Abstract: A trim tab indicator system comprising a pair of trim members hinged to the stern of a boat, one of each side of the center line of the boat and a hydraulic cylinder individual to each trim member having a first head at one end and a second head at the other end. The cylinder includes a piston and a tubular shaft connected to the piston and extending through the first end of the cylinder. A bracket is connected to the first head and has a surface complementary to the transom of the boat and is mounted on the transom. A tubular coil is fixed on the first head and extends axially within the cylinder, and a floating rod of magnetically permeable material is provided in the tubular shaft with a lower end engaging the base of the tubular opening of the shaft with its upper end extending into the coil such that movement of the trim tab changes the inductive relationship between the rod and the coil to provide a signal representing the position of the tab.