What is this metal rod for?

[SV Siren]

I have on of these on my new to me GOB, and never knew what it really was....thanks guys for answering a question I had not gotten to yet....I will be leaving it onboard. The PO when asked gave me a different answer which I thought a little odd and farfetched.

[Paul Mazza]

I know this is a really late response but I'm a month behind on the forum. I believe all the comments about the rod preventing the deck from lifting, delaminating, etc are correct. I also own a 1979 Endeavour 37 A plan, and what is unusual about them is the A plan doesn't have a main bulkhead anywhere near the mast. No V berth and a forward dinette. My boat had a metal fitting attached to the top of the rod, on the cabin top, that is used to attach the factory installed boom vang. If you search the web, you'll see most of the E-37's have their vang attached there. If you havent already I suggest you look into the Endeavour Owner's Forum. Lots of useful info there. By the way, where was the leak?