Determining Air Draft (Boat height above water level)

Yes, the literature is useless. Others will have other ideas I'm sure, but here's how we did it. We measured a boathouse height from the water. Pulled the boat in, measured clearance. So our air draft was the height of the boathours opening less the amount we cleared it by. You can do the same under bridges that have accurate markings, note the word "accurate" as some don't, so I'd select more than one to check. We've double checked our boathouse numbers with bridges.

Just as you need to know draft at different loads, make sure you take loads into account on air draft. This in addition to knowing it with all different equipment and height permutations.

Just lay a fishing rod across the hardtop where you can lay the rod verticle with a bobber on it and drop it down till it hits the water, then take it on land and measure it......if something sticks up above the hardtop measure that from the hardtop to the highest point and add to your measurement.

For RV's I use a laser level and large telescoping height pole. (Home Depot or Lowes)

Could you use your docking plan or general arrangement drawings to calculate the air draft while using a pair of dividers and the measuring scale on the drawing for the vessel and then add it all up?

A boat without even 1 fishing rod? Sacrilege! The measuring tape works, but I've found with all of the angles and stuff sticking out, sometimes harder to get an accurate measurment on some. EVERY boat should have a small plackard on the dash with the air draft.