We all understand, you don't like tipping. But do you really want/need a listing of all the ways that working on a dive boat is different than pumping gas?
Here in NJ dive boats are essentially run as hobbies by guys who love diving and own a boat. They are not a business like a full-service gas station. They do not have bookkeepers or accountants or a payroll system. Point of fact, they do not have employees. If the boat needed to pay the crew, the boat would need a bookkeeper, a payroll service, they would have to withhold income and payroll taxes, disability, unemployment insurance, make quarterly filings, etc, etc. All that stuff would add incremental costs to the price of the charter that would FAR exceed the extra $5-$10 a tank that comprises the customary tip.
I'll never for the life of me understand why some people get so blinded by their own biases that they will strongly advocate for things that are so obviously contrary to their own financial best interests. So keep pushing for the boat to pay the crew directly, and then instead of paying $100 for the charter plus $10-$20 in tips you'll be able to take your share of the credit for cutting the tips to zero and driving the charter cost to $130-$140.