Here's a way to eyeball and estimate your speed in water, as I think there's a lot of seat of the pants guessing going on in general.. not you particularly, Dave.
There's 3600 seconds in an hour. 5280 feet in a mile. 5280 divided by 3600 = 1.46
that means you travel about one and a half feet in a second for every 1 mph of speed. So two or three mph is really hooking it up.
Got the 3600 figure from a highway patrol during a speedometer accuracy discussion. Drive any steady speed between two mile markers while counting the seconds. Divide the seconds into 3600. That is your speed.
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