I only picked up about 200 rpm and lost 2-3 mph. I'm only getting about 32 mph out of a boat/motor combo that should do 50ish
What I don't get is how engine issues have any bearing on speed at a given rpm. If the engine is turning 4800 I should be getting 42ish mph per the calculation. I could see that I would be limited in rpm but don't understand how that has any correlation to the math?
The numbers aren't adding up.
You say you gained 200rpm so that should put you at 4800, then you say the speed dropped, and you are getting 32mph. Well as I said those rpms, gear ratio and some slip should yield approx 42mph.
Is the speed from a GPS or the water pressure speedo?
As asked before, is the tach set correctly? It reads alternator pulses, not ignition pulses.
BTW your engine is supposed to be running between 5000 - 5500 rpm, that would put it around 50mph, but...
Either your engine is not up to snuff, your boat has gained a lot of weight, the hull has issues(hook)
Are you trimming the engine up at higher speeds?