I suspect part of the reason for that is that the boats most commonly used for long-range cruising, which is when one is most likely to encounter "adventures," are sailboats. Most powerboats don't have the range for this kind of cruising. So you're not likely to get good stories about surviving storms and running low on rations and complex navigation from the average "my weekend cruise" powerboater.
There are a handful of books I'm familiar with about long trips in powerboats, but they are mostly connected with the fishing industry in the Pacific Northwest, BC, and SE Alaska. Books like "Alaska Blues," "Low Man on a Gillnetter," "Fishing with John," and "The Curve of Time" are some titles that come to mind that I have read.