|
Compensating for Leeway in the Canoe's Heading
When
a canoe is sailing with the wind forward of its beam, its
actual heading is not the same as its apparent heading because it is
being pushed off its course by the wind. The angle between the apparent
heading of the canoe and the direction the canoe is actually traveling
through the water is referred to as leeway. This angle may vary from
4-15 degrees to leeward, depending on (1) the strength of the wind; (2)
the angle the canoe is sailing into the wind (the greater the angle,
the greater the leeway); (3) the draft of the canoe (deep-keeled boats
have a smaller leeway than shallow-keeled boats); (4) the speed of the
canoe (the greater the speed, the less the leeway).
The wayfinder must compensate for leeway by pointing the canoe more
sharply into the wind, or if the canoe is pointed as far as possible
into the wind as it can go, he subtracts leeway to determine his course
made good, or actual heading. For example, when the wayfinder wants to
go in the direction of Manu Malanai (SE) and the wind and current is
pushing the canoe one house further south (toward Nalani Malanai, or SE
by S), the wayfinder must point the canoe one house further north
(toward Noio Malanai or SE by E) to make good his direction of Manu
Malanai; if he cannot point the canoe any farther into the wind, then
his course made good is actually Nalani Malanai (SE by S), rather than
its heading of Manu Malanai (SE).
The wayfinder can calculate the amount of leeway he must compensate for
in his heading by observing the wake of the canoe in relationship to
the direction of the canoe. The angle between the direction of the
canoe and the wake behind the canoe tells the wayfinder how much
sideways displacement there is due to the wind. Another method, if it
is practical, would be to attach a line near the center of the sail
effort of the canoe and to calculate the angle of this line from the
centerline of the canoe. An experienced
wayfinder, knowing well the capabilities of his canoe, will be able to
estimate leeway given the direction of his heading and the speed of the
wind working against the canoe
|
