The Three Minute Rule.
The Minute Rule is a trick that navigators have used for a very long time. Its very simple way to figure out how far you are going to travel at a certain speed. Very simple it is you will travel X00 yards at at X knots in three minutes. No math, no guessing, perfect for old Coasties and boaters! Of course this requires you to know your speed in Knots. A knot equals about 1.15 MPH.
As an example if you are traveling 7 Knots, you will travel 700 yards in three minutes. If you are traveling 4 Knots (other than being on a sail boat) you will travel 400 yards in three minutes. If you are traveling at 20 knots, you will go 2000 yards in three minutes (or one nautical mile). See no math just add two zeros to your speed (in Knots!) and you know how far you will travel in three minutes. Try it, pull out the calculator or nautical slide rule and try it as many times as you like. It works!
Don't think in miles on the water, think NAUTICAL miles. A nautical mile is 2000 yards, a little longer than a statue mile (5,280 compared to 6076.115, du to the curvature of the earth!). Which also happens to be one minute of LATITUDE. Latitude is the north/South component of Latitude and Longitude. This would mean that can use LATITUDE to measure distance. Pull out chart of Oneida Lake and take look. Latitude (N/S) is on the side of the chart, longitude (E/W) runs along the top and bottom. If you use the yard scale on the chart, you find 2000 yards equals one minute of latitude equals one natural mile!
Now what to do with all this knowledge?
You are traveling along the canal and the next lock is 7 nautical miles (NM) away. You want to get there in 30 minutes. Its 1015 in the morning. How many knots do you have to make have to get there? How many yards is it to the lock? Can you do this in your head?