We use this one, The Boater's Log Book and Journal pictured in the link. Hardcover bound, about 1/2 in thick, and sells for $15.
Welcome to Adobe GoLive 6
It has a fuel log, radio log, maintenance log, equipment listing and I think 88 pages for passages. It's an informal format, with entry lines for start/destination, engine hours/rpm, distance traveled, weather observations/forecast and a half page section for comments etc. There is also some basic first aid/safety info as well.
We routinely log all trips, keeping track of days out, overnights out, and each book lasts about a year. In fact we even log it down if we checked the boat and ran the engine for a time over the winter season.
The active one is aboard, the others kept at home for a historical record and occasional review