Technically, the head is the toilet on a boat. A head's operation is rather complicated, but once mastered, it should present no particular difficulty to the crew. Proper operation of the head is essential.
Simply put, the head macerates and chlorinates a certain very restricted class of waste materials prior to discharge, transforming them into a chemical compound that annoys, but does not kill, marine life. Foreign matter must not be introduced into the head under any circumstances. Although it operates on the principal of the chain saw (as the noise which accompanies its use suggests) it is highly susceptible to clogging. Heads that become clogged can result not just in considerable inconvenience, but in great expense as well, requiring the intervention of trained personnel with decontamination gear and remote-handling equipment, and in extreme (but by no means uncommon-cases) may lead to the abandoning of the boat.
The head on the Bumboat has two levers for operation. The top lever simultaneously fills the bowl with fresh water while emptying waste. The lower rocker lever has two positions; one fills the bowl with fresh water and the other empties waste from the bowl.
If you feel nature's call:
1) Enter the lavatory in the forward area of the cabin (beyond the galley on port side).
2) Close the door. If the seas are rough you may want to consider sitting on the head, regardless of your waste scenario.
3) Fill the bowl with some fresh water, then do your business.
4) Put NOTHING in the bowl other than what excretes from your body. Your body waste and toilet paper are the only acceptable bowl ingredients. The toilet paper is located in the door to your left (when sitting on the head).
5) After nature's call is answered, systematically operate the levers to remove the waste and clean the bowl. Clean all residue in bowl (and outside if you have a bad aim) before exiting lavatory.
6) Make sure the lavatory door is latched.
The operation of the head in our sailing vessel is much more complicated. The sailing head consists of levers and hand pumps whose operation is beyond the scope of this site. If nature calls on the sailboat, your best bet may be a bucket.