Dave,

My entire rod holder is made from PVC. It's strong though. The size you use will depend on the size of your rod handles. I used 1". I have one handle that's a little tight, but it fits. Make sure to leave enough room between each one for your reels. Before you glue or bolt anything down, make sure everthing fits and you can reach it. Also, mount your oars and anything else that might go on the same side and make sure you have plenty of room.