Author page: nautica

Use of divider measuring distance 1

How do you measure a distance using the dividers? Let’s assume you sail from point A to point B. The true course is 110°, and you want to find how many nautical miles it is from A to B. In other words, the distance from A to B. Place one...

Use of divider measuring distance 2

How do you measure a distance that is longer that the span of your dividers? Assume that you are sailing from point A to point B. The true course is 110°, and you want to know how many nautical miles it is from A to B. However, the distance to be...

Use of divider applying a meassured distance

How do you apply a measured distance using the divider? Let’s assume you calculate a distance of 10.5 nautical miles, and you want to apply it in your true course starting at point A, assuming your true course is 110 degrees. Use the...

When we are on an open sea passage out of sight of land, at night or in a dense fog, we must be able to keep an accurate track of our position and course at all times. There are many ways we can do this, and many techniques we can use for finding...

Estimated position

If we apply the set and the drift of the tide to the 11:30 Dead Reckoning (DR) position, we will have converted this position to an 11:30 Estimated Position (EP). To work out the set (direction) and the drift (speed) of the tide, we refer to the...

Application of variation 1

True North is the direction towards the Geographic North Pole. On a nautical chart, all lines of longitude are aligned to the True North. Magnetic North is the direction towards the Magnetic North Pole. The angular difference between True North...

Application of variation 2

On every nautical chart there is at least one Compass Rose. The Compass Rose consists of the following: the outer rose, which is aligned with the True North and the inner rose, which is aligned to Magnetic North. Near the center of the Compass...

Application of variation 3

On a nautical chart, to convert a True Course to a Magnetic course, or to convert a True Bearing to a Magnetic bearing you must apply the following formula: From True to Magnetic, add the Westerly Variation and subtract the Easterly Variation. To...

Application of variation 4

Your True Course is 020 degrees and the Magnetic Variation for the year of 1993 is 6 degrees and 00 minutes West. The annual rate of change is increasing 7 minutes, your task is to calculate the Magnetic Variation for the current year, and to...

Application of deviation 1

The difference between the direction of Magnetic North and the direction that the compass points to is known as Magnetic Deviation. Compass deviation is caused by the environmental influences on your compass. On the boat, it can be influenced by...

Application of deviation 2

Use your Deviation Card to convert between Magnetic and Compass Courses. To create a Deviation Card, steer an accurate course of due North (000 degrees compass). Take a hand bearing compass to sight along the centerline of the boat and position...

Application of deviation 3

In the previous lessons you learned to calculate the Magnetic Variation and also to find out the Magnetic Deviation by using the Deviation Card. Let’s assume that the True Course plotted on the chart is 020 degrees, the Variation is 3...

Application of deviation 4

Let’s assume that your boat is on a Compass Course of 018 degrees, and you want to convert the course to a True Course so you can plot it on the chart. The Deviation is 5 degrees East and the Variation is 3 degrees West. To find out the...

Use transits to check compass error

Transits are not only used to determine your position line, they can also be used to check your compass error. On your chart, look for two objects in line. As you already know, transits can be man-made objects or natural ones. So, the two objects...

Steering compass 1

Your boat should be equipped with a good quality steering compass. There are two types of steering compasses: the conventional compass and the fluxgate compass. The conventional compass has two or more magnets attached to the underside of the...

Steering compass 2

When mounting a steering compass in a boat, be aware of the following recommendations: 1.the compass must be mounted with the lubber line coinciding with the boat’s fore-and-aft line 2.the compass must be mounted so as to be seen easily by...

Hand held compass

A hand held compass is used to obtain compass bearings on shore or floating objects. Simply line up the sighting line with the object and read off the bearing in degrees. When using a hand-bearing compass keep it away from metal objects and...

Passage plan

All vessels need a passage plan What is a passage plan and how do you create one. A passage plan helps to bring the vessel and the crew safely from berth to berth. Durring your voiage you may experience rough weather, fog, strong tides etc...

Passage plan stages

A passage plan has 4 stages, Appraisal, Planning, Execution, Monitoring. In appraisal stage all information relevant to the contemplated passage should be considered. In a planning stage, based on al information available, a detailed voyage plan...

Passage plan appraisal stage

Lets have a closer look at all 4 stages. Appraisal is a gathering together of all information Navigational informationa on charts Information from publications Sailing directions, light lists, current atlas, Tidal atlas, tide tables and notices...