Newbie here....And I've got some questions

Thank you kindly in advance for answers, and advice.
I run a Volvo penta AQ125A with a 280 outdrive, 14x17 dinged up prop in a
15' fiberglass cobia charger bow-rider. I've owned this boat since March of this year, and I've had it on the water about 12 times. Seems to idle fine. Engine does'nt "cut out, or die at WOT. The problem I'm having is: The onboard Tach is reading, 3200 to 3400 RPM. The rated RPM for the engine is 4400 to 4800 max. I have changed the oil, plugs, wires, gas, ran carb cleaned through the carb, cleaned the flame arrestor, and water strainer. Old oil had no evidence of water, spark plug electrodes were all a tan color with no evidence of foul out, or lean operation. On the out drive, I changed the oil, and replaced the u-joint, and exhaust bellows. I took it out yesterday and test ran the boat with a hand held GPS to get an idea of how fast the boat runs.
Top speed, 36 MPH.
AVG speed was 34 MPH.
Engine RPM ~3400. Never over that.
My questions are:
Can a dinged up prop cause a loss in engine RPM, at WOT there by causing a loss of speed?
Is it possible the timing is off a few degrees? Maybe the distributor is not advancing all the way thereby causing the engine to not make it up 4400?
And last, Could it be the carb? It is only a downdraft solex single BBL.
I have not checked the compression, or the timing yet.
Thanks again for any advice or ansewrs.
Newboater

 

Can a dinged up prop cause a loss in engine RPM, at WOT there by causing a loss of speed?
Not that much if any.

I would check the accuracy of the tach before doing any thing else, as the top speed isn't that far off.

 

Once you are certain that the tach is correct, you might want to consider running a pro with lower pitch. I aould guess that a 14x15 or 14x14 would get you moving a bit faster. The 14x14 prop will get you up to 4000 rmp or so...

 

In order for your Prop to be bad enough to appreciably effect RPM, you would feel a definate Vibration. More than likely your Tach is not accurate, since it would take close to 4800 RPM, to get 36 MPH with a 17P and 2:1 Gear, which I believe is what you have.

 

Yes a dinged up prop will reduce your top speed . Very much so.

Beg, borrow or steel a new one.

A prop is your contact with the water. If you've "dinged" it, then yes it will affect everything, top speed , fuel consumption , pulling, everything.