Close up the cut, tear, or hole in the aluminum hull as tightly as possible. In most cases a jet boat is too heavy to lift above the water level for a dry fix so most of the time you will have some water present. Using a Toilet Bowl Wax Ring work the wax into the cut and all over the surrounding surface. The claim is the wax is sticky enough to apply and adhere under water and that it cleans up easily when getting ready to do a permanent repair back home. The only drawback would be high speeds may cause the soft patch to leak from water pressure under the hull when on step so constant monitoring of the "fix" should be done and low speed utilized as frequently as possible.