Here is the ONB schedule:
https://oilnutbay.com/wp-content/uploads/2021/02/FERRY-SCHEDULE-2.pdf

And Bitter End:
"Departures from Gun Creek to Bitter End: nearly every hour on the half-hour from 6:30am – 10:30pm There is no ferry service at 10:30am, 1:30pm and 8:30pm. To take a ferry at 11:30pm, please confirm the boat’s departure with the captain by 10:30pm.

Departures from Bitter End to Gun Creek: nearly every hour on the hour from 7:00am – 11:00pm. There is no ferry service at 10am, 1:00pm and 8:00pm. To take a ferry at midnight, please confirm the boat’s departure with the captain by 11:00pm"