There are a number of ways of reducing the running cost of existing ships by making use of power sources which are freely available to them in their environment. This paper first of all considers briefly some possibilities other than wind power and then discusses the use of wind as an auxiliary source of propulsion in power driven ships.

Ocean Currents. Ship navigators of course already make considerable use of ocean currents when planning economical voyages. However a number of rafting voyages made for various reasons in the last few years point to the possibility of sending bulk cargoes at slow speeds across some parts of the seas carried principally by the currents. The principal problem is perhaps the pure financial one of taking the capital value of the cargo out of circulation for the time involved in such transportation.