Dinghy

A dinghy is a small utility boat attached to a larger boat. Dinghies are rowboats, or have small outboard motors —some use a small sailing rig. Dinghies are needed for any off-ship excursions from larger boats, outside of docking at suitably-sized ports or marinas.
When not in the above reference, a "dinghy" usually refers to a similar boat originally developed from that use, but now used in its own right for dinghy sailing or rowing.