Bayliner 5.0 way under propped?

[kswiatk]

I believe I am having some issues with under propping on my Father’s boat. It is not the original prop, it was replaced about 11 years ago by a local marina. Not sure if they replaced with whatever they had or same as original. Also, not sure if they installed the wrong prop or has something happened to ours?

There is no vibration or anything noticeable while driving.

Boat

-2005 Bayliner 205 BR 21 foot length. 3300 dry weight with base engine, not sure if ours is base.
-Mainly use it for towing sports, top speed isn’t our necessity but would be nice to tow a skier at lower rpms

Drive

• Mercruiser 220hp 5.0 with alpha one gen 2 gear ratio 1.47

Prop

• Black Max 14.5 x 19p aluminum 832830a45

Performance

• 30mph at 4200 rpm, 35 mph at 4600 rpm
• When I go wot, engine begins to go into upper 5000s, but I don’t let it, don’t want to damage it
• Gets on plane very quick, but annoying to have to be revving so high for a water skier.

Is it possible something has happened to the current prop or has it always been under propped? It has been too long to remember before the switch. It just seems weird that the boat is so slow, some reviews say they get it up to 50 mph.

I have been thinking about changing to a four blade aluminum prop. Turning point props recommends a 14 x19 or 14 x 21 4 blade aluminum prop.

Does anyone have any idea what pitch to change to?

Also, does the prop hub need to be replaced when changing this prop?

 

[SkiDad]

sounds like either the tach is bad or set incorrectly. Suspecting the tach is set for V6 somehow. A 19p should get your close to 1:1 mph/rpm on your boat and would be the correct pitch for water sports.

 

[Scott Danforth]

your motor should have a 19P prop and with a 15 x 19P with that carbureted motor and drive you shouldnt be able to over-rev.

check the tach with a known good tach

 

[kswiatk]

That's good to hear. Will check the setting.