In the 16 years I’ve been cruising, I’ve seen many people fall ill and be taken off the ship in port or even evacuated at sea by helicopter. While I have always hoped for their speedy recovery, I have also wondered if they had purchased travel insurance.

It’s certainly tempting not to. How many times have you returned from a trip safe and sound and kicked yourself for spending a couple of hundred bucks to insure against some calamity that never transpired? (Plenty, God willing.) But it only takes once, and it doesn’t have to be much of a calamity to deep-six your sizable cruise investment. A jury summons can do it, or an attack of appendicitis, or a missed connection on the way to the ship.

In my opinion, all cruise vacationers should buy travel insurance. But where to start?

The basics

Most cruise lines offer a travel insurance package that can be purchased when you book your cruise. There are also many third-party (independent) insurance companies like Access America, Travel Guard and Travelex (to name a few) that offer coverage which can be purchased either directly from the company or through a travel agent.

* Coverage. Most travel insurance policies include coverage for five kinds of problems: trip cancellation (or interruption), trip delay, emergency medical expenses, emergency medical evacuation, and lost or stolen baggage. Many policies also offer round-the-clock travel assistance to help you replace a lost passport, rebook a reservation, or cope with other travel mishaps. The big draw is the trip cancellation coverage. In fact, according to Dan McGinnity, a spokesman for Travel Guard, 80 percent of Travel Guard’s claims are for events that happen before the ship leaves the dock: illness, injury, jury duty, a sick family member — you name it.

* Cost. The cost of travel insurance is usually based on the traveler’s age and the trip cost. Typically, the insurance cost will run about 6 to 8 percent of the trip cost, but it can be less. For example, a 59-year-old traveler on a $3,000 cruise can purchase a Travel Guard “Protect Assist” policy for $145. A similar policy for the same 59-year-old traveler would cost $129 from Travelex and $131 from Access America.

* Comparison. Costs and coverage do vary, and it’s in your best interest to do some comparison shopping before handing over the insurance premium. A nifty little website, insuremytrip.com, allows consumers to compare plans among 16 travel insurance providers.

Cruise line vs. third-party insurance

There are several key differences between insurance policies offered by cruise lines and those offered by independent insurance companies. Cruise offerings generally cost less than third-party insurance, and they sometimes give more protection. But what you won’t get, as a rule, is protection if the cruise line goes into financial default and ceases operations; third-party insurers generally do cover such events.

While all cruise lines offer the five basic components of coverage, most cover only those parts of the trip that you purchase directly from them. For example, if you book your airfare separately from your cruise fare, or if you drive to the port of embarkation, you won’t be covered for that travel segment under most cruise line policies. With third-party insurance, you can purchase a protection plan that covers the entire trip.

“With Travel Guard’s cruise coverage you are covered door to door, ship to shore,” says McGinnity, and the same is true of many other independent policies. Moreover, third-party insurers usually offer special coverages that cruise lines generally don’t offer, e.g. coverage for out-of-pocket medical expenses and coverage for pre-existing medical conditions.

If you have a pre-existing medical condition, you must read your insurance policy carefully. To qualify under most insurer’s terms, you must be in good health and medically able to travel when you purchase the trip; moreover, you must also have been healthy for a full 60-180 days prior to booking. In addition, the policy must be purchased within 15 days of paying the trip deposit. Few cruise lines automatically offer a waiver for pre-existing medical conditions, and when they do, it’s usually at an additional cost with many restrictions.

Another peculiarity of cruise line policies is the “cruise credit.” If a passenger needs to cancel or interrupt a cruise because of a pre-existing medical condition, another illness or injury, or any other covered reason, many cruise lines will offer the unlucky traveler not cash but a credit towards a future cruise. For cash back, it’s better to go with an independent.

One last factor to consider is how medical claims are handled. For the most part, third-party insurance provides primary coverage, i.e., the insurance company pays the traveler directly for any medical claim. Most cruise lines, on the other hand, provide secondary coverage, which means that you must file your claims through your regular medical insurance carrier; you will be reimbursed by the cruise line’s insurance company only after those claims are settled.

Emergency illness aboard ship

What many Americans don’t realize is that their regular health insurance doesn’t necessarily travel with them. Medicare recipients, for example, are often surprised to find that they do not have coverage outside the country. If your regular policy won’t cover you abroad, evaluate your needs and shop around for the plan that suits you best. Even if your health insurance does cover overseas expenses, you may still want to purchase a medical assistance policy to fill in any gaps.

One big gap in most medical insurance policies is medical evacuation. The vast majority of traditional health providers do not provide coverage for air medical evacuation and transportation services. According to Medjet Assist, an Alabama-based evacuation operation, domestic air medical evacuation services average $10,000 to $20,000, while international transports can exceed $75,000. If you travel more than once a year, consider buying an annual policy. These are available for as little as $205 a year, and you’ll know you’re covered when you want to take that last-minute trip.

Caveat emptor

Cruising is exciting, but it can turn into more of an adventure than you planned if you discover that you aren’t covered for the unexpected. The benefits of travel insurance can be great, but it pays to know which insurance is best for you. Go over the fine print carefully, and be sure you know what you’re getting — and what you’re not getting — before signing on the dotted line.

“Many times passengers return home wondering why they purchased insurance; after all, nothing happened and they could have saved that $150,” says Bonnie Buchanan, a travel agent with CruiseOne in San Antonio, Texas. “But, it’s the one time something does happen that will make up for every time it was purchased and not used.”

So, go ahead, part with the cash. Someday you’ll thank me.