Need an advice on a prop for 1996 Bayliner 2355 Cierra

Acuario

Cadet
Joined
Aug 9, 2010
Messages
29
I have a 21 pitch stainless steel 21 pitch prop to put on but the boat has 15.25 X 15P EOM? can i use this 21 Pitch pro and will be the differences?
 

eavega

Lieutenant
Joined
Apr 29, 2008
Messages
1,377
First question you have to ask yourself is, how does the boat run now with the 15P Prop? Does the motor run within its specified WOT RPM range when correctly trimmed and lightly loaded with the 15P? You don't mention the motor, so we can't tell you what the recommended RPM range is for your rig. In broad strokes, if you step up to a 21P prop, you will drop your RPMs significantly; like on the order of about 1000 RPMs. If you are within your recommended RPMs with the 15P, then the 21P will not do a thing for you except to lug your motor and cause it to die an early death. You would also have a harder time getting your boat up on plane.
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
What is the top RPM your engine can attain at wide open throttle with normal load now?
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
If it is operating within its rated rpm range with the 15 the 21 will be sluggish out of the hole probable;y won't reach rpm range.
If you have the prop give it a try.
 

jestor68

Commander
Joined
Jun 12, 2012
Messages
2,308
Depending on which 5.7L motor you have, the rpm range is 4200-4600 or 4400-4800 for the 250 EFI version.

The "standard" prop would be in the 17-18 pitch range with the motor developing full(like new) power, according to the Mercury prop selector.

A full throttle test run is necessary to evaluate the current(15 pitch) prop.

A 21 pitch is most certainly too much for your 18 year old motor.
 
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