Of course, individual quirks should be factored in. For example, some people have a poor sense of time and should figure in the cost of a flight to the next port when the ship pulls out without them. I take extra cash just in case I need bail. If you forget to tell your teens they can't call their friends back home 25 times per day from the cabin telephone -- cost $15 per minute -- it's a good idea to take the deed of your home along and just sign it over to the cruise line.

All the cruise lines make their passengers use some variation of an onboard credit card for their purchases other than gratuities and casino play. They ask you for a deposit for use of the cards, which can be done either by cash or credit card.

The cruise lines all have different names for their cards. For example Carnival's are called "Sail & Sign." The name that I love is Royal Caribbean's "SuperCharge." I get one of those "SuperCharge" cards in my hands, and I feel like a millionaire. No, make that a Super Millionaire. I can buy anything I want on this here little boat and just SuperCharge it!!

However, you can run into situations like this at check out the last day ; visualize me standing at the purser's desk just before debarkation. "I remember there was the Swedish soccer team that I met at the disco. I recall buying them a couple of rounds of drinks. But I don't remember signing up all 28 of them for that helicopter ride in St. Thomas." Are you sure??" If you're at all like me, this is the danger.

On the other hand, these onboard charge cards are wonderfully convenient. On the ship you really can go about your day carrying no money. The cards are accepted for anything you want to buy that is sold on the ship, whether it's in the shops, or for buying ship's excursions for the ports of call. The lone exception, on some cruise lines, is bingo cards. For some strange reason there are some cruise lines that will only take cash for bingo cards.

Yet, these same lines will let you go to their casino cashier and get cash using your charge card. I wonder if they'd throw you in the brig if they knew you were using that cash to buy bingo cards. The important thing to remember is that at the end of the week you're the one that has to pay the check !!!

Here's a guideline for figuring out expenses.