[vc_row][vc_column width=”2/3″][vc_single_image image=”123072″ img_size=”full” alignment=”center” style=”vc_box_border”][vc_column_text]While distances and speeds on land are configured in miles or kilometres, pilots flying aircraft or captains on ships use nautical miles and knots. The reason? Both are based on the circumference of the earth, making life a lot easier for global aviators and sailors. (For the record, nautical miles are also used for polar exploration and international laws and treaties regarding territorial water limits.)
These days, it can all be done electronically with a vast variety of gadgets on sale at your local boat supply store, nautically known as a chandlery.
Can you go the distance?
1 nautical mile = 1.1508 miles or 1.852 kilometres
Nautical miles are used for charting and navigating, and knots are the seafaring unit for a vessel’s speed.
A nautical mile is based on the circumference of the earth, and corresponds to one minute of latitude. It is slightly more than a statute (land measured) mile.
While the origins of this measurement method go back to the 15th century, there was no internationally agreed distance or definition for the nautical mile until 1929.
In that year, the First International Extraordinary Hydrographic Conference was held in Monaco and it was determined that the international nautical mile would be exactly 6,076 feet (1,852 metres).
While many countries accepted this, the United States continued with its own definition which added an extra metre to the length — not much in terms of a short distance, but plainly noticeable on a long journey. In 1954, it relented and joined the Monaco clan.
Meanwhile, the United Kingdom clung to its method of equating the distance to the knot, but finally surrendered to international pressure in 1970.
Are you up to speed?
1 knot = 1.15 mph or 1.85 kph, meaning one nautical mile per hour.
The term ‘knot’ dates from the 17th century. In those days sailors measured the speed of their ship by using a device called a “common log” or “chip log”.
This device was a coil of rope with uniformly spaced knots, attached to a chip of wood shaped like a slice of pie. The wood was lowered from the back of the ship and, as the vessel moved forward, line came off the coil. Crew members kept track of how many knots went overboard during a given period. The number of knots counted represented the speed of the ship in knots, or nautical miles, per hour.
By knowing his ship’s average speed over the course of a day, the captain could determine how far the ship had travelled. Incidentally, the equivalent of a stop watch in those days was the sand timer — still available, albeit with the wood and glass replaced by plastic, but ideal for timing the boiling of eggs!
Can you fathom this out?
A fathom is a unit of length equal to six feet, or nearly two metres, and used for determining the depth of water a vessel is in. The distance of six feet was decided centuries ago on the hand-to-hand width of a man with outstretched arms — and not its modern usage of describing the size of the fish that got away.
Nowadays, it is all done by computers with devices on sale that tell you not just how deep is the water, but whether there are any fish around. A far cry from those ancient times.
Then, sailors used a contraption called a lead line. This was simply a hemp rope with a heavy piece of lead tied to one end. A mark was made on the rope every six feet and a crew member would throw it overboard, counting the marks on the line as it sank to the bottom. By multiplying the number of marks by six once the rope went slack, the sailor could figure out how deep the water was at that spot.
More sophisticated lead lines also had an extra function. In the base of the lead weight was a hollow groove that the sailors filled with wax. When the weight hit the bottom, the wax collected sand, mud, or other contents of the ocean floor. If a captain knew the depth of the water and the nature of the seabed, it helped determine how safe his ship would be at anchor — meaning would it hold position or be dragged by the current.
Finally, for those wondering whether there is a connection between a fathom and a verb of the same name, the answer is yes. Figuratively speaking, to ‘fathom’ something out, is to get to the bottom of it. Detectives do it all the time.[/vc_column_text][/vc_column][vc_column width=”1/3″ css=”.vc_custom_1493287908238{background-color: #f3f3f3 !important;}”][vc_widget_sidebar sidebar_id=”nautical-novice-series”][/vc_column][/vc_row][vc_row css=”.vc_custom_1493210266709{margin-bottom: 14px !important;}”][vc_column width=”2/3″][vc_column_text]
[/vc_column_text][/vc_column][vc_column width=”1/3″][/vc_column][/vc_row][vc_row css=”.vc_custom_1493210178216{margin-bottom: 0px !important;}”][vc_column width=”2/3″][vc_column_text]
[/vc_column_text][/vc_column][vc_column width=”1/3″][/vc_column][/vc_row][vc_row][vc_column width=”2/3″][vc_column_text]
[/vc_column_text][/vc_column][vc_column width=”1/3″][/vc_column][/vc_row][vc_row css=”.vc_custom_1492972597552{margin-top: -10px !important;}”][vc_column width=”2/3″][vc_single_image image=”123014″ img_size=”full” alignment=”center” style=”vc_box_shadow_border”][vc_column_text css=”.vc_custom_1493310533617{margin-top: -14px !important;border-top-width: 6px !important;border-right-width: 6px !important;border-bottom-width: 6px !important;border-left-width: 6px !important;padding-top: 20px !important;padding-bottom: 20px !important;background-color: #ffffff !important;border-left-color: #072f62 !important;border-left-style: solid !important;border-right-color: #072f62 !important;border-right-style: solid !important;border-top-color: #072f62 !important;border-top-style: solid !important;border-bottom-color: #072f62 !important;border-bottom-style: solid !important;}”]
Selling an outboard engine, a catamaran or anything that’s nautical?
If it’s a private sale we will carry your advert for FREE in our classified section.
Just fill in the form and we shall do the rest.
[/vc_column_text][/vc_column][vc_column width=”1/3″][/vc_column][/vc_row]
