Diameter

[AZSenza]

Ok, I know everyone talks about pitch and blades but what about diameter? I'm currently running a 14.25X17 stock Aluminum Volvo on a 07 SX pushed by a 220hp 5.0GL in a 18'6" bowrider (Larson 186 Senza) I guess my question is what difference will it make to go to a higher Diameter? like a 15 or 15.25. (Looking at a stainless)

 

[steelespike]

Re: Diameter

Diameter is a product of propeller design.You generally wouldn't buy a prop
with diameter as a primary selection criteria.You might consider diameter for certain specific problems or aims.Of course there is the clearance issue as well.Generally all else being equal the larger diameter is more difficult to turn.
Usually if you started with a 14.25 you would stay in that area maybe 1/4 either way,which again is a result of prop design.
The experts may be able to give you some tips about diameter selection.

 

[AZSenza]

Re: Diameter

Thanks! Thats the kind of asnswer I was looking for!
I'll stick within mfg's reccomendations for that then. They reccomend a 14.75X21 aluminum, I might try a 19 SS

 

[steelespike]

Re: Diameter

Before making a prop selection give us your present max rpm and speed
we have your prop size at 14.25 X 17. Seems way small.The 21 is probably better but you should give us your typical load and activities.

 

[AZSenza]

Re: Diameter

I'll take readings today. Usual activities are cruising and pulling small (my kids) skiers. They have tubes including a 4 person, a wake board and skis. The boat holds 9 persons or 1400 lbs. We will have the people but NEVER that much weight! She gets on plane QUICK but feels like its starving for fuel up top, say around 4000 RPM. I'm going to put a 4 barrel carb in place of the 2 barrel to try to get the top end back.
-Thanks

 

[AZSenza]

Re: Diameter

Ok, I ran it hard yesterday, she yanked my 165lb son out of the water and planned great BUT, just cruising (MOST of what we do) full speed was 55MPH at 4900 RPM WOT, I'm going to be putting a 4 barrel carb on it. I was wrong about the prop size, its a 14.8X19 aluminum. I'm thinking a 14X21 Stainless to get the RPM back down a little and still keep my holeshot. Any comments???

Larson 186 Senza 220Hp 5.0L about 3200Lbs loaded.