hmmmm - so a 9.8hp on my tender (3m) is a little excessive eh Jack?
to me displacement is displacement - anything else is technically planning although some hull forms are not designed to give the necessary lift to plane cleanly and are clasified as semi displacement (semi planning!) - on the other hand they don't have large resistance humps either so work well at medium speeds.
shorter the waterline length of a boat (or object) and the lower the speed it must be planning or it sinks as a result of it's sternwave. simple fysics.
520 will, based on a mwaterline length of 4.8m, have to be planing at 5.57 knots or sink - well the recently modified figs actually suggest that it could survive up to 6.13 knots but ...........
Phaeton can get to about 8.5 knots before it hits R1 and needs a huge injection of power to go faster (and over the hump).. Fortunately the turbo comes in at 8.2 knots.....and delivers that power! I am fully planning at 10 knots but don't get the full hydrodynamic effect from the hull untill 14knots normally laden - at which point I am properly (fully) trimed out at the drive as well.