Knots are used frequently with sailboats for many reasons. The qualities of a good knot are ease of tying, ease of untying, secure, strength, and either no slipping or controlled slipping. It is important to use the best knot for each purpose while on the sailboat and at the dock.
We start with the Bowline, my favorite and the knot I use the most. The bowline forms a loop in the end of a line that will not slip. It has so many uses, but most commonly to tie the end of a line to a fitting or block. When tied properly, the bowline can be used for years and still untied easily. CAUTION: Some new lines are stiff and slick and made not to tangle. These lines may not hold a knot well, which is how they're designed. With these lines it is better to use a Splicing Nut.
Bowline
Click the play button (maybe twice) to start the video.
Sheet Bend. The sheet bend is used to tie two lines together. It is the same knot as the bowline, not used to form a loop in the end of a line but to tie two ropes together. It can be used at the end of both lines, or the end of one line can be tied to the middle of the other line. Like the bowline, it does not slip and is easily untied.
Sheetbend
Click the play arrow (maybe twice), to see the video.
The Double Half Hitch is used to tie a loop that will slip in the end of a line. Unlike the bowline, which will not slip, the double half hitch forms a loop that will slip and tighten the loop when pulled on. It is an easy knot to tie and untie, and is useful for making the end of the line fast to something you can get the line around or through. Useful at times to tie your boat to a ring or post, and to tie the end of a line to many things. I don't find it as secure as a bowline, but handy nonetheless.
To tie the double half hitch, pass the line around something and tie a half hitch around the standing part of the line, and then in the same direction tie another half hitch. If you tie the second half hitch in the opposite direction as the first, you will have two half hitches, but not a Double Half hitch.
The Clove Hitch is most commonly used to tie a boat to a post we can pass the rope over the top of. It is easy to tie in the middle of a rope, which makes it very handy with long dock lines. The first turn is around the post and under the standing line going to the boat, just make a loop the proper direction and place it over the post. If you then make another loop the same way and place it over the post you have a clove hitch.
To untie we just lift it off the post, and there is no knot at all.
The Rolling Hitch is a quick and simple knot used to tie one rope to another line that may or may not be taut. It can also be used to form an adjustable loop in the end of a line, useful for many things. On sailboats it is used to tie to a jib sheet that has tangled on the winch to release the pressure while the sheet is untangled, as shown at the end of the video. Properly tied, it will not slip in the direction of pull, but can be pushed in either direction along the line.
The figure 8 is most often used to make a knot on the end of a line. This can prevent the end of the line from passing through a block or hole, keeping it ready for use. The double figure 8 can be used to tie two lines together with less strength loss than another knot, and the "mountain climbers" knot forms a loop somewhere in the middle of a line. Another variation is the "stopper knot", which has an extra round turn on one side of the figure 8 so it is a bit larger.
Figure 8, 14 MB
The Cleat Hitch is used to fasten a rope to a horn cleat. Always use a good nylon rope with stretch to tie your boat to something! When I worked at a marina one of the things I did was replace the cleats when a boat ripped them off the dock. Weekend motor boaters would sometimes tie their boats with a piece of ski rope, which has no stretch. When a boat came by and made a wake, their boat would go up and down, jerking on the rope. When a boat that weighed thousands of pounds would rise and fall, coming to an abrupt stop at the end of the rope, it would pull the cleat from the dock. Using a nylon rope with streach gives a little shock absorbtion, making the cleats hold better and the boat more secure. Sailors would sometimes tie their boat with an old piece of sheet or halyard, which also has little stretch and also bad. One Catalina 22 tied with an old sheet, ripped the bow cleat through the fiberglass.
Humans have used horn cleats for centuries, and we know how to tie a cleat hitch to fasten a rope to the cleat, but I still notice people inventing their own knots to fasten to a horn cleat. Some of these knots work ok, some hold even better than the cleat hitch, but I don't like knots that are hard to untie. Once I had to untie one of these knots with my knife!
The cleat hitch is easy to tie, even with one hand, and easy to untie, even with one hand. It holds well, and has enouh friction on the cleat to keep the human in control, not the boat.
Nylon dock lines come in triple strand and braided nylon. A braided dock line costs more, wears better, and usually has a loop spliced in one end. I prefer triple strand, because I believe it has more stretch and is easier to make a splice in. Nylon triple strand is one line that I will buy at Southerlands or Home Depot by the foot, Southerland had good prices last time. Avoid polypropylene which looks similar, it lacks UV resistance and has little stretch.
CAUTION: Many building stores have a cheap line that looks similar to a sailboat line with multicolored braided strands. I avoid these like the plague, they have no UV resistance, are not strong, and tangle easily. The core is usually made from what looks like a piece of paper folded into roundness and then has threads braided around that. An accident waiting to happen, this crap has no place on a sailboat. Because of the lack of UV resistance, they will actually cost MORE than a good line which can last for 15 years or more. A very good example of "you get what you pay for".