The three static ventilators on the H33 have a stainless steel shell but underneath is a plastic structure. On my 79 boat, all of the ventilators had to be replaced, the plastic was just gone from the ultraviolet. I believe that other Cherubini designs and perhaps other boats as well have this ventilator. (See photo) The cutout hole is 4". A while back Jim Logan wrote a post telling about replacing the vents on his H33 with the Beckson vent-o-mate with a direct replacement possible. I just got around to buying a couple of these inexpensive vents and have found that Jim was exactly right. Not only do they fit, they are basically identical even though the originals were made in Sweden and the replacements in Taiwan. Anybody with a 20 year or so old vent that looks like the picture may want to consider replacing with these vents. I got mine from West Marine but there are probably other sources as well. Change out is as near a no brainer as comes with sailboat maintenance since all of the screw spacing is exactly the same. Jim said that he replaced all of his in an hour. I'm not that fast but it still is very little time. Best of all the original stainless shells can be replaced for the new plastic ones retaining exactly the original look.
