That might be it, it was found on a 44’ FP with a huge mainResembles a Cunningham hook. Unsure the purpose of the orange retrieval lanyard, though.
That’s what I was thinking, it would be pretty open for a clevis hook though. It looks like something that one would unload cargo with. A bridle below (of chain?) and the crane cable above with an eye splice. Pull the release when down and it is free of the cable.
As Miracle Max said: "Good luck storming the castle!"North of the Puget Sound folks tend to use wooden "Bull Rails" to secure your boat at the dock. Coming up to the dock you can not just throw a loop over a cleat you need something to grab the rail.
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Here is one solution. The "Claw Carabiner Grappling Hook".