This is my setup. The round connectors to the upright have teflon inserts and it swivels easily, with wingnuts to tighten when needed. Here it is mounted too low so I slid it up the upright and it works well now. I store the engine below for a passage.
I tied a loop of nylon webbing around one of the top 1 1/2" tubes across the
top of my arch. Attach a block and tackle. Have a harness made of nylon webbing that my wife made that fits on the engine and provides a D-ring at the top of the engine (15hp 2stroke Mercury).
Its a straight drop now from arch position to top of the engine when it is on the dinghy. Attach the block and tackle while in the dinghy, release the engine mount screws. Haul the engine up from the dinghy position. Board the big boat. Pull the lines of the block and tackle inboard by hand places the engine directly above the engine mount on the stern rail. Lower the engine into place, screw in the engine mount screws. Remove block and tackle and store in locker.
In calm conditions its a pretty easy task for one person. If a swell has come up then its useful to have another person on the big boat to help damp the swinging motion of the engine as the swell rolls thru.
sounds like you need to make a pulley with the sheave the radius of the tube. A small rubber/ureathane bow roller may work well, then fabricate the side sheaves to hang your lifting gear off of. ouila!
__________________ "I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard
Hi, I used a spare boom vang with a cam cleat. It is attached to the tube of my arch with nylon webbing. I can lower or lift my 8hp Yamaha from the dinghy to the stern rail by myself. Very easy setup. I'll take pictures tomorrow if you would like.
rope shackle, leather liner, smooth side of leather against the metal, rub in as much lanolin as it'll take. This is an old solution to an old problem, new materials dont supersede old materials, they just do different things
I know I am kinda late to the conversation, but another option you could try, and I did this on our old motor boat was go to a hunting/sporting goods store and buy a small gambrel. These are twin pulley contraptions that work fantastic for what you are thinking of as well many other uses on the stern area. A rope,strap, plummers tape work great and make it moveable. Just a thought I have used many times and will do so on our new (to us) boat.