Here in the PNW, salmon are king and a downrigger is pretty much a necessity to get your tackle down to where the fish are. I had a Scotty manual downrigger but needed a way to mount it to the boat. Here’s my solution in pics. Note that I used a locking winch handle so I don’t need to worry about it coming out when I don’t want it to.
Or just use a deep six, dispy diver etc, have had lots of success with them but a down rigger does give more adjustment and overall depth. I find what’s attached to the end of the line more important though.