Hōkūleʻa Update | Navigation Basics
As we make our way down south, our navigation team is using this time on board to “dial in” their navigation techniques. This includes the way we explain the concepts and skills we have learned and continue to learn; through teaching, one sharpens the learning. While everything that we discuss below can be found on the website, on this leg of the journey we are writing in great detail and sending back regular navigation iPad updates so that those who are interested can get a deeper look into the art and science of non-instrument navigation.
Navigation at its simplest is about observation of your environment, and making sense of that environment to give you clues about where you are and where you are going. More than a thousand years ago, canoes like this one were used to settle almost every inhabitable landmass all through the Pacific, an area covering more than 10 million square miles. Simply put, water was seen as a way of connecting islands rather than separating them. This was done in a time before metal was used in this region, and before the magnetic compass was used as well. But what these early voyagers cultivated and utilized was a very powerful sense of observation; that, coupled with an oral tradition that allowed those observations to compound generation upon generation, made for a robust information set over time. The system of wayfinding that the navigation team is using today been in consistent practice, unbroken over the generations, in some of the more remote corners of the Pacific like Micronesia. Pwo navigator Pius Mau Piailug from the island of Satawal in Micronesia brought this system to Hawaiʻi in the 1970’s, where it was modified into what is taught by Pwo Navigator Nainoa Thompson to students like those who make up the navigation team on this current leg.
It gets very complicated in practice, but at its essence, the navigation system answers two basic questions: 1) How fast are you going?, and 2) In what direction are you going?
How fast are we going? Seems like a simple enough question – that equation we were taught in our math classes in school, D=RxT or Distance = Rate x Time. We start first with time, which is pretty simple using natural cues. For our purposes, we estimate on this leg that sunrise is 6am and sunset is 6pm, or 12 hours apart. Our navigators track distance covered every 12 hours, calculating their estimates of total mileage traveled in 12 hours between sunrise and sunset, and sunset and sunrise. They do break down the day into smaller units of time, which they will get into over the next few days as they discuss the navigation strategies they use.
Rate or speed is a little more esoteric. A while back, someone figured out that if you count the number seconds it takes for something to travel between the first ‘iako (crossbeam) on the canoe and the last, and divide 25 by that number of seconds, you get speed of the canoe in knots (kts) or nautical miles per hour.
For example, if you throw a watermelon rind or orange peel into the water at the first ‘iako and you count 5 seconds to reach the back ‘iako, the canoe is travelling at 25/5 = 5 kts. If your count takes less time for that peel to get to the last cross beam, then naturally you would estimate that the canoe is going faster. Here’s the rough table we use to calculate speed, using the seconds it takes for an object to pass from front to back ʻiako:
3 seconds is about 8 kts
4 seconds is about 6 kts
5 seconds is about 5 kts
6 seconds is about 4 kts
8 seconds is about 3 kts
This speed check is done constantly so that different speeds (and thus, distance traveled) can be calculated across different hours as the day or night wears on. Every 12 hours we estimate the distance, and combined with the previous distance estimations, that gets us a total distance travelled over the course of however many days we have traveled. If we travel at 5 kts for the entire period from sunset to sunrise, we calculate 5 kts x 12 hours = 60 miles. In general, we find that Hōkūleʻa averages about 120 miles a day, or about 5 kts.
For the next question – In what direction did we go when we travelled all those miles? – we use the Hawaiian star compass that has become a familiar image to so many.
The fundamental design of this compass is thousands of years old. Nainoa learned the compass from Mau, and from that the Hawaiian star compass evolved during Nainoa’s training for the 1980 voyage to Tahiti. It is a 32-point compass in which stars, wind and waves are used to determine direction. The four cardinal points; ʻĀkau (North), Hema (South), Hikina (East) and Komohana (West) anchor the corners of the compass. Each of the seven sections or houses are named the following: Lā, ‘Āina, Noio, Manu, Nālani, Nā Leo and Haka. If you look at the graphic, these houses radiate out from east and west and fan towards north and south as mirrors of each other in the four quadrants. To distinguish amongst repetitive houses, each quadrant is named as well; Koʻolau, Kona, Malanai and Hoʻolua, for the general main winds that we see in Hawaiʻi.
On Hōkūleʻa, we imagine the canoe is in the center of the compass, and the star compass itself is overlaid on the canoe by marking the 32 houses along the railings, radiating from the navigator’s perch in the back corner of the canoe. The canoe is depicted in the star compass graphic by the ʻIwa bird. To reference the direction that the canoe is heading, the navigator will stand in the back corner of the canoe where the beam is lashed to the rails and identify which houses the stars, moon, sun, swells, etc. are rising or setting in. For example, on this sail down to Rapa Nui, we have the constellation Orion setting in the west off of our starboard beam (e.g. the right side of the canoe). The star Mintaka, which is the bottom star in Orion’s belt when it’s setting, sets due west; given this known point, we can then orient the canoe to the star and use the markings along the rail to set a southerly course towards Rapa Nui.
So far it’s been about a week out at sea, and we’ve experienced nearly complete cloud coverage each night, as well as a big moon that masks the light of the stars. Bright stars like those in Orion, Aʻa (Sirius), the Southern Cross, and the planets have been a blessing when they are visible, but their appearance is often short-lived, challenging the navigators to quickly identify the celestial bodies and recalibrate their direction.
We’ll continue to blog about the navigation fundamentals, challenges, and learning opportunities as we continue on our course line towards Rapa Nui. Please check out our live tracking map; these navigation deep-dives should bring what you see to life. Stay tuned for more updates and information from the crew of Leg 28 of the Worldwide Voyage.
We’ll be Standing By 72,
Haunani, Jason and Nāʻālehu
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