Sailboats use a lot of rope. There’s rope for rigging, rope for halyards, rope for running rigging, rope for anchor rodes, etc etc ad nauseum. Before I delve into some of the details of rope, I must make one little definition. Rope is the stuff before it’s installed in its functional place on board, i.e. raw material. Once the rope is installed as a jib sheet or a halyard it is referred to as a line. So if it’s used for docking it’s a ‘bow line’ or a ‘stern line’ or a ‘spring line’. There are a few ‘ropes’ on a boat. There’s the ‘bolt rope’, which is the rope that goes around the edge of a sail (not something you have to remember unless you’re sewing sails, usually), a tiller rope (to secure the tiller when you walk away from it) and a foot rope (to slide your feet under when you’re leaning out over the gunnel or working a square rigger.) Anyway, rope is the material for making lines.
There are two basic kinds of rope designs: laid or twisted rope and braided.
Twisted rope is the stuff of salty splices and intricate arrr-matey-arrr ropework. Twisted rope is just that, twisted. I’m not talking about its need to talk with Dr Freud. I mean that as the rope is made the fibers are literally twisted from one end. When you put three of them together and twist the ends of all three they naturally twist together like snakes in a menage-a-trois. If you control the passion correctly they will lay alongside each other in spirals and that is ‘laid’ rope. You can actually make your own twisted rope from soft sea grass if you parallel two or three pieces together and twist from one end. Twisted or laid rope is made of all sorts of material from hemp (yes, from the ‘evil’ marijuana plant, even George Washington had it growing at Mount Vernon for making rope), nylon, dacron, manila, polypropylene, and sisal. The last two are horrible on your hands, so I wouldn’t use them for anything other than cheap anchor rodes for dinghies.
There are many types of braided line, but mainly there’s solid braid, hollow braid, kernmantle and marine braid (or braid on braid). Hollow braid is just that. When the braid is done it forms a rope tube, if you will, with nothing in the middle so it’s literally hollow. Solid braid is also just that, when the braid is complete it is a solid piece, like nylon line at the hardware store. Kernmantle is a combination form, which is a straight line core (the kern), covered and controlled by a braided tube (the mantle) on the outside. Parachute cord is of a sort of kernmantle construction. Kernmantle is used a lot for climbing applications, as it’s very strong and easily handled, but modern halyards and sheet lines are of the marine braid type, as it’s also strong and easily handled but also that it’s more easily spliced. Marine braid is a braided core with a braided mantle. Marine braid kinks less than laid line, so it’s easier to coil. Braided rope comes in all sorts of materials, nylon, dacron (and other polyesters) and the more exotic materials like Kevlar (which is wicked expensive, in my experience used only by the rich and shameless.)
Much discussion goes on about what design and material is superior for what application. Laid rope is easier to splice and is usually less expensive. Just stay away from cotton plow line for nautical applications, as it gets very stiff and recalcitrant when it gets wet.
So much for rope talk. I hope you don’t think I was feeding you a line about anything because it can be a knotty problem to string folks along. (Sorry, but I’m really tired, I had to do it.)