The present invention discloses the methods and apparatus to acquire, record, and analyze data to determine the draft of a water-borne vessel and/or the amount of cargo that has been loaded in a water-borne vessel. The apparatus includes a portable, handheld housing containing means for use in positioning the housing in a predetermined location and spatial orientation. Such means can include one or more narrow beam emitting devices, such as lasers or other similar devices, or a camera or other image processing level sensors. The housing also containing an ultrasonic transducer and receiver, or alternatively, a laser emitter and receiver, that directs sound pulses or light, respectively, toward the surface of the water body in which the vessel is placed. Within the housing is electrical circuitry to receive either the sound or light beam signals, and from these signals produce a signal representative of the time of travel of the sound pulse or light. This signal will be transmitted wirelessly to a PDA or similar device that utilizes an arraying analytical technique on the received signals to determine the distance of the vessel above the waterline. The data representing the distance of the vessel above the waterline will then be either further processed by the PDA, or transmitted wirelessly to a central computer, for use in conjunction with displacement characteristics and cargo unit weight to determine the amount of cargo that has been loaded in the vessel. A collapsible or telescopic handle or other similar device may be attached to the housing to both facilitate carrying the apparatus to the field site, as well as to facilitate the positioning of the housing at the desired draft line while permitting the marine surveyor to stand on the vessel deck. For ease of use controls for operating the apparatus are preferably attachable to the handle.