If it's has only been used a couple of weeks a year...it sounds like you might have found a cream puff...look on the transom and see what the serial number is...that should tell you what year it was built...it is encoded in the number...if everything is in good shape you could have a great cat on your hands.
Think of the Supercat 17 as an SUV of the cat world...race or just for fun... one up/two up/small family... true beach cat...no boards, yet tacks and goes to windward surprisingly well... equally at home on the ocean or lake... loves rough water... built nearly bomb proof without being excessively heavy (325 lb. I believe)...Probably the most pitch pole resistant 17 foot cat ever made...LOL.
I had a 1981 (or was it 82?) Supercat 17 built by Boston Whaler that served me faithfully for years. As far as I know, the hull itself (other than bringing the construction materials up to contemporary standards, and then some..)is identical to the new ARC17. Even with the old style sails the boat is no slouch.
Seems like the only complaint I read about this boat is that its P.N. is too high for as fast as it is...LOL...more boats wish they had that problem

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Regards,
Bob