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Determining Position East or West of the Reference Course
The reference course which runs between the point of departure and the destination (see
Course Strategy and Departure
Time)
serves as a local 0 degree longitude line against which the wayfinder
can keep track of his east-west position. During the voyage, the wind
will either allow the canoe to sail along the reference course, or what
is more likely, the wind will push the canoe off the reference course.
Thus the canoe is either on the course line (0), or a certain number of
miles to the east or west of it. When the wind pushes the canoe off the
reference course, the wayfinder must keep track of how far off he is.
Nainoa Thompson keeps track of deviation from the reference course in
units called houses. If the canoe goes one sailing day in a direction
one house to the west of the direction of the reference course, the
canoe is one house to the west of the reference course; if, on the next
day, the canoe goes one sailing day in a direction three houses to the
east of the reference course, it would be two house to the east of the
reference course. The houses east or west of the reference course are
distances (not to be confused with directional houses) and can be
translated into miles using a trigonometric formula for right
triangles, given the distance of one leg (one sailing day = 120 miles)
and one angle (one house = 11.25 degrees):
If the wayfinder loses track of his position in relationship to his
reference course (e.g., during a prolonged storm or in prolonged cloudy
conditions), he is lost; he can determine his north-south position
(latitude) through observations of the stars, but he can't determine
know how far east or west he is along that latitude. He remains lost
until some landfall (or seamark) allows him to determine his location
and reorient himself. When lost, the wayfinder can look for land by
tacking back and forth across an area where he thinks his destination
or some other island might be located.
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