It makes sense to me that Truth Aquatics would provide the watchman since they have a larger staff and more intimate familiarity with the boat than Kristy. JMO
The crew was way more familiar with the boat, but there was only six peoples in the crew. A fully manned watch by coast guard standards would need three people on watch throughout the night. This means the crew would run up a safety concerning sleep deficit over say, a three day trip. Thus, they may ask the chartering company to help out.
The arrangements could also be more casual: Maybe say: We will have somebody in the wheel house. Can one of your people that stays up later take a watch on a deck? Maybe a dive assistant that likes to get up early for equipment checks? Ok, they can relieve the other person. Our cook can be relatively on an early watch while she preps for breakfast. Sure, we”ll talk later….I expect that providing a night watchman was spelled out in the contract between the two companies.