Dinghy sailing is the activity of sailing small boats by using (1) the sails an (2) underwater foils (daggerboard or centreboard and rudder). It also involves adjusting (3) the sail trim and (4) balance by movement of the crew, particularly in windy weather ("move fast or swim"). In rivers and tidal waters the effective choice of route in terms of existing and anticipated wind shifts (5) and currents (6) can be important.