Obviously, tips are not required, but they certainly are appreciated by the crew.
A standard and fair tip tends to be $5 per tank per diver, which as Canucklehead said, is $10 per person for a two-tank dive, $15 for a three-tank dive. If you think they deserve more, then by all means feel free to give them what you think is fair. However, I agree, that if they didn't do anything and didn't lift a finger for you, then tip less as you see fit.
Someone suggested $5 per day, that is actually pretty low and is even less than 10% as some have suggested. Keep in mind that these guys work very hard before, during and after you get on/off the boat. The tips are typically split among the entire crew, whether the crew consists of 2 or 5 crew members depending on what boat you are on. So this means at best, they are getting $2.50 each if you follow the $5 rule. For a two-tank dive, these guys put in an average of 5 to 6 hours, or even more sometimes. Hopefully this will give you some perspective.
As far as whether to tip everyday or at the end of the trip. Again, that depends on who you are diving with. If you are going to have the same crew all week, it is fine to wait until the end of the week. However, if you are on different boats and/or have different crews each day (very likely with the larger operations) then I recommend tipping everyday. While most of the divemasters/captains are honest and won't cheat their co-workers, don't depend on them to be honest and split the tips up fairly at the end of the week among 5 or 6 or more people. Make sense?
A little off topic, but someone referred to it "like tipping in a restaurant" where 10% is the starting point. Actually, I don't know if you have ever worked in the restaurant industry, but I put myself through college that way (over 10 years ago) and the standard THEN was 12% to 15%. Standard tipping for restaurants these days is more in the 15% to 20% range and 10% tip typically indicates very subpar service within the industry and restaurant regulars. Inflation affects the service industry too, don't forget that.
As far as tipping the owner of the dive op, I will use myself as an example. If I take a trip out or am working with a student on the boat, and receive a tip, I give all of the tips to my crew, that is my personal choice. I have an excellent crew and in my opinion, they deserve more than I do...AND...it can help make up for those who don't tip at all
However, this policy really depends on the operation. For example, there are several independent operators that run the whole show. They are the owner/operator and divemaster. They dive everyday and do not have a full time divemaster. In my opinion, these types of owners deserve to receive tips just as you would tip any other divemaster, they are still providing you service, and probably as good or better as a normal crew would. In most instances, the tips are that owner/divemasters "paycheck". The money you pay for your dives goes right back into the business and to pay expenses (many more expenses that most of you are probably aware of). None of us are getting rich and it is very expensive to run a dive operation here.
Now, on the other hand, if the owner of a larger or high volume shop like Dive Paradise, Aqua Safari, Sand Dollar, Dive with Martin, Papa Hogs, or Aldora, etc. etc. were to get on the boat as the divemaster, this is more than likely a specal occasion or a special treat for the customers and a tip would not be necessary in my opinion, they probably would not accept the tips or just tell you to give it to the crew. The truth is, the owners of the larger dive ops don't have the pleasure of diving everyday because there is just too much to take care of on land. I run a small operation obviously, but my focus these days is on students and running the office. I am fortunate to have an excellent crew that I can depend on to take care of things on the boat
I hope this provided perspective without offending anyone because that certainly wasn't my intention!
and there's a good chance they'll get more.
