How did sailors navigate before the age of GPS?

In 2016, if I need to know how to get somewhere I will type the destination into my phone and it will tell me step by step how to get there.  But, how did sailors navigate before GPS?  Did they just point a direction and go?  Of course not, they had all sorts of ideas, in the Age of Exploration they used portolan navigation which led to a delightful homeschool history lesson with a bit of homeschool math snuck in as we worked on a form of charting and graphing (oh and some homeschool geography because we did this activity as part of our revisit of the country of Portugal).

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Portolan Navigation

Portolan navigation came about because sailors were now leaving sight of the land.  That’s a scary thought if you’re not entirely sure how to get back.  Our earliest known use of them is in the 13th century (1200s), but they became particularly well known under Prince Henry the Navigator (who you’ll learn more about in a few weeks).

Portolan navigation is originally based off of the compass rose, and triangulation points.  In the Portuguese model, portolan navigation is somewhat more triangular, but still based off of the compass rose.

Simulating portolan navigation

We used an activity from Mapping the World with Art*, which has quite a comprehensive chapter on Prince Henry the Navigator, and shares quite a bit of information on him.  Thankfully she had the printable pages on her site, because I misplaced my CD for printing stuff.

The instructions on her activity called for you to draw out the lines on a poster board, and if I were doing this with a class I would do that for sure, but for the purposes of being lazy I just printed off her sample portolan map and had the kids navigate on that.

Additional supplies needed: something to be your 3 ships (we used Legos because let’s face it I have a lot of Legos in my house), pencils to mark ending lines

Rules we used:

1. You may not mark out your route.  The explorers did not have that option, so you may only consult the map and move on from there.
2. No touching the other person’s ship.  If it blocks your path, you may not complete your path.
3. When you have completed your path, write your initial on the spot and take your ship off.

In addition I should have moved their navigational portolan map further away to make it more challenging.  I think since the map was the same size as their navigational field it made the activity easier.

Then the kids set forth on their journey.  I had marked the Legos with a small dot to mark the front of the ship.  They were required to keep that part facing forward at all times (because ships don’t sail backwards).

What we learned from our Portolan navigation

The kids all wondered why the ships had such weird sailing patterns.  So we took a minute (literally, I filmed it) and had them brainstorm why they might have had such erratic patterns.

 

Trying out portolan steering. It’s harder than it looks.

A video posted by Ticia (@ticiam) on Oct 7, 2016 at 12:39pm PDT

Here’s our thoughts:

1. Islands that might have been drawn on the map, but not on our navigational charts
2. Shallow water their ships couldn’t go through
3. Currents that might be going the wrong way
4. Shoals (which I think are just shallow water, but with dangerous rocks)

All in all, it was a fun attempt to navigate as the sailors did back then.

Check out the rest of our Life of a Sailor series.