A good rule of thumb is 15% in the galley. Of course, sticking a wad of singles, say 10 bucks or so in the jar first thing will go a ways to greasing the attitudes. Be polite to the galley slave... it's a crappy job on a boat. If the action is not reciprocal, speak up, tell them (usually a she) their attitude is gonna determine what the tips look like at the end of the day.
The no cooler rule is getting pretty common I hear. I've done trips where no one bought a single thing from the galley... The backlash is fairly high prices.
Also, I've done trips out to, say, Cortez Bank, where the group was totally drunk when the boat left at 1:00AM the first day out, people puking in the bunks and generally making a mess. Get out there at prime time, and nobody fishing, all hungover and sick.
No greasy stuff for breakfast or lunch. Stick to sandwiches for lunch. A good hamburger always sounds nice, but mix that with more than a few beers, a mild swell, diesel exhaust, etc... and the greenies will be chummin. Ginger Snap cookies are good for sea sickness, take some with you.
The deck hands will be doing your rigging, clearing lines, and assisting with getting floppers (fish) onboard. If one clears your lines, and gets your fish onboard, give him a couple of bucks.
At the end of the day, heading back in, is when you want to fillet any fish you have, and weigh in for a jackpot if you set one up. It's easy to tip too much here, but just ask the guy how much he wants to fillet your bag. If it sounds too high, make an offer.
The water is not that warm out in the channel yet, but if you do get lucky and get a good yellow tail, get the deck hand to fillet it right away. Take one side into the galley and have them do a double sear, just sear the outside, no more than a minuet a side. Break out the wasbi and soy, and make sure the crew gets some.
--ron
Another thing. BANANAS ARE BAD LUCK ON A BOAT. If you see any in the galley, ask that they at least put them under the counter so you can't see em.