Figure of eight Ideal as a stopper. It prevents the end escaping through a block or fairlead. As a temporary measure it stops a fraying rope unravelling further. The original way to join two ropes of the same size. But remember to keep to right over left and left over right, otherwise you will end up with a granny knot, which may slip.
Sheet bend An ideal way of joining two ropes.
It does not slip and is easily undone when the tension is released. Bowline Undoubtedly, the most important knot in use on a boat. Everyone should learn how to tie it. It does not slip and can be easily undone when the tension is released. However, it cannot be tied under tension.