Split ring hangers. I made my own using galvanized pipe. 1/2" floor/wall flange. 12" x 1/2" riser. 1/2" tee on that bull headed. 2) 12" x 1/2" pipe on both sides of tee. Mount the flanges to your boat, screw in the "T" you made with the 3 pieces of pipe and you're good to go. If you use the split ring hangers, get the ones that have 2 screws on both sides, not the ones with the hinge. They break when locking down on the pipe. I reinforced mine by adding wingnuts to the screws. Solid as a rock. You can also put a flange on both sides of your boat, add risers of desired length. Put an elbow on each riser and take a measurement between the 2 elbows and connect them with a union. Great for longlining out the back of the boat! I'm a pipefitter so it was easy for me to make that kind.
Fishing is like pizza.......Even when it's not that good, it's still pretty good!
Member of Lanier Crappie Anglers.com or net