Sails suggest the idea of making use of available power. Often the type of sail will be relevant. Old-fashioned sails would suggest out-of-date methods, whereas racing sails might suggest the use of modern technology.
The colour of the sails may also be important. When we dream of sailing, we are highlighting how we feel we are handling our lives. We can either work with the currents or against them.
If we are sailing in a yacht there is more of a sense of immediacy than if we were sailing in a liner.
The former is more to do with one-to-one relationships, while the latter suggests a group effort.