There is a brackets that looks like a "V" with a bolt through the top of the "V" section which secures it to the mast and on which it pivots. It's got a vertical hole in the bottom of the "V" and there is another bracket with a horizontal hole in the same place near the bottom of the "V". It kind of looks like it would be where a normal boom vang might be but there is no need for a boom vang on this design. It obviously pivots with the mast and must have some function. Thanks for your assistance.

Probably need to share more details on this. What kind of boat is it? Do you have diamond wires?

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Rob
OKC
Pile of Nacra parts..
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post a pic and we can tell you