With the boat out of the water and waiting for launch, I finally had time to do some measurements on my 1980 Prairie 36.
It wasn't easy. I measured from the ground to the waterline in several places, then from the waterline to the top of the gunwale, then transferred that to the top of the crown on both forward and aft trunk cabins. From there I could measure height.
I was helped by the fact that the top of my rails on each side were exactly level with the top of the aft trunk cabin top.
I also dropped a string to the ground fore and aft to measure length.
I got some surprising results, and some I expected. Length of the hull is 36'3". Adding the swim platform gives me a LOA of 37'1". NOTE: I'd removed the pulpit to fit in my slip, so unless you mutilated yours the same way, you'll need to add that for your LOA.
It turns out the alleged draft of 3'3" or 3'6" that I've seen published is wrong. It's about 44 inches, or 3'8". Admittedly, the ground could be uneven by an inch or so, but it was still a bit of a surprise.
Air draft was also different from what I've read. Waterline to the top of the mast is 18'11". Add on 3" for my masthead light and total is 19'2". Pretty close to what I thought, since I always check when going under at low bridge.
The top of the Bimini is about 15'10". The top of the windscreen is about 12'9". I thought I read somewhere it was more like 14'.
Anyway, I figured I'd post this here for posterity, in case someone else always wondered this stuff about their Prairie 36.