if the DM is also an owner or the partner (married or not) of the owner I generally still tip but less. Owners that I've been out with have turned down tips. Those are the ops I return to.
Let me describe my day as a DM. I'm an unpaid volunteer who works only for tips. I need to arrive to the boat 2 hours before you do. I help the captain get the boat ready. I may have to stop at the shop to bring tanks, rental gear, snacks, etc. I load all the stuff you need and check our safety equipment while the captain does the engine and electronics checks. When you show up I greet you with a smile, and carry all your gear from your car to the boat. We don't like our customers to carry anything except for light, personal stuff. I have to do that 18 times or so if we have a full boat.
Once we have you loaded we get you settled in and get underway. After the captain introduces the crew, I release the lines and help get us moving. Then I give the boat briefings on USCG regs and safety followed by amenities and how to get on and off the boat. I then bring you drink, snacks, help with gear, setup and answer any questions. Once our dive site is known, I give a dive site briefing. Some of you need extra help so we get that settled out.
We get to our site and I drop in first with the dive flag. Sometimes I have to bounce dive a site to check conditions.
I stay to the max of my NDL and surface with the last few divers. The other DM helps you all back on the boat taking cameras, spearguns, fins, markers from you as you climb up. the captain does a roll call and we take our surface interval. Again, we cater to your needs and get ready for dive #2. The other DM and I swap and I play deckhand. I help you all get in the water and repeat the steps of getting you out at the end.
After our dives, we head home keeping you all happy. We secure the boat and then unload all your gear and bring it back to your cars. As you leave, you slip us a few dollars as a "thank you" for our exceptional service. When you leave we clean up, secure everything, load rental gear into whatever vehicle goes back to the shop. We count the tip money and split it evenly. We have to take care of our own gear and then fill tanks back at the shop and get rental gear ready for tomorrow.
is all this worth $10 or $20 to you? I'd like to think so. If something happens, we have very advanced training that hopefully you will never see in use. How much is that worth to you? We had to pay for it. Our gear takes a huge beating and we need to stick with quality gear. Yes, we tend to get a nice discount but we still pay for gear that most divers don't need. We keep spare parts in our own bags because we know a customer will need an o-ring, mouthpiece, snorkel, mask, a hose or a reg sooner or later. We paid for that too.
This all makes for a long hard day. But it is HUGE fun and we get to share our passion and experience with all of you!