Before you go buy a rod holder go look at the powder coated models by Down-East.
I've had them on two different boats and they are BULLET PROOF!!. As a bonus, they quick release by pulling the rod straight towards you... instead of up and out. This quick release allows you to set the grab the rod and set the hook in one clean motion. How many times have you grabbed for your rod and lost the fish while you tried to get it out of the rod holder?
Down-East rod holders were my first purchase when I got my new boat. I have one set mounted to the side rails, and another pair that I can bolt to the transom when I am fishing more than two people. Neither required me to drill any holes in my boat.
Does anyone else use these great rod holders??