[TomC]

They likely would not do it that way. Presumably, they would simply have you enter your bow numbers into a kiosk or phone app and have you pay for your requested time... when the Meter (Mer)maid comes by, all that has to be done is enter the bow number into a handheld device to confirm the fee has been paid. Won't matter if the boat is moved, or over-paid and left early. The next boat pays anyway - no using leftover time.