Abstract: A relatively small and light weight personal watercraft includes a driveshaft tunnel which permits the driveshaft housing of a string trimmer apparatus to be installed therein. The string trimmer apparatus is modified by removing the string trimmer or other head which may be attached, installing a propeller(s) or impeller(s), removing any handles from the string trimmer, temporarily removing the power head so that driveshaft housing may be installed within the driveshaft tunnel of the watercraft, installing a fairing (if desired) and/or handlebars, and reattaching the throttle control to the handlebars. The modified string timmer may be used as both a power system for the watercraft and also provides directional control by turning the attached handlebars or fairing in order to rotate the power system about an axis concentric with the driveshaft and thereby change the direction of the thrust line of the propeller(s) or impeller(s).