I don’t have a lot of hours n my 38E, but during sea trial and repair testing, it’s quite clear that our hulls are really full displacement hulls. You can add a lot of horsepower and large trim tabs and power your way to plane. If that’s what you’re looking for, this isn’t your boat. A Beneteau Swift 35 or 41 have the power and light weight to plane. I just enjoy hull speed. You’ll get about 2.5 miles per gallon on any engine you select at hull speed.
If it was a full displacement hull it wouldn’t be possible to exceed hull speed with any engine that would probably reasonably fit.
I don’t know this for a fact, but after 54 years of messing around with boats, to my eye the hull form looks a lot like the Wilbur 38. Performance seems very similar with the Wilbur 38 as well.
The Maine Downeast builders make many boats with similar hull lines. Deep forefoot, full built down keel, soft chine, transitioning to a flat after section. Very different from the hull form of a Krogen or Nordhavn.
“Semi displacement” is a spectrum, and this hull leans more into the displacement zone than semi-planing. On the other hand a hard chine and skeg type keel would lean more towards planing (like the American Tug hull form).
The Beneteau hull is really a more or less conventional full planing design, albeit with a very small keel seemingly solely for directional stability. The trade off is higher speeds with less fuel consumption.
FWIW the Wilbur 38 needs at least 450-ish hp to achieve a semi-planing running attitude. Those boats are sometimes powered with 800+ hp engines and can exceed 20 knots.
The Helmsman 38 hull seems to perform similarly. It seems to take at least 425 and more like 480 hp to achieve hydrodynamic lift which generates about 16 knots, and my 550 hp yields 17-18. All very similar to the Wilbur 38.
Of course fuel consumption increases exponentially once above the 7.5-ish knot hull speed. Doubling speed takes much more than double the amount of fuel.
It’s like the old hot rodder’s saying - ‘Speed costs, how fast do you want to go?’