How did sailors measure speed before electronics?

Three years ago Apparently it was only a little over a year ago that I discovered a wonderful tool to measure ship speed, a chip log.  It answered the question, how did people measure ship speed before the invention of technology.  Taking the idea, we set about making our own chip log craft for our homeschool history lessons last fall.

A word of warning to any parent planning to make this.  Before it is created, set hard and fast rules about swinging your chip log craft around.  Just to forestall any…….. accidental hitting your sibling in the head moments.

Not that THAT ever happened in my house when an over-enthusiastic boy might have done that.

Nope, not at all.

What is a chip log, and how does it work?

A chip log was a rope tied around a piece of wood.  The rope was then knotted at regular intervals for measuring.

Well, Claire does a great job of giving you super in detail information over at Angellicscalliwags that I linked to up at the top.  I’ll give you a quick summary, but they counted the knots as it unwound over a set period of time.

I’ll add, this is why ships sail at knots.

Sailors also had a similar device for creating soundings.  While you wanted a chip log to float, to make it easier to reel back in, and keep an eye out for.  A sounding rope you wanted to sink, and sink fast.  So it was attached to a piece of metal.

Fun bit of trivia

A sounding rope is also tied on regular intervals, and when the depth was between knots, the soundsman would cry out, “Mark ‘twain!”  Samuel Clemens, aka Mark Twain, was once a river man on the Mississippi, and would sound the depths, and that is where he got his pen name of Mark Twain.  I have always found that amusing.

Making our chip log craft

We modified Claire’s craft slightly because I have lots of empty spools of thread lying around.  We threaded yarn through the empty spindle of the spool, tied a knot, and then I had the kids set about tying knots every foot.  To keep up more or less on track, the knots were measured against our tile floor.  If we’d had bigger tiles, or a different convenient measuring tool, I would have used a further distance.

It really is that simple to make.  We then set about measuring the speed of the H.M.S. balcony, and discovered I balcony moves very fast for being absolutely stock still.

This year as part of our colonial America studies we attempted to make hour glasses.  I will tell you that is a ridiculously complicated craft, and it was very messy.  You’ll notice I did no list an hour glass as one of the crafts in this unit.  There’s a reason for that.

Check back tomorrow, now that we know our speed, we need to know just how where it is we’re speeding away to.