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Reducing the power draw of the vessels anchor light
The international COLREGS state that an anchored boat must display a round ball when anchored during the day and an all-around white light at night. The light must be an all-round white light which is visible for 5 miles for vessels between 12–50 metres (39–164 ft) and at least two nautical miles for vessels smaller than this. It must be placed in the forepart of the vessel or “where it can best be seen”. Maintaining these lights throughout the night draws a lot of power.

Reef navigation
Sailing in reef strewn waters is very dangerous. The only safe way to operate in tight reef waters is to use eyeball navigation. To do this you need to get at least six feet above deck level to view the patterns on the water.

Dealing with the three different GPS conventions for describing a waypoint
GPS has forever transformed the art of navigation, but there are sublties of expressing a position that need to be understood. There are three different GPS conventions for describing a waypoint, it is imperative for accuracy of position that you understand which convention you are using aboard and format of information you are being provided from external sources.

'Rule of Twelfths': a simple method for estimating intermediate tidal heights
Applying a graphical procedure, found by reference to an appropriate almanac and the times and heights of high and low water, a navigator may precisely work out intermediate tidal heights and times. This then enables depth restricted vessels to pass into shallow waters supported by tidal water and accurately plot a position where a vessel may anchor and stay afloat.However plotting tide to this level of detail is a skilled, onerous and time consuming task. It is for many cruisers more for the world of merchant sailors. Moreover, tidal curves are often only available for major ports where most leisure vessels would have ample water, not in out of the way anchorages. In the real world, even if the detail is available, few sailors would go to this level of detail.

Keeping track of tides when sailing in tidal affected areas
Sailing in tidal waters requires constant vigilance and quick maths to make best use of currents. As the tide times are constantly changing and there are many distractions on a sailing vessel, it is easy to forget the tidal times or make an error of maths.

A tide and current predictor when cruising in unfamiliar waters
When crossing oceans and seas to new sailing destinations it is not easy to have arrival tidal data. Typically boats acquire local tidal data after landing.

Clearing hazards with a danger bearing
Whether you are navigating by instrument or eyeball, what lies beneath the water is invisible in most places. And sometimes, the main concern of navigation is to avoid these hidden dangers such as extensive reefs or shoals. A good example that can be used to illustrate the problem is the Shingles Bank, on the western entrance to The Solent on the south coast of England. It is marked by several lighted buoys on the southeast side, or channel side, but none on the north side. Given its numerous shallow patches and rapidity of the tides it has all the ingredients to put any vessel which might have the misfortune to come up on it in pearl. But likewise there is deep water to the north and a settled conditions, good visibility cut between North Head bank and the Shingles keeping Hurst Castle open of its own width of Fort Victoria - see Solent Coastal Description. The problem with this is that the dangerous Shingles Bank lies close and mostly covered making it risky.

Harbour information at your fingertips
Harbour information can be spread across a range of pilot books, tidal books and ports etc. Bringing the information together when required, requires time to dig and search through reams of pages and indices.

How to tell if you are on a collision course with another vessel
One of the most perplexing problems for newcomers to sailing is trying to assess converging courses of surrounding vessels and knowing how to judge who's going to cross whom. Sailing novices tend to be familiar with driving automobiles where it is easy to detect the possible risk of a collision with implicit reference to the background (e.g., the roads, the scenery, the landscape, etc.) At sea, when vessels are borne in water, the sea surface removes all visual clues obsoleting to a large part terrestrial instinct.

Getting to grips with sound signals
In busy waterways large vessels use sound signals to notify nearby boats of their intentions.


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