Ashcraft used half of the broken pole — approximately six feet in length, by various accounts — as a makeshift mast. She stepped it in some improvised socket or wedged it against a structural member of the vessel, and rigged the storm jib — a small, heavy-weather headsail designed to provide drive in conditions where a larger sail would be dangerous — to it.
The storm jib is specifically designed to withstand extreme conditions. It is built from heavier cloth than other sails, with reinforced seams and corners. Its area is small — a fraction of the vessel’s normal working canvas — but its construction is robust. In conditions appropriate to its use, a storm jib can drive a vessel at significant speed.
The conditions appropriate to its use — which is to say, strong winds and heavy seas — were not the conditions Ashcraft faced for most of the 41 days. After the hurricane passed, the Pacific settled into the trade wind regime of the northeast trades: steady winds from the northeast at a consistent force, predictable swells, relatively manageable conditions for a vessel making a predominantly downwind and reaching passage toward Hawaii.
A storm jib on a half-spinnaker-pole mast in trade wind conditions is not an efficient rig. It is a rig that works. The vessel will move in roughly the right direction at a speed that makes the passage possible. With the North Equatorial Current adding additional speed from the east, the combination was sufficient to bring the Hazana to Hawaii in 41 days. That is what a jury rig is supposed to do: not win races, but make port.