Small Fry was asking about crab davits so I thought I would share mine. My boat has an aluminum rail with enough room in the corner to accept the davit. I decided to install here so the mount won't be in the way when no in use. I started with a heavy duty stainless steel vertical pole holder. I carefully bored 2 holes, one through the rail corner and one through the transom. I mounted the holder with stainless bolts and used the included rubber gasket. I had a friend machine a nylon sleeve that would accept my aluminum davit.
I bought my davit from Englund Marine in Astoria for $99. It is schedule 40 aluminum 80" long and comes with a side and bottom bracket. I didn't need the side bracket for my install but I bolted the bottom bracket using oak wood block cut at a slight angle to make level.
I have replace the pin shown in the picture with a bolt that I leave in and I notched out the bottom of the davit to stradle the bolt. This way there is no hardware to mess with when placing / removing the davit.
I also added a 1" stainless brace which provides a spot for a cleat to tie off the rope for the pots.
I used this setup a few times this season and it works great.