Here's another few data points.
1. Sailfish 220 basically a 23 seacraft hull - 18 inches tested at 4450lbs with a single Mercury 150. It's turning a Rev 4 SLOW arse bulldozer prop. Enertias are WAY WAY faster.
http://sailfishboats.com/wp-content/...F10032013Z.pdf
2. Capt Bone alerted me to a 25 Bertram owner that repowered with this same engine and it reportedly hits 32 knots (36.8mph)
3. 1987 Mercury 175hp powerhead on my 200mid and lower pushed my 23 to 43mph.
https://www.youtube.com/watch?v=jg7cdv1w1vE