Gratuities are not included in your bill. Please remember that your captain is working in a service-industry job. In California, that means you are expected to leave a 10–20% tip on your total bill, just like you would for a restaurant server), based on the quality of service you feel you received.
Cash is, of course, preferred, but you are welcome to have the tip added to your card on file the day of your trip.
Thank you for your kind consideration!