Notwithstanding any other provision of this division, any shipping company which regularly employed its employees, or expressed its intent to the board to use its employees, for piloting vessels on the Bays of San Francisco, San Pablo, and Suisun on or before July 1, 1983, may employ and use its employees in that manner in lieu of pilots provided under this chapter. However, this use of employees as pilots on foreign flag vessels shall be limited to five vessel calls per year for those shipping companies that have only expressed their intent to use their employees in lieu of pilots. This limitation shall not apply to those shipping companies which regularly employed their employees for piloting vessels prior to July 1, 1983.