I'd say it's definitely not the Ironsides. Your photo shows what I guess I'd call a large fin keel with integrated ballast in the leading edge -- whereas the Ironsides has a bulb keel with the ballast attached to the bottom end. From the label on your boat I suppose the previous posts may have identified the right source, but I don't see anything like yours offered in their site right now.
There are published antique designs that are very like your boat... such as this one called 'June' that's probably the wrong size but shaped much more like yours
