I was at a friends house, and his maritime obsessed parents had a display case of various knots used on ships. Many of the knots seemed very complex, and as my friends dad explained to me, many of the knots are either wet or dry knots. I was curious to know if there is a history of the various knots and how they came to be. For example, was there some kind of boating accident that happened because of a certain knot, and a new knot was required? Or is there some knot genius comparable to Pythagoras making geometry? Are the knots used on ships the same in other countries?
I'm sure that there will be several texts published on maritime knots. The yachting fraternity, and others who wish to be associated with such people appear to be almost obsessed with knots of various kinds, which is why one finds knot "displays" for want of a better expression, on sale in various yacht chandlers and other seaside emporiums. Many knots have particular purposes, and are particularly suited to particular tasks, and many have their job, as it were, incorporated into their names.
Here are a selection: The Reef Knot is a simple knot for tying together two ropes of equal thickness, and was used to tie the reefing points on sails as it is a knot that is quick to do and quick to undo. The Sheetbend is used to tie together ropes of unequal thickness, and was used to secure a "sheet", the rope that controlled the leech of a sail. A Heaving Line Bend is usually made around a metal weight at the end of a rope that one wishes to use as a heaving line, this gives weight to the end of the line, so that it is easy to throw to the intended recipient.
Others have names that are descriptive if their purpose. A wall knot is made to tie of and secure the strands at the end of a rope to prevent it from fraying. A crown knot is an extension of the wall knot to round it off and make it look neat. It is usually used at the end of a manrope both to give it a neat appearance as well (as to prevent it fraying) and to provide something to grab hold of if necessary.
Others are named after what they look like. A "Turk's Head" because it looks a bit like a turban, for example.
As far as I know they are pretty much universal, but very few, beyond those I've described, are ever used on ships. Others that I've heard of being used, (and was forced to learn to do) but very rarely, are the Matthew Walker and the Carrick Bend.
There are those who are interested in knots for their own sake, but they have nothing to do with actual maritime practise, and are more in the way of people who like maritime things, without fully understanding them, but who don't realise that they don't actually understand the reality.