Wooeee. I had a 1999 Hunter 380 and I replaced the Dorade Cowls for shinny stainless ones, I believe, bought from this web site. All you had to do was take the old ones off, clean the fiberglass beneath them, then caulk and insert the base and then screw them in. Maybe I bolted them in--I can't remember. Either way it was easy. Then you screw in the Dorades and tighten a set screw. Wow, did they look good and they really improved the looks of my boat. I think they helped sell my boat three years ago. She looked good!
As an aside to some of you. Back in the 1930s I believe Sparkman and Stevens designed a wood boat which was named Dorade. The design team came up with a box that was on either side of the mast that had cowls. But the entrance to the cabin was aft of the cowls so no water would get into the cabin. It was a unique and different solution to getting air into the cabin. From that time, devices that allowed air into the cabin without all the water were essentially called Dorade vents.
Another point to make. If one has Dorade vents, one cowl should fast forward and one cowl should face aft. Wind going past the aft facing one sucks air out of the cabin while of course the one facing forward pulls air in. Aim both forward and you actually can stop the movement of air into the cabin.
Dorade was a beautiful full keel cutter yawl which for a number of years sailed out of a camp for kids on Orcus Island in the San Juan chain. She earlier had won a cross Atlantic race and was the beginning of a series of S & S designed, smaller, lighter sailboats....although today she would be considered more of a heavy boat. She was beautiful under sail.