Ranger Boats Handrail Mounting

Baseplates are available in Marine board or Aluminum
There are also two mounting options, Thumbscrews or Magnetics
For speed of removal, magnetic mounting is fastest. Thumbscrew systems use 2 thumbscrews only to hold a baseplate to the pedestal.
Both use these attachement mentods to prevent damage should the downrod hit an underwater obstical.

To fit to your boat, measure from the center of the rail out to the rub rail on the boat.
Add 2 inches to that measurement
That is the span or "B" dimension on the baseplate drawing above.
Select the baseplate that will allow a proper span.