Permanately Mounting Downriggers on Gunwale Without Drilling New Holes
Case no one else had thought of this and is in a similar situation...
I have a large fiberglass boat. I could not mount a typical downrigger board parallel to the transom due to interference and width (8 feet). At least it would have been a pain in the hind quarters. And I was very hesitant to drill holes into the gunwale.
After much thought, I removed the built in rod holders (2 per side) and mounted a board along the gunwale using the rod holders themselves. Used pressure treated 2x6. Redrilled the rod holder holes into the board. 60 degree angle I think; easy as I have the proper tools. I reinstalled the rod holders into the gunwale through the "adaptor board" and using the front two rod holder mounting holes bolted it to the gunwale using a backing plate. I could only use the front two of each due to interference. The back two holes of the rod hollers are screwed into the 2x6. Effectively increased the gunwale height with an adaptor plate.
Obviously before installing I mounted 4 (2 per side) quick release, rotating downrigger plates.
Works fantastic. Yes, I could have used rod holder adaptor gizmos for the downriggers, but A) thats just more crap to deal with, and B) I was able to mount other things on that board like a tool rack / holder.
Soooo, if anyone else is loathe to drill holes into their gunwale, suggest trying this route.