Knots could prove to be some of your best sailing companions. 
They need practice so that you can tie them perfectly and quickly when you need them. Your rope handling skills will be needed for mooring, anchoring, securing cargo, managing sails, preparing for a storm, towing another vessel or other needs.
The Basic Cruising standard requires you to be able to make the knots, bends and hitches listed below within 30 seconds.
Click on the links or on eack knot for a video. You can also visit the ASA (American Sailing Association) web pages for their knots made easy series.
Figure Eight - provides a quick and convenient stopper knot to prevent a line sliding out of sight, e.g., up inside the mast.
Clove Hitch - can be used to tie to a post. It does have two giant faults: it slips and, paradoxically, can also bind. It should be deeply distrusted when used by itself.Choose something else unless you are merely hanging a fender.
Reef (square) Knot - the Square (Reef) knot is used to tie 2 equal size lines together. It has many uses but not where safety is critical, e.g., you can tie a sail cover over a sail.
Round Turn and Two Half Hitches - is very useful for attaching to a ring, bar, pole, or dock post. Useful for hanging a fender as it is easy to adjust the height of the fender after the round turn, and then complete the knot with the two half hitches.
Double Sheet Bend - (the video is a single, for a double go around twice) - is recommended for joining two ropes of unequal size. The thicker rope must be used for the simple bight. However, it works equally well if the ropes are of the same size.
Bowline - makes a reasonably secure non-slip loop in the end of a piece of rope. It has many uses, e.g., to fasten a mooring line to a ring or a post. Under load, it does not slip or bind. With no load it can be untied easily. Two bowlines can be linked together to join two ropes.
Belay a line to a cleat - The Cleat Hitch secures a rope to a dock or deck cleat
You can also visit the ASA (American Sailing Association) web pages for their knots made easy series.