Having moved my Cal 29 with a 4Hp outboard and now the Atomic 4 is back in and healthy
At 8000# and not all that slick of a form the 4HP moved it at 4.5 knots
The A4 will take it up to 6+ knots but the stern squats so bad we don't go much over 5 to 5.5 knots at about 1400 RPM
So i can conclude that as you try and go above 4.5 knots the HP needed goes wau UP
The boat will sail that fast in 5 knots of wind BUT to reach 7 knots it needs to be in the twentys
One would think that a boat could be sailed or motered pretty close to the same top speed yes?
In your case are you saying that top speed sailing is 7knots and motoring is 6knots.
If so is that because you have the wrong prop?
The A4 certainly has more than enough HP.