Thalassa has six cowl vents, each about 15 inches high. Four are mounted on dorade boxes, one on the aft hatch, venting the lazarette compartment, and another on the forward deck, venting the chain locker and forward cabin (if the chain locker door is left open).

My best guess is that the vents were originally painted white on the outside and red on the inside. Red on the inside is traditional, but supposedly there is a functional aspect, too. If it were night time and a vent were facing aft, toward the helmsman, then any white light shining up into the vent from the cabin would reflect off the red -painted inside of the vent. Thus, the light seen by the helmsman would be red, which is less disruptive to night vision. In Thalassa, however, it is not possible for light from the cabin to shine directly into a cowl vent due to the configuration of the dorade boxes.

Winter is a good time for projects that can be done in the workshop, so I began cleaning up the vents and their mounting hardware. Some of the paint on the outside was chipped down to the metal, and the rest had to be removed by a combination of scraping, sanding, and application of chemical stripper.

After many days and hours, I finally got them down to the bare metal. It seems that they were bronze with a chrome-like coating on top.

I also cleaned up the mounting hardware, which was much easier because it was not painted at all.

I did some research into how to paint metal. It all starts by sanding, then painting within an hour, leaving little time for the metal surface to oxidize. I started with one coat of Interlux Interprotect 2000E, which is a two-part barrier coat primer, which for some reason is the best way to start here.

I followed up with a coat of Interlux Epoxy Primekote, which is a two-part primer that I’ve used before, and will use many times again.

Sanding between coats is essential.

I painted the outsides with Interlux Perfection (off white), but first had to tape off the boundary between the inside and out.

I devised a way to hang the vents from nails while various finishes dried.

The color looks great, but I had some issues with drips and dust. These issues are much easier to address while painting outdoors, so I gave the vents one more round of sanding and moved on to another project that can be done in the basement workshop–teak cockpit grates: