潜伏者。如果你知道你的当前位置,土地的位置你ʻ走向,然后你只需要能够确定方向和跟踪你的进展(执行航迹推算)。可以确定方向的一些关键的恒星(东部和西部附近的日出和日落的方向和具体的方向取决于年)的时间。北极星总是北,Mintaka在猎户座ʻ年代从正东方正西方从地球上每一个纬度。其他恒星ʻ上升和设置点取决于你的纬度不同程度。大概你可以检查你的北极星高度纬度,北极星,北方地平线以上,或直立的南十字星的高度高于南部地平线。也有某些双恒星这一点几乎是垂直堆放时由于北或南。例如,天枢星和天璇垂直对齐的时候几乎是正上方。他们还充当指南找到北极星。ʻ如果你不知道你的位置,或者土地的位置,那么你需要某种指标的土地本身。 In the trade wind belts, there is often a stationary pile of clouds over high volcanic islands, whereas most cumulus clouds float freely downwind. It is alleged that clouds directly over coral atolls with central lagoons may sometimes reflect a green color from the lagoon. Seabirds such as the brown noddy and fairy tern that are known to sleep on land at night can be used to locate land, since they head out to sea in the morning to fish and fly back at night to sleep. That gets more complex when they make multiple fishing trips to feed their young. Lines of rubbish and organic matter (leaves, sticks) may indicate land is nearby. If you know the prevailing direction of the swells or can calibrate them with the rising or setting sun or recognizable star, swell directions typically donʻt change quickly in under 24 hours. If there are multiple swell patterns with the exact same period (time between swells), that may indicate that one of the swells is a reflection off of an island of the other swell, or a refraction of the original swell bent by the shallow water around an island. This was a mainly Marshallese island technique. They were noted for their wave pattern stick charts, which were apparently more used for studying and teaching than actual use during a voyage. We, The Navigators by David Lewis chronicles much of this.