Before assigning this activity, you might explain that a nautical mile is the distance of one minute, or 1/60th of a degree, of the equators 360-degree circumference.
Can You Fathom This?
Measuring Nautical Speed and Ocean Depth
Ships record their speed in knots. One knot is the speed of one nautical mile per hour. A nautical mile is 6,076 feet. On land a mile is 5,280 feet. Ocean depth is measured in fathoms, with one fathom equaling six feet. Use this information to solve the problems below.
|1. || How much longer is a nautical mile than a land mile? 796 feet longer |
|2. || A ship traveling 10 knots is traveling at what speed in land miles per hour? 11.5 miles per hour |
|3. || A sunken ship buried at a depth of 48 fathoms is how many feet below the surface of the water? 288 feet |
|4. ||(a) Some whales are said to dive half a mile below the surface. If the statement is referring to land miles, how many fathoms is this? 440 fathoms |
|(b) If this statement is referring to nautical miles, how many fathoms is this? 506 1/3 fathoms |
| ||Extra Credit: How did the term knot become used as a measure of speed? From counting the number of knots that ran out in the line tied to the chip log used to measure speed. |
Have on Hand- photocopies of blank worksheet
Blank Worksheet (pdf)