Carnival (CCL 0.68%) recently announced its Shore Excursion Best Price Guarantee. If you book a Carnival shore excursion and find a comparable tour for less offered by another operator, then you will receive a 110% credit of the difference.

If you're someone who goes on cruises, then you likely already know that once you're sitting on the pool deck -- drink in-hand -- and enjoying the sunshine, it's highly unlikely that you're going to be concerned about paying an extra few dollars for a shore excursion. And receiving this 110% credit requires more work than you might anticipate (more on this soon). Therefore, Carnival's most recent initiative isn't likely to lead to market-share gains vs. Royal Caribbean (RCL -0.05%) and Norwegian Cruise Line (NCLH -1.10%). However, when it comes to market share in 2013, the results might surprise you.

2013 market-share results
Carnival is still the market-share leader for the cruise line industry. On the other hand, due to several on-sea missteps, it's possible that you would have expected Carnival to suffer significantly in this regard.

At the end of 2013, Carnival's namesake brand owned a 21.2% market share for the cruise line industry. Its Costa Cruises brand owned 7.7% market share. And its other popular brands: Princess, AIDA, and Holland America, owned market shares of 6.1%, 4.6%, and 3.3%, respectively.

Royal Caribbean's namesake brand is second only to Carnival's namesake brand, currently owning 16.4% market share. Its Celebrity brand owns 4.4% market share.

Norwegian Cruise Line owns 7.6% market share. And Walt Disney owns 2.5% market share.

This is a positive for Carnival, but not if its top-line engine has stalled:

CCL Revenue (TTM) Chart

CCL Revenue (TTM) data by YCharts

Carnival must be innovative in its attempt to maintain, or expand, its market-share position. With that in mind, let's take a look a closer look at its most recent initiative.

Working on vacation
If a cruise line wants to offer a 110% onboard credit of the difference for a comparable share excursion, what do you think would be the easiest way for this credit to be rewarded? You're probably going to say finding a link to the comparable shore excursion and then presenting it to Carnival. That would make sense and allow you to spend the majority of your time on vacation.

Instead, here are the following requirements to receive this credit. First, the cruise you're on must be sailing out of North America. That's understandable, as well as likely. Second, if you find a comparable shore excursion for less, then you must fill out a claim form. On this form, you must fill out the name of the comparable tour, where the tour was advertised, the duration of the tour, the price of the tour, and any added items that the tour offers, such as lunch, drinks, transportation, and admission fees. Third, the comparable tour must be on the same date as your tour. Fourth, you can fill out the claim form prior to or during your cruise, but not after. The terms "claim form" and "vacation" don't go hand-in-hand. 

The good news for Carnival is that since it's offering a 110% onboard credit, this initiative doesn't cost it much. This can be seen as low-risk/low-reward initiative.

The bottom line
Carnival's Shore Excursion Best Price Guarantee isn't going to help get its top-line growth out of the mud. If anything, it's a sign that Carnival may be failing to innovate and fuel top-line growth. Investors may want to set their sights on Royal Caribbean instead, at least for now. For more information on this topic, you can read, "A Bullish Sign for Royal Caribbean." As always, please do your own research prior to making any investment decisions.