Tom,

Not sure what you mean by offshore. The photos of the A-cat worlds in New Zealand show some large seas they're racing in. I've seen videos of A-cats sailing in >20knot winds with whitecaps on top of rollers. I've never sailed one, and know one would suggest the A as a Worrell boat. But they certainly appear to handle any conditions you'd sail an I17R in. Skipper skill is the bigger issue.