If all you have ever booked in the past is a cruise ship vacation, then you’re used to receiving thick, glossy booklets that list each ship, each itinerary, and the price for each type of cabin during a given set of dates. With the simple flip of a few pages, you can compare how much you will pay for a seven-day itinerary in a balcony cabin onboard one ship versus a seven-day itinerary in a balcony cabin onboard another. You will know exactly which ports of call each itinerary offers, and exactly how much you will spend on excursions above the price of the cruise ship cabin itself. If you look to the back of those glossy booklets, you can even see the price for airfare packages and airport transfers, along with predetermined gratuities.

These kinds of booklets make it easy to comparison shop for a cruise ship vacation, and you may be disappointed to learn that similar booklets do not exist for private yacht charters. You can find literature about suggested cruising itineraries as well as literature about yachts and their base rates, but nowhere will you find specific yachts with specific itineraries and total package prices listed side-by-side like cruise ship trips.

You also will not find printed brochures that itemize the variable costs of yacht charter. These additional costs can be substantial, typically adding 25 percent and sometimes as much as 30 or even 50 percent to the charter yacht’s advertised weekly rate. Among these variable expenses are food provisions, wine and beer, fuel fill-ups, marina fees, ship-to-shore transfers, taxes, national park fees, crew gratuities, and even cruising guides and toys like water skis in some cases.

These add-ons are not listed as standard fees because every charter is different. Two different groups can charter the same exact yacht in the same exact place and run up a completely different set of bills for the yacht’s owner.

For instance, one week’s guests onboard a powerboat may want to zip back and forth to a dozen different top-dollar island marinas a day, burning up fuel and spending lavishly on restaurant lunches before snacking on caviar and Dom Perignon champagne back on the boat each night.

That same powerboat, the next week, may host charter guests who want to use far less fuel and cruise to just three islands during an entire week, always anchoring in the harbor instead of paying marina fees, and dining on freshly caught seafood after days spent snorkeling with the yacht’s free equipment.

Yachts--bareboat and fully crewed alike--have to account for these differences by making more costs variable than cruise ships do. You have the opportunity to do whatever you want onboard any charter yacht you choose, but unless you book one of the rare yachts that offer an all-inclusive rate, you need to understand that your choices will be reflected in higher or lower variable costs.

A good charter broker will be able to help you estimate your variable costs in advance, based on what you tell her about how you want to use the boat during your vacation. She will know how much fuel a given yacht tends to use, how far apart the islands are in your chosen destination, what a particular yacht’s chef is capable of producing on certain budgets, what dockage rates the local marinas tend to charge, how pricey the region’s restaurants are (if you plan to dine ashore), and other details that should give you a reasonable idea about your overall expenses.

Good bareboat company operators, too, can talk you through many of these costs beforehand, though with you literally at the helm of your own ship, you will ultimately be the person responsible for determining how much money gets spent overall. You could end up paying half-again the cost of the yacht itself, as sometimes happens with some fully crewed charters, or you could keep the purse strings tight, even bringing your own snacks from home to stock a bareboat’s galley for the kids.

No matter what total amount you expect to spend in your charter budget, a key factor to remember is that when comparing cruise ships to private yachts, it is the per-person rate that matters in terms of what you’re getting for your money. A $20,000 yacht that carries four couples may look at first blush like a ridiculous expense next to four $2,000 cruise ship cabins, but in my experience, the better deal—and the better vacation--is often the yacht, especially after all of the additional expenses are factored into each cruise’s total price.

You can learn more about how to compare prices apples-to-apples by reading the What Charters Cost section of CharterWave (yes, it’s free content). For a more in-depth look at getting the most value for your charter dollar, you can read Dream Cruises: The Insider's Guide to Private Yacht Charter Vacations, from which this information is adapted.