Chart Dividers

Chart DividersChart Dividers
Chart DividersChart Dividers

Chart dividers enable you to acquire the distance between that particular position and the nearest grid line. You place them on the scale with one end on this grid line. Two nautical dividers are used to get accurate coordinates from the chart. This device enables you to acquire the distance between that particular position and the nearest grid line.

You then place the dividers on the scale with one end on this grid line, allowing the other end to be accurately at your coordinate. Exercise this twice to acquire both latitude and longitude at the scale on the edge of the chart. 

Sufficient preparation is very crucial in piloting a boat.  Piloting is the primary process of determining a boat’s position by employing landmarks, other navigational aids, and soundings. In order for a boat operator to be capable of using good judgment on all decisions with reference to navigation the right tools and publications must be onboard and promptly available.

Consequently, it is crucial to be alert and attentive, and always be conscious of where your boat currently is and where it shortly will be. Boat operators should never commence underway without the appropriate charts or the following plotting tools:

Charts are indispensable for plotting and determining your position, whether manoeuvering in familiar or unfamiliar waters.

Parallel rulers are two rulers attached by straps that allow the rulers to separate whilst staying  parallel. They are applied in chart work to transfer directions from a compass rose to several plotted courses and bearing lines and vice versa. Parallel rulers are always walked so that the top or lower edge intersects the compass rose center to find accurate courses.

Dividers are instruments with two pointed legs, hinged where the upper ends join.  Dividers are used to measure distance on a scale and transfer them to a chart. Example of chart below.

Brass Chart DividersBrass Chart Dividers

Chart Dividers Combined Stop Watch and Light Lists

Nautical ChartNautical Chart


A Stopwatch is really valuable to determine the lighted period of a navigational aid. This is generally done for purposes of identification. Likewise it may be used to run a speed check.

It is all important to utilize a correct type of pencil for plotting. A medium pencil (No. 2) is best. Pencils should be kept sharp; a dull pencil can cause extensive error in plotting a course due to the width of the lead.

Light Lists supply more complete information regarding aids to navigation than can be shown on charts.  They are not specified to replace charts for navigation and are published in seven volumes.


Tide Tables

Tide Tables present daily predictions of the height of water, at virtually any place, at any given time, and are published each year in four volumes.  Operating instructions for applying the tables are supplied inside the publication.

Tidal current tables supply the times of maximum flood and ebb currents, and times of the two slack waters when current direction reverses.  They in addition tell the predicted force of the current in knots.  The time of slack tide doesn't correspond to times of high and low tide. The tide tables can't be applied for current predictions.  The tables are published in two volumes.  Instructions for applying the tables are supplied inside the publication.

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