I have a 250 Sq foot spinnaker I have been using on my h-18 that I bought new from Randy at Spring Fever this past year. I selling it. The pole probably would not work on a 19 MX but I would think the chute would. It is bigger than the f-18 chute. I-20 runs a 270 so I would guess that a 250 sounds about right for the 19MX. It is a cool orange and black pattern. I attached a picture of it on its way up. It was light air. This was the Around Aquidneck race. We launched it and had to untie the sheets, untangle them and retie them and still went about 10 miles ahead of a few Inter 20s and Nacra 6.0s who had started with us. They only passed us when it came time to drop the chutes. It is made out of airex and was 810 new. It has about 5-10 uses on it.
