Re: 21 foot very slow hole shot, prop to big?
no both props are in excellent condition.
And it is not impossible as I am looking at it and I went to the lake and recreated it, exactly.
I have been a professional marine mechanic for a good part of my life, although on larger vessels.
I have all the diagnostic tools to do this with a high amount of precision.
Now, lets think this through a bit, and not just can't happen, sorry it did. There are many more interactions going on here.
I was looking a the torque curves for the motor vs hp. In the case of this motor I was behind both curves at 3000 rpm. The boat was just starting to hit the curves when it ran out of power due to load with the 21 prop. With the 17 the engine easily got on to and well into both the torque and hp curves.
This engine specs out like new with compression etc. However, and I did state this before I am at 4300 feet, which is a whole different ball game than sea level. It was hot out which makes the air less dense as well.
as the boat transitions from lets call it resting or semi displacement to planing the bow on this boat comes quite high in attitude, exposing the maximum drag profile. With the 21 prop it took 15 or more seconds to come to plane. With the 17 the attitude of the boat is fatter making the step transition much more efficient and much faster IE 2-3 seconds.
If the leg had a high altitude kit in it this would be less problematic.
So you see the observed conditions can happen, and can exist.
I think that a better statement would be, under normal conditions , at standard temperatures and pressures, we would not expect to see this type of result, however, there are other dynamic forces at work that can change the situation.
just for thought