A canoe approaching an island against the direction of the swell will, when it is dead on course, encounter the wave collision point, the foam line in the sea. As the canoe comes from a zone of swell, the bow of the canoe will rock stronger than its stern. The canoe will then enter the quiet water area. All that needs to be done, is to ensure that the canoe will stay in the quiet water area and the canoe will reach the island. If the canoe approaching the island is not dead on target, it will encounter an area where the swell is crossed by refracted waves, and where both waves can be felt clearly. The stronger of the two waves, with the greater time interval is the swell, while the weaker wave with the slightly shorter interval is the refracted wave. The navigator needs to steer the canoe in the direction where the refracted wave comes from and will eventually reach the island. If the approaching canoe is so far off island that the refracted waves cannot be felt, the island will be missed.
A canoe approaching the island with the swell will encounter the zone of the reflected swell if it is dead on course. Again, the navigator needs to keep the canoe with the triangle of the reflected waves in order to reach the island. The deflection pattern of the waves on the swell-ward side of the island is similar to the refraction pattern on the leeward side. If such a deflected wave is encountered, the canoe needs to be steered in the direction the wave came from in order to reach the island.
If the approach to the island is neither with nor against the swell, but at right angles to swell, then the navigation has to look out for the refracted waves coming from the island. As before, the steering needs to be done into the refracted or reflected waves. Care needs to be taken to keep the canoe within the area of the reflected or refracted waves.
The pattern becomes more complicated if we consider more than one island or atoll. While each of the islands has an approach or departure pattern very much like the one described above, there is the distance between these two approach systems, which needs to be covered.
Source:
- Spennemann, Dirk H.R. (1998). Essays on the Marshallese Past Second edition. Albury: URL: http://marshall.csu.edu.au/Marshalls/html/essays/es-tmc-2.html