Cara Menentukan Posisi Kapal dengan baringan Silang

Summary

This tutorial explains the technique of determining a ship's true position using 'cross bearings' (baringan silang). The process involves plotting lines from two visible landmarks on the map, adjusting for compass variations, and using true bearing calculations. The tutorial walks through detailed steps for determining the ship's heading, true bearings of objects, and visualizing the results on nautical charts. The method is explained with a practical example, showing how to compute and draw true bearings and determine the actual position of the ship. This method helps in precise navigation and correcting GPS discrepancies.

Takeaways

• 😀 The 'bearing cross' technique is used to determine the true position of a ship by drawing lines from two visible landmarks and finding their intersection.
• 😀 To accurately perform bearing cross, the ship's heading must first be adjusted to the true heading, considering both magnetic variation and compass deviation.
• 😀 The ship's heading must be corrected using the formula: True Heading = Compass Heading + Variation + Deviation.
• 😀 Two visible landmarks, such as lighthouses, are chosen to create bearings that are then adjusted to become true bearings using the variation and deviation.
• 😀 After correcting the compass bearings to true bearings, lines are drawn on a nautical chart using a compass rose to indicate the true bearings of the objects from the ship.
• 😀 The intersection of the two true bearing lines represents the ship's true position, also known as the 'true position of the ship'.
• 😀 The ship's initial position, determined by GPS, is called the 'estimated position' (EP) and can be different from the true position due to navigational errors.
• 😀 The difference between the estimated position and the true position is called 'dead reckoning error' or 'DR error'.
• 😀 The script provides a detailed example where a ship's heading and two bearings from visible objects (lighthouses) are used to calculate and plot the ship's true position on the map.
• 😀 To draw the true bearing lines on the map, the user must move the protractor and ruler to mark the angles accurately, which leads to determining the ship's true position and heading.

Q & A

What is the main concept of 'bearing crossing' in navigation?

Bearing crossing is a technique used to determine a ship's true position by intersecting two bearing lines from land-based objects. The intersection of these lines reveals the ship's actual position.

What is the first step in creating bearing lines in bearing crossing?

The first step is to establish the ship's true heading. This requires converting the ship's compass heading to its true heading by considering the variation (on the nautical chart) and the compass deviation.

How do you correct a ship's compass heading to its true heading?

To correct the compass heading to the true heading, you use the formula: True Heading = Compass Heading + Variation + Deviation. The signs (positive or negative) of variation and deviation depend on their direction (East or West).

What do you do after determining the true heading of the ship?

After determining the true heading, you draw the bearing lines on the nautical chart based on the observed positions of two visible objects, using the correct true bearings for each.

How is 'salah duga' (error in position) defined in this context?

'Salah duga' refers to the difference between the estimated position of the ship (using GPS) and its true position (determined by bearing crossing).

What are the two visible objects used in bearing crossing for determining position?

The two visible objects can be landmarks such as lighthouses, which must be identified on the nautical chart for accurate bearing determination.

How do you calculate the true bearing of an object?

To calculate the true bearing, you adjust the observed compass bearing by adding or subtracting the variation and deviation. The formula is: True Bearing = Compass Bearing + Variation + Deviation.

What is the significance of the intersection of bearing lines in navigation?

The intersection of the bearing lines indicates the true position of the ship. It is the point where the ship’s actual location can be pinpointed on the chart.

How do you draw the bearing lines on a nautical chart?

To draw the bearing lines, use a compass or protractor on the chart. Start by drawing the ship's true heading, then plot the true bearings to the objects (like lighthouses) and extend the lines until they intersect.

What role does the 'mawar pedoman' (compass rose) play in determining bearings?

The 'mawar pedoman' (compass rose) is used as a reference for determining the true bearing angles. It provides the directionality necessary to accurately plot bearings and headings on the chart.