In a world where owning stock in a company rarely gets you anything beyond the investment value and a steady source of paper to feed to your shredder, it is refreshing that the cruise industry continues to maintain investor benefits in the form of onboard credit (OBC). We've got the rundown of the benefits offered per cruise line, how to get the stocks, plus how and when to snag the credit.

What Are the Benefits of Owning Cruise Line Stocks?

There are four publicly traded cruise line stocks that earn benefits for shareholders: Carnival Corporation, Carnival plc, Royal Caribbean Cruises Limited and Norwegian Cruise Line Holdings Limited. It gets a little complicated because two of the four stocks are Carnival companies -- Carnival Corporation (under the symbol CCL on the New York Stock Exchange) and Carnival plc (under the symbol CCL on the London Stock Exchange and CUK on the NYSE). Since shareholders receive the same benefits regardless of which Carnival stock you own, we're lumping them together going forward. Disney stock is publicly traded, but the company discontinued all investor benefits in 2000.

Benefits for the three companies are based on the length of cruise, starting with short cruises, earning $50 in onboard credit. Mid-length cruises (seven to 13 nights on Carnival, seven to 14 on Norwegian and six to nine on Royal Caribbean) earn $100 in credit. The benefits top out at $250 for cruises of 14 nights or more on Carnival and Royal Caribbean or 15 nights on Norwegian.

Royal Caribbean adds an intermediate benefit for cruises of 10 to 13 nights, which earn a $200 onboard credit.

All Carnival brands -- which include Carnival, Princess, Holland America, Seabourn, Cunard, Costa, Aida and P&O -- earn benefits, though the amounts are adjusted slightly for European and Australian brands.

Royal Caribbean stockholders only receive the benefit on the company's wholly-owned brands -- Royal Caribbean, Celebrity and Azamara Club Cruises, with the exception of Celebrity Xpedition cruises. No benefit is given for sailing on Pullmantur, TUI or Croisieres de France, lines for which Royal Caribbean, Ltd. holds partial ownership.

Cruises on all brands operated by Norwegian Cruise Line Holdings, Ltd., including Norwegian, Oceania and Regent Seven Seas are eligible for the benefit.

Before you get too excited, all three companies have rather extensive restrictions in the fine print, including the fact that the benefit programs are subject to change at any time. Here are the current details, including how to submit your claim for the benefit from each company's lines: Carnival, Royal Caribbean and Norwegian.

How Do You Buy Cruise Line Stocks?

Buying the stocks requires a brokerage account, but online brokerage sites like E-Trade, Fidelity and TD Ameritrade are options if you don't already have a stockbroker. Some banks, like Capital One and Wells Fargo, also offer investment services from their own online portals. Most banks and online brokerages charge a small fee for each stock trade or purchase.

How Much Do I Need to Invest?

While you can purchase as many or as few shares as you'd like, all the cruise lines that offer investor benefits require a minimum of 100 shares to be eligible for the credit. At current stock prices, you are looking at a substantial initial investment -- somewhere between $5,000 and $13,000, depending on which parent company you invest in and the cruise line's stock price at the time of purchase.

Is It a Good Idea to Buy Stock in a Cruise Line?

While Cruise Critic cannot offer investment advice, Cruise Critic members on the message boards have reported that holding cruise line stocks over time has been beneficial, particularly for those who take multiple cruises per year.

Their reasoning is that if you invest $5,000 and typically take five cruises per year, each one with $100 in onboard credit (i.e., free spending money), your investment "earns" $500 or 10 percent per year. There are some fine print details that could alter that, though. In most cases, the investor OBC is superseded by other special offer credits, so no stacking. If you shop the deals and frequently get OBCs on your own, then the cruise line's stock perk is less of a benefit after all.

It is good to note, however, that even with other OBCs on your account, you may be eligible for the portion of the stockholder benefit credit that exceeds the other credit. So, if your booking came with an onboard credit of $75 and your cruise line stock benefit is $100, you may still be able to get the difference of $25 applied to your cabin.

Also know that the benefit is limited to one credit per cabin per 100 shares on each sailing and is nontransferable. You will be required to submit a copy of your brokerage statement, usually two weeks before sailing. The name on the statement must match the name of the person sailing, so no sharing among friends, unless you plan to jointly own the stock. There are exceptions in the fine print for cases of jointly owned stocks, but the restriction of having 100 shares per cabin still applies.

Other message board members who have owned cruise line stock for years report that even though the stocks have had some turbulent times in the past, over the long haul they have risen in value, earning a return on the investment above and beyond the investor benefits earned in the form of onboard credits. As with all stock purchases, you do take a risk that the cruise line stocks will not perform as well in the future as perhaps they did in the past, so make sure you understand all the fine print before you invest.

As with any financial decision, only you can decide what is best for your personal situation; Cruise Critic can neither support nor advise against your decision to purchase stocks. We strongly advise doing your own research and seeking out the counsel of a financial adviser before making any stock purchase.