John, it's a slotted opening for each screw head, so the vent slides and locks into place. The larger opening fits over each screwhead in the toerail and when shoved in place the slot draws it tight. So just tap it a bit fore and aft. I have mine off every season when varnishing and I always check that the toerail is sealed around the opening and and clean the screen while it's removed. Bill Mulvey, 1973 Commander 41

Congratulations! My '73 41 was my first boat purchase . . .30 years ago. Still giving it all the care I can.

My 1972 41 has hydraulic steering and the helm had become very stiff. I mentioned it to the marina's owner, who incidentally has been this boat's sole mechanic since it arrived new from ChrisCraft, and he said, "follow me." He sprayed WD40 on the rudder arm fittings beneath the aft head and told me to go up and spin the wheel. That's all it needed. Problem fixed. The next owner can repeat the process in 2072.

A 30 year replacement regimen vs a 2 year routine is quite a range. I suspect that an annual engine hour average could be a factor. My 427's only run 30-50 or so hours a season.

Robert Bradley . . . similar experience this past summer on the lake . . . port engine was running hot, with little warning, and a the plastic sheathing on a shift cable melted from the heat because it was near an exhaust riser. Smoke, no fire. I've always had the habit of checking the exhaust for water while warming up, but that's not enough. Lacking any records of pump service, the marina replaced the impellers on both engines the next day. Not certain about the boat's first 20 years but I know for certain that they had lasted throughout my 30 years. New ones won't last that long. This is an important post. Your experience is cause for concern. Glad it worked out for you.

Chris Orphal . . . I agree with you regarding toerail replacement projects. It demands a a lot of measurments and woodworking skills . . . with expensive lumber. Mine are mahogany so there was a little rot here and there and fortunately I only had to replace a few sections. Machining the openings for the fuel fills, vents, deck cleats and stanchions was a challenge for this novice.

Fortunately 'Challenger' has the benefit of inside winter storage, so as soon as it's warm enough the mahogany toe rails and wood trim get a light sanding and one annual maintenance coat of Epifanes. It's easier than stretching it to two years and film failure and risking the task of taking it down to bare wood, filling the grain and laying on 4+ build coats to bring it back. It's all about UV protection and an intact film. Plus, varnishing can be relaxing. :-)

In a previous life I taught web design . . . this gets an 'A'