I disagree about the structure of the two boats being equal. A lot of the Oceanis series had rolled out deck joints where as the Firsts had through bolted inward facing flanges. The Firsts have tabbed in bulkheads, while the bulheads are either tabbed in with narrower fillets or glued into the Oceanis and ''number'' series. Chain plates and attachment points look beefier on the Firsts. The internal framing is closer spaced on the First, or so it appeared comparing several similar sized models boat for boat at a boat show and at Annapolis Yacht Sales open house. Climb down into the lazarette where this stuff is really pretty visible.