The dog is there for scale. It's an inch thick(which is much thicker than Daisy would be if it fell on her). I think it came out of Thunderhead.

The pivot pin hole is lower right and the appendage is the lever connected to the lifting linkage. From the pin to the outer hole on the lever, you can see the large arc of it's travel and a sense of the size of the centerboard trunk.

With the sharpened leading edge, it reminds me a little of a guillotine.