This video shows how to use 'Dutchman's Log', an iOS and Android app to measure your boat speed through the water. It can also be used to calibrate your boat's log instrument.
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A boat's speed may be estimated by timing how long it takes to pass a floating object.
Set boat length and desired units in 'Settings'.
Two persons are needed: one stands on the bow, and the other aft.
The person on the bow throws an object that will float (eg crumpled piece of paper) into the water, ahead and to one side of the bow.
As it passes the bow at right angles, they shout 'Now', and the person on the stern starts the digital timer.
When the object passes the stern at right angles, the timer is stopped.
The App now calculates and displays the boat speed.
