Smaller Diameter...Same Pitch

[Crazy 8]

Im currently running a stock aluminum 15x17 RH on a 1986 Bayliner 2150 cuddy with an AQ125B Penta 270 WOT is 4800 (I think), thinking about going to a 14.5x17. Tend to have several passengers n pull a tube. Whats everybodys thoughts/recommendations on prop change?

 

[steelespike]

You'll have to school us in Volvo nomenclature.
Diameter is not usually a primary consideration for improving performance.
A 1/2" decrease in diameter may get a slight improvement in hole shot.
Maybe slight increase in rpm.You need to reduce pitch.How much depends on your present performance.
Get us a lightly loaded wot rpm and gps speed.

 

[Crazy 8]

Will do...once I get back in town here in a few days. AQ125B is the engine model aka 2.1L 4 cylinder. 2150 is the bayliner model aka 21'. Penta 270 is the outdrive.

 

[Bondo]

Ayuh,.... Welcome Aboard,....... Are both props from the same manufacturer,..??

Diameter plays more into blade design, 'n size, Vs: pitch is much more important to controlin' motor rpms,...

 

[Texasmark]

I guess you are loading up what you have. Less pitch and more diameter is where you need to go or up the blades and follow instructions herein.

 

[Crazy 8]

@ bondo I believe both props are michigan. Factory specs call for a 15x17 RH. @ steelespike the current prop is pretty beat up feom the previous owner so any reading I get will be skewed. Fastest ive had her was around 32mph with only 2 people onboard.

 

[steelespike]

Do you know the rpm at 32 mph? From my verity limited info I'm guessing the max rpm is 5000.?
I have 7 or 8 pages of various motor brands rpm and gear ratiosNothing even close to your setup.
I know the AQ125 is a motor but my limited info indicates it is not necessarily 125 hp.I know
the 270 is the outdrive But the key gear ratio is a mystery to many of us.If you look on the out drive
it may be stamped or on a label. Is the 15 X 17 a factory spec standard prop as apposed to that
that may be suggested for water sports or heavy loads?

 

[Sea Rider]

If PO is still available, ask if current prop was delivered with that engine and if performed well with a lightly loaded boat, if so, should be a medium pitch starter prop.

Happy Boating

 

[Crazy 8]

@ steelespike the aq125b kicks out a whopping 110hp lol...gear ratio (I believe) is 2.15:1 & the 15x17 is the factory spec