Estimating The Speed of the Canoe
The speed of the canoe depends on the heading of the canoe and the strength of the wind and direction of the seas. Speed will be greater if the canoe is sailing on a beam reach (wind coming from the side); less if the canoe is close-hauled or going downwind. Hokule'a can sail up to 10-12 knots on a beam reach in strong winds (30 knots), with a following sea.
An experienced sailor can estimated how fast his vessel is going by the feel of the wind and the vessel and by watching how fast the water is moving past the canoe. A general estimate for the speed of a double-hulled sailing canoes is 1/3 the speed of the wind on a beam reach. In 10-20 knots of wind, a canoe can make about 5 knots, or 1/3 of the average 15 knots).
One can determine the speed of the canoe mathematically by timing marks (bubbles or objects in the water) moving past two points on the canoe. On Eala one can time marks moving between the front and back of the canoe, a distance of 45 feet; on Høküleça, between the front and back çiako (crossbeam), a distance of 42 feet.
A simple estimate can be made by dividing the seconds it takes for an object to go 42-45 ft. into 25.
25 ÷ 3 seconds = 8.3 knots
25 ÷ 4 seconds = 6.24 knots
25 ÷ 5 seconds = 5 knots
25 ÷ 6 seconds = 4.2 knots
25 ÷ 7 seconds = 3.6 knots
25 ÷ 8 seconds = 3.1 knots
25 ÷ 9 seconds = 2.8 knots
25 ÷ 10 seconds =2.5 knots
The mathematical formula for speed in knots is: Distance (converted to nautical miles) ÷ time (converted to hours) = Knots (nautical miles per hour)
Thus if an object moves 45 feet in 3 seconds
1. convert feet to nautical miles: 45 feet = .0074 nautical miles (45 divided by 6077 feet per nautical mile).
2. convert the seconds into hours: 3 seconds = .0008 hours (3 divided by 3600 seconds per hour).
3. divide the distance (.0074 nautical miles) by the time (.0008 hours)
to get the speed (9.25 knots).