The friction of the water held the log in place as the ship sailed away from it. As the ship sailed away from the log, the sailors taking the reading would count the number of knots that passed over the rail in a period of half-a-minute. With records dating back to the 14th century and with likely use before in ancient times, the sand glass is a primitive timepiece used to measure the time usually 30 seconds at a time on a voyage, or on a specific navigational course.
The cross staff, also known as the early sextant, consists of a wooden rod with a sliding crosspiece used for measuring the altitude of a star. It is thought to have originated in the 14 th Century and was originally used as a land surveying instrument. Using the position of the stars to tell the time, the nocturnal was particularly primitive in design.
One ring was set to the date, Polaris was sighted through the hole in the centre and the arm was moved into a position to align with pointer stars. Where the arm crossed the marked ring, the time was read. Invented in , the backstaff is a navigational instrument that was used to measure the altitude of a celestial body, in particular the sun or moon. When observing the sun, users kept the sun to the back of them and observed the shadow cast by the upper vane on a horizon.
During the earlier years of the Board of Longitude, existing instrumentation was as inadequate for the accurate measurement of a Lunar Distance the angle between the Moon and selected reference stars as the Moon moves against the stellar background as was lunar theory for predicting lunar motion.
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Its quite helpful to all those involved in marine duties,am frm the nigerian navy , on my radar plotter course 1 final yaer. Thanks so muc for desining, this sites ,was very useful for me , because I am employee of marin company and I need to know about all of necessary devices a ship.
Sanam from Iran. Thank you. Marineinsight is the best site to give information about various shipping equipments in marine fields. It is very useful to all people who related to marine society. Your email address will not be published.
This website uses cookies to ensure you get the best experience on our website Got it! Download Practical Maritime eBooks With Amazing Bonuses: Here are a few fantastic ebooks to get important maritime information in the next couple of minutes! Image Credits: wikimedia. Image Credits: Nachiketh Bhattathiri. Report an Error. Want to share your tips and advice? Got questions? Visit the community forum to ask questions, get answers, meet people, and share your tips! Comments Thanx mate it was a short and sweet useful info.
Appreciate ur work. Thkx for dishing out the entics of today nav equipment for modern seafarer. Thkx for dishing out the entics of today nav equipment for modern seafarers. I learned a lot of navigation type And I like it. This information is very useful for me. It will help us to those study inBSMT. Just to thank you, atleast l learn types of Equipment inside the Ship.
I really enjoy reading. Papu: Thank you so much for the appreciation and support. Hi there! I think you forgot the palindrome palinorium. On my years it was an important equipment. Good Job. Beacons are fixed structures attached to the land or the seabed, and buoys are floating objects that are anchored in place. Both buoys and beacons can be lighted or unlighted. Navigational aids are marked on charts with unique symbols so mariners know what each marker means and how to navigate around it.
Here are a few common symbols for aids to navigation in U. These are only a few of the hundreds of symbols used to mark navigational aids on nautical charts. Chart No. Symbols for underwater dangers like reefs, rocks and wrecks also indicate the depth of the object and other significant characteristics. Although many of these symbols are self-explanatory, carrying U.
No nautical chart would be complete without a compass rose. A familiar symbol to any seasoned mariner, the compass rose contains three concentric circles marked with hashes and labeled with degrees. The outer circle of a compass rose points to true north, and the inner circles point to magnetic north.
If you are using a magnetic compass for navigation, refer to the inner circles when measuring your bearings. Marine chart plotting involves calculating the direction and distance of travel from your starting point to your final destination. This course may be a straight shot or involve multiple turns. By carefully marking the distance, direction and travel time for each leg on your nautical chart, you can navigate to your destination with confidence.
Chart plotting is fairly straightforward once you get the hang of it. Follow these steps for how to use a nautical chart to plot your sea voyage:.
Using the parallel ruler, divider and pencil, you can measure the direction and distance of each leg of your course and mark it on the nautical chart. The stopwatch will come in handy during your journey to track how far you have traveled and help you stay on course.
Locate the starting and ending points of your journey and draw a straight line between those points using your ruler. More complicated routes may require several turns to reach your final destination. Choose the route you want to travel based on water conditions and hazards, then mark each leg of the journey in a straight line using the edge of your parallel ruler or plotter.
Measure your direction of travel using the parallel plotter and compass rose on your nautical chart. Align the plotter with the first leg of your course and press one side down firmly. Move the other side of the plotter until its outside edge meets the small cross in the center of the compass rose.
The degree measurement on the magnetic compass rose is your bearing for that leg. Write the direction of travel in degrees magnetic next to that leg. Repeat this process for each leg of your journey. If you cannot reach the compass rose with a single movement, you can walk the parallel plotter across your chart by holding down one side and moving the other.
Because the two sides of parallel plotters always remain parallel, the angle will not change as long as you only move one side at a time. This ensures an accurate measurement of the direction of travel on even the largest nautical charts. Use your divider to measure the distance of each leg by placing one point of the divider at the beginning of the leg and the other point at the end.
Without changing the spread of the divider, move the divider to the latitude scale at the edge of your nautical chart.
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