I actually pay my DM/deckhand a decent trip rate, $75. Other charters that I am familiar with pay only $25 or not at all and the rest comes from tips. I think they are the best people I could hope to get and I pay them as such. Obviously the inspected vessels that take out more than 6 can be pretty lucrative if everyone tips 20% even if the deckhand only makes $25 from the charter as wage.
Not paying the DM/deckhand a wage is another way of cutting costs so that the boat can still run with a small number of people onboard. To break it down to the basic economics a trip to the Bart costs me $100 in fuel (marina gas is $5.00) and $75 to the deckhand. So I need 3 paying divers to beat operating costs before we talk about insurance ($4000), dockage ($5400) and maintenance ($you don't want to know$). Don't forget sales tax takes 6% of my side too. So it would be far cheaper to trailer my boat, run uninsured and not have a deckhand, there are some guys that do it here!!! Hell now I want to be a deckhand, he is making more money than me!!!
In seriousness, hopefully you can see the temptation to not pay a DM by running those numbers. Worth noting is that those inspected vessels have about the same yearly cost and operating expenses but they have to pay a Captain as well since none of the owners are running them.
I feel like I should say that to me
good tips are a bonus but
tips in general are customary.
Personally I tend to overtip (>20%) both eating in a restaurant or on a charter unless I feel I have been neglected or worse. This is probably because I waited tables for 8 years while I was in high school and college (yes it took alittle longer than it should have to get out of college!) and the service industry is rough unless you are in a 5 star or high end establishment. If you treat others with respect and are rational you are not representative of the public at large. Fortunately divers tend to be of a higher caliber person as a whole. but I have really digressed at this point.