One of the best things about an Alcan/Alwest is the big windows that let the breeze flow through . . . . except when it is raining. The slope to the cabin sides will even let a straight down rainfall come in the windows on both sides at the same time ? There is a really simple way to solve this, that I came up with one muggy rainy evening several years ago and have been using successfully ever since. Simple Plexiglas rain deflectors (“awnings” I call them) can be temporarily attached over each window when rain threatens. The aft ones need to reach out around the aft corner panels (on an Alwest).
The forward ones reach out beyond the superstructure to cover the sloped window ends, but this works too.
At an angle of about 45 degrees these will protect the window for its entire height, in all but the heaviest downpours or cross winds. I did try larger awnings over the door and rear window, but these got in the way of entry/exit and eventually were abandoned. When the sun comes out, the awnings are stacked together and stored in a small compartment on the flybridge.