Go Back  Offshoreonly.com > General Discussion > General Boating Discussion
More prop selection questions >

More prop selection questions

Notices

More prop selection questions

Thread Tools
 
Old 04-08-2011, 06:10 PM
  #1  
Registered
Thread Starter
 
Join Date: Apr 2010
Location: Lake Travis
Posts: 724
Likes: 0
Received 0 Likes on 0 Posts
Default More prop selection questions

If you keep the pitch the same but decrease the number of blades what outcome can you expect?

Easier to turn the prop, so you should plane faster and be able to turn more RPM? That should translate into a little more top end, right? Or am I missing something?
Crossett is offline  
Old 04-09-2011, 02:42 PM
  #2  
Registered
Thread Starter
 
Join Date: Apr 2010
Location: Lake Travis
Posts: 724
Likes: 0
Received 0 Likes on 0 Posts
Default

no one?
Crossett is offline  
Old 04-09-2011, 02:47 PM
  #3  
Registered
 
Join Date: Dec 2004
Location: Newbury Park Ca
Posts: 219
Likes: 0
Received 1 Like on 1 Post
Default

Not that simple , many variables come into play , ie : propshaft depth , steps or no steps , weight , power etc .
HALLETT FAN is offline  
Old 04-09-2011, 02:51 PM
  #4  
Registered
Thread Starter
 
Join Date: Apr 2010
Location: Lake Travis
Posts: 724
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by HALLETT FAN
Not that simple , many variables come into play , ie : propshaft depth , steps or no steps , weight , power etc .
I'm not able to spin my engine as high as I should be (4200 rpm ish). I assume that it's because the prop is too much for the power that it makes. My prop is a 23P 4 blade. I found a used 23P 3 blade for $100. Would it be worth it to buy it and swap them out? I'm looking for a little more top end.

I don't know propshaft depth, it's a factory 24 Outlaw evidently the X dimension on them is pretty low. No steps. Boat weighs about 4000 lbs. Stock 330 hp 454.

Last edited by Crossett; 04-09-2011 at 02:56 PM.
Crossett is offline  
Old 04-09-2011, 07:33 PM
  #5  
Registered
 
Join Date: Dec 2004
Location: Newbury Park Ca
Posts: 219
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by Crossett
I'm not able to spin my engine as high as I should be (4200 rpm ish). I assume that it's because the prop is too much for the power that it makes. My prop is a 23P 4 blade. I found a used 23P 3 blade for $100. Would it be worth it to buy it and swap them out? I'm looking for a little more top end.

I don't know propshaft depth, it's a factory 24 Outlaw evidently the X dimension on them is pretty low. No steps. Boat weighs about 4000 lbs. Stock 330 hp 454.
With that weight / horsepower / drive depth combo , a labbed 21
mirage may be the way to go
HALLETT FAN is offline  
Old 04-09-2011, 07:46 PM
  #6  
Registered
 
Join Date: Feb 2010
Posts: 62
Likes: 0
Received 0 Likes on 0 Posts
Default

If everything is the same except the number of blades I think increase of 250 ish rpms
mindog20 is offline  
Old 04-10-2011, 06:34 AM
  #7  
Registered
 
Join Date: Apr 2009
Location: Denmark and hopefully some place nice
Posts: 1,852
Likes: 0
Received 1 Like on 1 Post
Default

In most cases, a 4 blade will plane off faster than a 3 blade. What engine are you running? We need to know the operating range of your engine. What is the 3 blade you are looking at - make/model? The same goes for your 4 blade. From 4 to 3 blades will give you between 150-200 rpm's. Maybe more, if you also decrease dia. I would try a 21 Mirage+.
A.O. Razor is offline  
Old 04-10-2011, 07:01 AM
  #8  
Registered
 
Join Date: Aug 2006
Posts: 4
Likes: 0
Received 0 Likes on 0 Posts
Default

Also consider the diameter of the prop, larger diameter=less RPM. Opps just read the post above mine......
04harleyboy is offline  
Old 04-10-2011, 07:01 AM
  #9  
Registered
 
Join Date: May 2006
Location: Jackson, Mississippi
Posts: 448
Likes: 0
Received 0 Likes on 0 Posts
Default

I believe a stock 7.4 330hp should operate at about 4600 rpm. A mirage plus will carry the bow higher than just a mirage.
pitts1313 is offline  
Old 04-10-2011, 07:08 AM
  #10  
Registered
 
Join Date: Oct 2000
Location: Lakewood, NY, USA
Posts: 3,482
Received 317 Likes on 174 Posts
Default

Based on conversations I have had with owners of Outlaws, they run better with 3 blade props.
Padraig is offline  


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.