The sailing space frame of the present invention is supported by three hulls, a rudder hull a dagger board hull and an outrigger hull. The space frame also includes two mast assemblies, a fore spar, and a crew's quarters. The space frame can couple with a vessel propelled by a fossil fueled engine, and convert the combined space frame/vessel into an efficient sailing vessel that does not require fossil fuel for the trans-ocean portion of its voyage between ports. The outrigger provides sufficient stability to the sail propelled vessel so that it can carry a large enough sail area to supplant the use of the fossil fueled engine on the open ocean between ports. When entering or leaving a port the vessel uses its own engines for propulsion.