Now you mention it, it's one of those battened sails from the period where the class was dividing into two thoughts about the sail issue. If I am not mistaken some went for the battened sail and called the new class "Sprint", omitting the "M" in the sail insignia
This (in hindsight silly and soluble) discussion was going on during the decline of the class, so if the collar-number matches with the sailnumber, this one -5671- could be one of the latest Monaco's built.
Mind I wonder if any Monaco's were built towards the end of production, with Sprint MI and Sprint MII having probably replaced them?
Seeing a bendy-boom and the absence of deck-cleats I presume it's a clean Monaco.
With the relative small amount of Minisails ever built it keeps amasing me how many keep turning up.