Reading thru lots of material and lots of brochures, everyone lists
deadrise.

Seems that the deckboats have a lesser degree of angle, (15 - 17degrees)
bowriders of shorter length have middling degrees, 18 -19 and larger
boats 23' and up, higher degrees.

So the larger the boat, generally, the deeper the vee, and less of an
ability to plane. (and also a smoother ride.)

What I can't find is where it's measured. Is there a standard, or is it
arbitrary based on the hull technology?

If that's the case, why bother to advertise it if it doesn't mean much.