An unused genoa with a 10'foot came with the 16 I recently bought. That's a mighty big sail for a boat with a 4 foot J dimension (name?). Comments? Experiences?
Well, the standard J for a compact 16-1 was 4.5 feet. There were a lot of 155% Geneos made, J=7 ft±.
If yours has hanks on one edge, then it was a monster that someone made or tried to adapt from another boat. I have seen some spinnakers made, so if no hanks, that might be what you have.
Has plastic twist-on hanks. Shape fits the angle between forestay and deck; leach is the right length. Made by Johnson Sails. From what you write, probably a custom order by someone over-ambitious or sailing in the Horse Latitudes.