This doesn't answer the question, but I find that I get completely soaked when I walk in the rain, and I get completely soaked everywhere except for my butt (which remains completely dry) when I run, so I'm not sure that angling the canvas would do anything. Just cover it so that it doesn't get wet at all...
SCIENTIFIC PROBLEM!!!!!
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Jan 23, 2010
0
#3
If the canvas' horizontal velocity is vc then the required angle is arctan(vc/vr) to the vertical.
Thus, if the canvas is stationary, vc = 0 and the angle is also zero whilst if vc = vrthen the angle is 45 degrees.
Don't go out untill the rain has stopped..
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I think it should be as vertical as possible and slowish, but not so slow as to be totally wet by the time you get back out of the rain.
The faster you go, the more raindrops you will run into.
On the other hand, if you went really fast, only one side would get wet.
I guess it could be tested like this. See how wet it is after going maximum speed through the rain and then see how long it has to stand in one place in the rain before it gets as wet as it would be at the max speed across through the rain. Then balance out the proportion of speed to time in the rain, for least amount of wetness. 
Jan 24, 2010
0
#6
Alternatively, turn the canvas edge on to the direction of motion and move it as fast as you like!
Great idea!
A television show tested this using an absorbent suit and a large room setup with sprinklers in the ceiling pouring water. The weight measured approximately the same. It seems running causes less water to hit the suit vertically, but more to hit horizontally. And the effect was equally proportional. I do not know the margin of error, nor the degree of accurary. The show was called Mythbusters.
Bump
There is a nice video about this interesting topic. Check it out. https://youtu.be/3MqYE2UuN24?si=W7Zymr0T-gx5hsr_
Have you ever wondered whether you would get wetter if you ran through a rain storm rather than walked? At which angle should you incline your head to minimize the amount of water that hits you? This puzzle asks the same question, but concerns moving an object through the rain: a museum’s large, precious Delacroix canvas.
To start, assume your museum’s canvas is of height H and side-to-side width W. Raindrops fall vertically at velocity vr . It is raining steadily and heavily and you don't want the canvas to get wet.If the canvas is waterproof on its very top surface (and the water that hits the top will flow to the sides of the canvas without dripping on it) but the canvas is equally sensitive to water in the front and back, how fast and at which angle should you move the canvas so the front and back receive as little rain as possible?