All in a tangle

That's pretty much how I felt after doing just a little research on the subject of ropes & cordage.  Hopefully what I have distilled from aforesaid research is going to be of some help to you.  If not wander aft sit yourself down put your feet up and get a glass of something else that's been distilled.  Better yet read on with your tumbler full.

The earliest recorded use of rope is around 4000 B.C. in Egypt.  And when you consider that along the banks of the Nile with miles and miles of perfect rope making material and just a few miles away one of the finest sailing waters it comes as no surprise that they would have.  Then again they had some pretty big building projects on the go and some fancy plaiting of reeds would be of huge benefit.

All sorts of materials were used for making ropes.  For example:  Grass, leather, hair and reeds.  The Egyptians used plaited reeds to haul huge stones for the pyramids and possibly used it also to encourage the haulers - ouch!

The Chinese, ever the clever, discovered hemp.  And along with their great sailing vessels made good rope.  If you consider how much rope was used on the average Chinese Lug (Junk) it's not surprising that they found a better material than hair to use.

Most ropes today of course are synthetic.  The most common form of making them though is still the twisted rope or laid rope.  Essentially 3 'sub-ropes' twisted together to make the main rope.  The twist usually going from left to right.  That's why it's best to coil a laid rope from left to right (clockwise).  That way we don't get no kinks.

If a stronger rope is required and it's a twisted rope that is preferred it could have four or more strands.  A four strand rope is known as a shroud-laid rope.  My guess is because this kind of rope was used for shrouds (before steel cable).  For even stronger rope more strands were used and that is called cable-laid rope.  No prizes for knowing why.

Twisted ropes are literally bundles of yarn twisted together to form 3 strands which in turn are twisted together to form the final product.  It's in the twisting that the rope gets it's strength and resistance to unraveling.  Twisted ropes, due to the ease of manufacture, are generally less expensive than braided ropes. They are also much easier to splice.

Braided ropes are manufactured with a number of braiding patterns, but all of them are made up of bundles of fiber which make up the strands used to make up the final product.  By interlacing (plaiting) in various ways the rope has differing properties and therefore suited to different applications.  A regular cored and braided rope is round and well suited for use as a halyard or sheet where roundness is vital for turning over pulleys or winches.

The strength of these ropes lies in the inner core which is protected by the outer braided cover.  This braiding when in a diamond shape for example tends to be flatter and is not as strong as other patterns.  The core in the diamond braid prevents the flatness.

Double braided rope is basically one braided rope inside another.  The inner and outer ropes are designed to share the loading evenly and due to this construction are very flexible, strong and easy to handle.  Splicing of these lines are easy.  The major drawback is that the outer sheath can slide along the inner and cause bunching up (milking).  When this happens the inner rope takes most if not all of the strain and as you can imagine substantially reduces the strength of the rope.

The inner workings

There are essentially two types of materials used in rope manufacture:

1.  Synthetic
2.  Natural

For durability and strength synthetic fibers far outweigh the natural.  Although I believe, on a strength to weight ratio, there is nothing to beat the spider's own rope making skills.

Of course wear and tear is by far the biggest killer of rope but the harsh UV in tropical regions has a lot to answer for when it comes to rendering rope useless,  Polypropylene being the most susceptible.  But the materials used today to make ropes have by and large been treated or constructed with stabilizers to protect them against UV and chemicals.

The all round common fiber used is nylon.  Being a strong material as well as durable.  Great for the marine environment but moisture does weaken nylon.  Nylon is hygroscopic (absorbs water) and therefore over time the structure of the material will change and weaken.  The great advantage of nylon is that it handles shock loading very well due to it's 'stretch-ability'.

Polyester is much like nylon but does not stretch as readily and therefore less capable of withstanding shock loads.  As in the case of nylon polyester does not rot or mildew.  Unlike nylon though polyester is impervious to water and therefore will not weaken this way.

Polypropylene is the cheapest of the common synthetic rope fibers.  It's light and therefore it floats.  This is a great asset for towing for example (light towing that is).  If you are nervous of tangling your line around your prop when maneuvering to throw a line…polypropylene is a good choice.  For mooring lines and springs it is great too (nice and stretchy) with one proviso!!!  Not a good idea for permanent moorings.  Polypropylene degrades in sunlight faster than you think.   It wont be long before the outer layers of this rope starts to chalk and get 'spiky'…tell tale for UV degradation.

Poly-steel.  This material is a co-polymer of polyethylene and polypropylene.  It's a lot stronger than polypropylene and therefore is a better alternative.

Nylon and polyester ropes have an approximate 10 year shelf life.

Kevlar.  The super-fiber of the 20th century next to carbon fiber.  It don't stretch nor creep and can handle just about any temperature thrown at it.  So what is it's big drawback?  It can't handle shock loads very well.  Neither is it comfortable in the tropics (UV resistance is very low), radiation and abrasion.  To counter all these negatives Kevlar forms the core of ropes with a sheath of material better able to withstand the elements etc.  One last thing about Kevlar….Kevlar rope does not like tight corners nor being knotted.  It's a tough life!

Spectra.  Very light but not good on the melting point.  In short - it floats but no good for the central heating.  You can give it a shock though…works really great in the shock loading department.  But being a slippery material also does not take kindly to being knotted.  Spectra though can be rubbed up the wrong way so takes to abrasion very well.

Spectra is a brand name.  Other brands are Dyneema, Nomex, Twaron, Zylon and a few others.  Essentially these products use the same base materials in their manufacture.

Cotton.  If someone could figure out how to stop cotton from rotting through moisture we would have a great material for rope.  Being a natural fibre it has everything going for it in the environmental stakes.  It's soft so handles well,  loves being knotted and altogether a good rope.  What would you expect from nature?

Manila.  The strongest of natural fibers which are from the banana plant family.  Don't store well though.  In the marine environment where moisture is a constant problem Manila rope will not last.  In their favour manila does not stretch and takes knots without significant weakening.

Hemp.  It works but not on the water.  Not a strong fiber at all really and when wet is even worse.  Old hemp rope could be used for a tugs fenders.  Not Perseus!!

How to look after your rope.

What destroys rope really quickly is the grit that gets in between the fibers.  Acting like microscopic saws they cut away at the fibres until one day 'TWANG!'  You find yourself adrift.  If no one is around to see you do it…send the laundry guy to the movies or a night on the town…you can use the washing machine with a small amount of MILD detergent.  Failing that a bucket and scrubbing brush will do the trick.  One thing I do know that works if you have the time and is safe to do…..trail your line overboard for awhile.  Either let over the side in one long line or in a net bag.  Afterwards rinse off the salt with fresh water though.  When you dry the rope keep it out of bright sunlight.

Other than that the common sense stuff applies.  Always coil your ropes and stow away.  A tidy ship is a happy ship and more importantly a safe ship.  If the rope is not in use do not leave in the blazing sun.  A cool dry place will add years to the life of your cordage.  Lastly, keep the ends whipped, heat sealed or spliced.  There is nothing worse than a frayed rope end on board.

What effect does knotting a rope have?

Believe it or not (I resisted the temptation with the pun there) a knot reduces a ropes strength by as much as 50%.  The mechanics of this is not difficult to grasp.  In the heart of the knot all the fibers are forced beyond what they can bear.  The distortions and contortions the fibers undergo weaken the fibre quite considerably.  So for example a loop made using a bowline will be much weaker than a splice and both are weaker than a swage fitting.  So when using lines for moorings etc consider using swages rather than trusting long term knots.