46 CFR §401.451

1. (a)Except as provided in paragraph (b) of this section:
   1. (1)Each United States Registered Pilot upon completing an assignment at a change point designated in § 401.450, and
   2. (2)Each United States Registered Pilot upon completing a series of assignments totaling more than 10 hours with no more than 2 hours rest between assignments, must not perform pilotage services for at least 10 hours.
2. (b)In the event of an emergency or other compelling circumstances a pilotage pool may assign a United States Registered Pilot for service before their 10-hour rest period required under paragraph (a) of this section is completed. Pilotage pools must advise the Director of each assignment made under this paragraph.