Navigation and stick charts: Part 1 – Navigation

Historically, Marshallese were considered among the best navigators in the Pacific. They had to be as the atolls they sailed between were great distances apart and much of the sailing was on open ocean where no land could be seen. Once canoes were 10 miles from atolls the highest point (coconut trees) of low lying atolls were no longer visible. To navigate the Marshallese primarily utilized 2 systems: 1) celestial navigation (stars, sun and moon) and 2) wave pattern navigation. The development of wave pattern navigation is fairly unique among the Marshallese and is the basis for much of their successful navigation and the rest of this essay.

Wave pattern navigation is based on the principle of reflection, deflection and refraction of waves. These effects of islands on swells may be noticed more than 20 miles away. To understand wave pattern navigation, first consider a single, isolated island or atoll. If waves hit a stable object, such as an island, some waves are reflected, that is mirrored back into the direction from which they came (figure 1a). Others are deflected, sent back at a different angle, at the margins of the island or atoll (figure 1b). In addition, each island creates a conical shaped zone of quiet water on the leeward side of the atoll, where the swell cannot reach (figure 1c). The dimensions of this quiet water area depend almost entirely on the dimensions of the island or atoll blocking the path of the swell. Further out on the leeward side of the island there will be a zone where the refracted waves (figure 1d), coming from both sides of the island, will meet (figure 1e). This area is defined by waves coming from two directions and colliding, creating a foamy line on the ocean. These waves will then continue out from this point until they become to weak and fade away (figure 1f).

Figure 1. Principles of Wave Pattern Navigation. From http://marshall.csu.edu.au/Marshalls/html/essays/es-tmc-2.html 

Wave pattern navigation works best when there is there is a sufficient number of atolls or islands that are close enough and run perpendicular to an ocean swell. The Ralik and Ratak chains of the Marshall Islands meet this criteria as they run NNW to SSE and are close to the perpendicular east and west swells. In the Pacific Ocean, the Marshall islands are one of the few island groups that meets this perpendicular requirement and thus makes wave patterns useful tool for navigation.

Learning wave pattern navigation was difficult and in the past only a few Marshallese were taught the secrets of sailing and navigation. These trained navigators were called ri-meto. In order to become a ri-meto, an apprentice had to be trained by a senior ri-meto and this would often take years. The apprentice then had to pass a voyaging test, devised by his chief, on the first try. It is said that these skilled navigators could lie on their backs in the bottom of their canoe and without looking at the sea, sense the motion of the swells on the canoe and use this to navigate. Over the years, especially after WWII contemporary navigation (e.g. maps, GPS) methods have replaced traditional Marshallese ones and the number or ri-metos has diminished and the last well-known one died in 2003. (NY Times, 2016). Also, few tipnols (sailing canoe) and walaps (large sailing canoe) exist and because of this sailing between atolls has become rare.

For more detailed examples of how to navigate to an island using the above principles – try this link Navigation 2

References