Now the caveat - there are dangerous situations out there in the world of kayaking (as there are crossing the street) but like crossing the street, we can control these situations with a high degree of confidence, given the right tools and the right knowledge.
Since the most perilous types of kayaking are by sea and whitewater, I'll restrict my answer to concentrate on these pastimes.
When you tan indoors, unlike outdoors under the sun, you won't need the same sort of lotions. Outdoor tanning, due to the relatively unregulated light of the sun, requires a lotion with a significant SPF. The SPF (which stands for Sun Protection Factor) allows you to stay out longer in the sun without risking a burn. For instance, if you use an SPF 16, you can stay in the sun without risking a burn sixteen times as long as you'd be able to stay out without the lotion.
If you're intent on maintaining that tan, the costs involved in your twice to three times per week visit to your tanning salon may be higher than tanning bed prices. For instance, if you pay $20 a week to manage that tan, that's over a thousand dollars a year.
Besides this, many people don't have time to visit a commercial tanning bed often enough to properly maintain their tans.