I have been reading on this and am more informed than opinioniated now than I was a while ago. Notice I did not use the word smart !!!
I am convienced our boats are planing hulls by defination. It is a little subjective because the definations are not short and sweet so it is ever so slightly argueable. but I will re-cap the points I took away below that make me feel as I do.
A planing hull on plane will have the water that has been displaced, knit back together rearward of the transom, Check yes !!
A planing hull boat will actually require less propulsion once it actually goes up on plane and begins to slide across the water. " not necessairly more fuel efficienciey " and these boats do in fact plane on top and once there can be powered down below what it took to get them on top and stay there so once again this supports the planing hull.
Another thing I read on the engineering site was that Semi Displacment hulls rarely would go more than 16 to 18 knots. I assumed this to be under a typical horsepower to weight ratio. I believe every Marinette ever built would exceed that and go faster easily with more power.
If your particullar boat wont achieve this there might be something wrong with either the power plant not producing the needed power or you might have too much from marine growth holding it back but either way the hulls on these boats certainly are of planing hull design.
A good example is my 466 Bertram, when I haul it out for work and re-do the bottom it will always give me 25.9 on the GPS and is on plane. If I let it sit too much through the summer it will pull down around 21.5 mph.
466 Bertram FDMY, " Easy Rider "
1984 39 Marinette sedan, " LIBERTY ONE "
440'S 19x22 wheels, 710 HOURS