[Blue_Heron]

So, just to complicate the issue, don't forget to factor in the hydrodynamics of the hull at displacement speed. Most of what I have to say here is from Dave Gerr's "The Nature Of Boats". But I've probably got some of it wrong because I loaned the book to someone who didn't retern it, so I can't check.

Every boat has a "hull speed", the most efficient speed for the hull to travel when it's in displacement mode. Hull speed is mostly determined by waterline length. When a boat moves in displacement mode it pushes a bow wave in front of it and drags a stern wave along behind it. This basically sets up a standing wave with a wavelength roughly the same as the waterline length of the boat.

The speed that waves move through water depends on their wavelength. Waves with long wavelengths travel faster than waves with short wavelengths. A short hull sets up a short standing wave that moves slowly. A longer boat sets up a longer standing wave that moves faster.

Hull speed is the speed at which the hull is in harmony with the speed its standing wave wants to travel. If you try to push the hull faster than hull speed, it tries to climb the bow wave and the bow of the boat rises. Because the boat is now trying to run up hill, it takes a lot more thrust to maintain this faster speed. Given enough thrust, the hull climbs over the bow wave and is then traveling at planing speeds.

So, in a nutshell, the kicker best suited for the boat is one that pushes it at hull speed while it is running at its most efficient RPM. Unfortunately, I have no idea what this is for a Seacraft 20.

Dave