Thursday, October 7, 2010

Boats and ropes

I recently went to the Victoria Classic Wooden Boat Festival and snapped a few pictures of ropes, lines and cordage and how they are used on boats. It made me wonder what rope was, and what cordage was. Were they the same or was there a distinction? If you just look at twisted (spun) rope and forget plaited or braided rope (we need to keep sane here), is there any difference in spinning technique other than having a humongous spinning wheel? And what is the history of rope?

So here is my understanding... Oh, and by the way, rope isn't made with humongus spinning wheels, it is laid out in a long length and twisted from one end... First you have fibre. You spin fibre and you get yarn. If you spin the fibre to the right or clockwise, it has what is called a Z-twist or, in rope language if you look down a length of rope and the twist is to the right (Z), it is known as having a right hand lay; if the twist is to the left (S) it is a left hand lay. If you twist two (or more) Z-spun or right hand laid yarns together in the opposite direction, and spin/twist them S then you have a strand which is left hand laid. Take strands and twist them together (opposite twist than the strand) and you have rope. Got that? One more time:

  • Fibre spun Z = yarn
  • Yarns spun S = strands
  • Strands spun Z = rope
Now here is where we get all salty and nautical. A 3 strand rope is known as a hawser-laid rope.  A four-strand laid rope is called shroud-laid. And now if you take 3 or more ropes and twist them you get a cable.  A 3 strand rope is very flexible, easy to handle and good for making knots.  A 4 strand rope is firmer, rounder and hence good when you need more surface to grip, say going through a pulley.
Cordage is the term used for less than 3/8"diameter and rope for more than 3/8" diameter.  I suppose you can argue about the thickness but the idea is this: fibre, string, cord, rope, cable.
I came across an interesting video showing some recent history of rope making but for something about older technology check out the Native American Cordage web page.

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