We'll define transitional rod holders as those that can clamp on to something sturdy, like a bow rail or tower leg. Examples are made by Lee's Tackle, C.E. Smith, Taco Metals, Attwood and others. It's critical that you accurately measure the diameter of where you intend to mount them to get the right-size rod holder to ensure a good fit. When using these various types of clamp-on units, whether drifting, trolling or underway, it's always a good idea to employ a safety line on your rod/reel combo to prevent a wicked strike, rogue wave or rough seas from causing it to get unceremoniously launched into Davey Jones' locker. I have used clamp-on rod holders with great success over the years, and there's typically a size and shape that will meet both your budget and performance expectations.