the same detailed information that would be found on a large scale chart of the same area.
Even if you have GPS and a chart plotter, all boats need a reliable magnetic compass. If the electronics fail or become unreliable the compass will help get you home, assuming that the compass is accurate and you have a paper chart. Check out the compass entries in the Mariner’s Guide on pp. 106-109, determine the alignment error (p. 14), check for deviation and make a deviation table (pp. 134-135). An accurate compass is an essential safety device.
Make a list of the factors you think may affect the reliability of aids to navigation. Then look at aids to navigation, cautions, Mariner's Guide pp.12-13, and see if you can add anything to the list. Please send your additions via the website contact form
Professional Mariner magazine, April 2012, reviewed some of the actions which contributed to the incident. There are lessons for all mariners in charge of a vessel, large or small. (1) Don’t be encouraged by people aboard into taking the vessel into waters that might be dangerous just to get a closer look at something or to give the people on shore a good look at your boat. A close-up view or a photo opportunity is not worth taking a risk. (2) If you decide to take the vessel into possibly unsafe waters what would you do if an essential system, such as the steering or the engine, fails? Do you know if there’s room for error? (3) Even when navigating in familiar waters always use at least two independent methods of fixing the vessel’s position at frequent intervals to be sure you stay in safe water. There’s a temptation to assume “I’ve done this route so often I can eyeball it.” These three points may be basic concepts to many boaters, but they were apparently forgotten or ignored in the Costa Concordia incident.
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AuthorPriscilla Travis spends more than 110 days each year on the water, takes photos, and writes about nautical topics. Archives
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