I've been asked alot about using one of the Scotty #269 Fish Finder mounts on their kayaks and float tubes. The concern is the mounting plate that you secure your fish finder head to. It only fits certain models, but overall it is about the best way we have found to have a removeable fish finder head assembly.
What we do is make an adaptor plate out of a $5 cutting board you get at K-Mart or Wally World. In the photo, you see the Scotty #241 mount secured to the deck of the kayak. Then you can see the post coming up out of the top of that. Then you see the adaptor plate we made, with the fish finder head mounted to it. What we do is make the adaptor plate, then secure the post part of the Scotty mount to it, then secure the actual fish finder mount to that, and were done. The waterproof wire seal to the left of the FF is one of the Ancor units.
Hope this helps explain things a bit.
Perryc.