I guess the decision to tip comes down to whether you consider crew, professionals employed by the boat or service personnel hired to make your visit pleasant.
It's pretty clear from this thread that the vast majority of people understand the "reality" of how crew members are compensated. Whether you "consider" the compensation arrangement between the boat and the crew to be fair/adequate or not doesn't enter into it. Nor should it. Once you understand the reality of it the decision on whether you think the person deserves a tip or not, and if so how much, should be based entirely on the value you place on the service provided.
To be clear: YOU DO NOT HAVE TO TIP. I'VE NEVER SAID YOU DO. I'm merely making sure people understand their own motivations for tipping or not, and what the ultimate impact of their logic would be if it were universally applied to the reality of the situation.
So, let's look at a typical example from a purely mathematical standpoint:
- People understand the reality of the situation is that crew is not paid by the boat, they work for tips. Whether you think that is "right" or not doesn't matter - in this discussion or in reality. When you know this is the case, you must accept the baseline reality. That's just the way it is. (Hold on, I haven't said the reality is "you have to tip." Stay with me here. All I've said is "this is how the crew is compensated.")
- Since you know that... you understand that the cost to you as a passenger of this 2-tank dive charter is $85 + whatever you think the crew deserves as a tip, including ZERO. (Don't tell me "I think $85 is enough for the trip" as I've just said that is an option - you determine the cost. If at the end of the trip you want the cost to be $85 + 0, that's fine. But stay with me...)
- As a passenger on the trip, you will receive the benefit of some level of service provided by the crew. There is no diver who receives ZERO service from the crew. You may not need your "hand held" or your gear set up, but you do need the boat cleaned, fueled, geared up and ready to go when you get there. There's a certain baseline level of service that even the most autonomous diver receives from the crew. Even if it's making sure some diver who does need his hand held doesn't impact your ability to enjoy the trip. At a minimum, you benefit from the crew's presence when the captain yells "cast off" because without the crew the boat would never leave the dock at that point. (Hang on, I still haven't said you have to tip, or how much. Just making sure there's an understanding that you have personally received some benefit from the crew's service.)
- Since #1 and #3 above are true... you know that that the crew has not yet been compensated to render services from which you have benefited. Further...
- Since #1 and #2 above are true... you know that that you have not yet paid for any of the services that the crew has provided and from which you have received some level of benefit.
- Accordingly, at the end of the trip...you understand that you are able to decide whether the crew should be compensated for providing a service from which you have received some level of benefit. (Remember, given the reality of the situation, the "fairness" of the compensation arrangement between boat and crew doesn't matter.)
So, as mentioned above, the passenger at their sole discretion needs to weigh the value of the service from which they've received some benefit and determine what compensation the crew receives. You are free to TIP or to NOT TIP for whatever reason you may choose. (Minimizing or even eliminating the tip in response to poor service is always fair game, but is a different issue.)
Weigh the service rendered and compensate accordingly.
However, giving what you know to be true, if you decide to tip ZERO you just need to understand that you are telling the crew "I expect you to provide me a service without being paid."
At that point you need to look into your own heart, understand what your motivations are, and determine whether that makes you or the crew member the one with "a hand out" and an expectation of getting "something for nothing."
Beyond that, there's the simple and obvious economic impact of what would happen if your desire to not tip and have the boat and the crew determine how much the crew is paid: You will pay more than you are paying now for the trip.
Right now you can pay "$85 + whatever you want" including ZERO for the trip. You have the freedom to decide what the final amount is.
If tipping were eliminated the boat would pay the crew. (The crew is willing to
risk working for free and work hard to earn something, but a guarantee of no pay is a different story.) Assuming for discussion that fair market value of compensation for the crew is equal to what they would receive from an average tip of $10 per passenger on a full boat, that's what the crew would be paid by the boat. But the boat's not always full. And there are other costs associated with simply processing the payment to the crew - time to process payroll, bank fees, accounting costs, etc. As a business/employee relationship there are new liabilities, tax implications, etc. To cover all these costs, the boat will need to collect more that $10 from each passenger in order to pay the crew fair market value. A lot more. Probably twice as much.
So, your emotions have caused you to decide that in order to avoid the financial implications of the custom of slipping a guy $10 as you get off the boat you'd rather put in place a solution that is likely to cost you $20.
Given the facts, even the most callous, bitter, resentful people should be gladly giving out "average" tips since the fact is it's actually cheaper for them than the alternative.