There should be a piece of SS at Bow at the water about 3" x 4" that the bob stay would attach that looks to be missing. I am guessing the year would be in the 70s. The mast is deck stepped. It looks like the head sails were not up. Just looked at mine and there is two vertical post on either side with a bolt that goes through the rear end of the Sprit (bow pole) that would be the pivot point and then the Sprit would be part of the inter forstay and the inter head stay my have keep the mast up.