transponders t 1 t 2 t 3 t 4 may be disposed directly on the electrodes e 1 e 2 e 3 e 4 or in the vicinity of the electrodes e 1 e 2 e 3 e 4 i e the transponders may be u201c attached to u201d the electrodes the acoustic ranging systems illustrated in fig4 a and fig4 b are examples for determining the geometry i e relative distances and bearings between different electrodes and the towfish knowing the geometry of the electrodes indirectly gives the relative orientations and distances between the electrodes one skilled in the art would appreciate that other modifications or variations of the acoustic ranging systems shown in fig4 a and fig4 b are possible without departing from the scope of the invention for example one may equip the electrodes with transceivers such that one can also determine the relative distances and bearings among the electrodes in another example in fig4 c the acoustic ranging system is implemented in a conventional csem having two electrodes e 1 and e 2 the transceiver 401 is disposed in the vicinity of the towfish 103 while the transponders t 1 and t 2 are on the electrodes e 1.