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. Rolling hitch One of the most underrated knots. Ideal for transferring the weight on an anchor chain or rope from one secure point to another.
Double sheet bend The belt and braces version of the sheet bend.
Recommended for joining ropes of unequal size. Round turn and two half-hitches Ideal for securing fenders for long term, and also for securing to mooring rings and so on. It can be tied under tension. A fast way to attach a rope to a fixed object, which may need to be moved or adjusted quickly. Ideal for attaching fenders, but has a tendency to slip if left for long periods.