history,  homeschooling

Henry Hudson, 17th Century Navigation and my homeschooling children

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I’ve been reading Half Moon: Henry Hudson and the Voyage that Redrew the Map of the New World and God’s Mercies: Rivalry, Betrayal and the Dream of Discovery, both by Douglas Hunter, and while this is my interest not the children’s, I wanted to share parts of it with them. Without planning ahead, but just exploring different details as we go along, we came up with the following little “unit study.”

How do the old North-by-Northeast compare with modern compass points?Learning about 17th century navigational techniques seemed like a logical first step. We’ve learned before how to use an astrolabe, and now we learn that Henry Hudson used an older cross staff despite the invention of a more accurate backstaff. So this provided an excuse to review how the astralobe works like and to learn about the cross and backstaffs.

We put regular knots in a rope and dropped it from the top of the bunk bed to establish the depth to the bottom of the ocean. We used one foot divisions but talked about how the fathom was, at one point, approximately six feet deep. (Quick math question: how many feet is 40 fathoms deep?)

We made a little lego spool to release string to measure the speed we’re travelling and talked about how it would appear like the chip is moving past the boat when really it would be the boat moving past the chip – unless of course your boat is a bunkbed, in which case it really is the chip moving past the boat.

Learning about 17th century navigation with a traverse board.I printed out a traverse board and stuck it to a bulletin board so we could use tacks instead of wooden pegs for recording distance and direction. I challenged my eight year old to mark on the 32 compass point drawing the comparable number of degrees. Using a protractor he figured it was 10 degrees between each point, but then realized that East would be 80 degrees, whereas he knows its really 90. So then he had to divide the 90 degrees in half to figure out what North-East is. Then half of the distance to North-East is marked by North-North East, and half the distance between North-East and East is marked as East North East. Then the spaces between all of those is divided in half and marked in. The distance between the two neighboring points is 11 1/4 degrees. It was a good lesson in using logic instead of approximate measurements with potentially incorrect tools. Of course 17th century explorers frequently had inaccurate tools. What would happen if their knotted measurement ropes were a little bit stretchy?

I gave directions for a route a ship might take, switching the speed and direction and getting my eight year old son to mark it down on the traverse board and then to draw the route out on a sheet of paper carefully measuring the distance and angle sailed and then figuring out how long and in what direction a person would have to sail to get to the same place in one long line instead of a swerving course.

The kids could invent stories and draw their own maps. My five year old could practice his writing labeling his map. There’s lots of room for imagination and play.


The book Half Moon, and God’s Destiny talk about mutiny being an incredible risk. Once when Hudson was up trying to find the Northeast passage he sent every last crew member except his son to go Walrus hunting, possibly because he couldn’t afford to send the crewmen he trusted and risk being overwhelmed and losing his ship. He brought a certain Henry Greene onboard his fourth and final trip probably as a spy to report any fractions among the crew. Yet at that time mutiny wasn’t a specific crime in English law, only piracy or the taking of a ship for piracy. Still for the portion of the crew that made it back to England after abandoning Henry Hudson and eight others in the shallop, hanging would be the obvious result. Except it wasn’t, because the crew were too important. They were the ones with knowledge of the great open space beyond the Furious Overfalls (now the Hudson’s Bay, beyond the Hudson’s Straight) and that made them too important to hang, so their argument that the institutors of the mutiny had all died on the way home was accepted. You have to wonder what it would feel like to be the Captain of the next ship they were sent out aboard!
It sounds like his second crew was scared of being criticized for putting pressure on him, for Henry Hudson signed a paper for them saying that they were turning back for home by his decision and not under any pressure from them. His third journey was for a Dutch company, in a ship with only four Englishmen on board (Henry Hudson, his son and two others). In that case Hudson and the crew appear to have stolen the ship going not where the Dutch sent them (to look for a Northeast passage) but along the coast of the New World. Hudson may have had information from his acquaintance John Smith, and appears to have wanted to explore rivers near the struggling Jamestown. The trip there involved a little detour as they chased another ship quite possibly with the intent of piracy. The returned to Dartmouth rather than Amsterdam, probably for fear of what their employers would do to them, and Hudson told the Dutch consul in London that the crew had wanted to overwinter in Newfoundland but that Hudson had resisted because he was scared they would run out of food (and probably turn to piracy). He avoided having to return to Amsterdam to face his employers by being “arrested” by the British who felt his privileged knowledge of the new world was a matter of national security they were unwilling to part with.
Henry Hudson believed that there was a temperate area in the North. The logic was that the long, long day would heat the arctic like a small fire burning constantly instead of a large fire burning periodically. This belief was partly practical. Like other explorers of his time he needed to justify his expenses to his investors and the idea that there was a temperate area further North encouraged the belief that the could be a Northwest or Northeast passage. His ship’s journals apparently included mentions of being warm at Northern islands.
Hudson’s belief in the temperate North was also justified by his misunderstanding of the origins of sea ice. He didn’t understand how salt precipitates out of water when it freezes so the apparent lack of salt in sea ice was taken as a sign the ice came from frozen rivers that floated north rather than frozen ocean. So we had to look up some experiments about salinity and sea ice.
I think one of the things that fascinates me about the period is the idea of being on the brink of understanding something but yet making so many mistakes. There was hope and excitement, and yet it is all so crazy too. The maps they drew were wildly inaccurate. Islands would be identified and remain on maps for ages and ages yet never actually exist. Henry Hudson described members of his crew seeing mermaids. They were starting to realize there was some sort of inaccuracy with their compasses but they hadn’t figured out yet that magnetic north and true north were in different places. The willingness of the explorers to fudge details or outright lie in order to get investers to send them to sea again makes me laugh. Is it any different from today? I think of researchers making very legitimate, very worthwhile contributions to science who nevertheless have to exaggerate their work and claim to be on the brink of curing cancer simply to get funding as well as those whose “science” is total nonsense.
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