Go Back  Offshoreonly.com > Technical > General Q & A
RPM question >

RPM question

Notices

RPM question

Thread Tools
 
Old 08-07-2013 | 11:17 PM
  #1  
Thread Starter
Registered
 
Joined: Oct 2012
Posts: 81
Likes: 0
From: Flint, Michigan
Default RPM question

Hey guys, So while replacing my water pump on one of my motors today i ran across the info stamp on my motor and read that its only rated for 4200-4600 rpm's.. however with my current prop set up im spinning at about 5-5400. so am i correct in thinking i need to reprop my boat? im currently running a 20p 3 fin on both CW rotating drives. i do 64mph with that set up. If i were to go to a lets say 23p? would that bring down my rpm's? and increase the speed slightly or will that decrease the speed? thanks!
88Force265 is offline  
Reply
Old 08-07-2013 | 11:27 PM
  #2  
Fenderjack's Avatar
Pirate of the Chesapeake
 
Joined: Aug 2006
Posts: 4,330
Likes: 0
From: North Point Creek, Md.
Default

You shouldn't be turing that much on a stock older set up. Yes it can do it, but not good to do it for long. It should bring the speed up if the engines can spin them. 1'' in pitch on a prop is usually good for about 200 RPM drop.

John jr
Fenderjack is offline  
Reply
Old 08-07-2013 | 11:36 PM
  #3  
Thread Starter
Registered
 
Joined: Oct 2012
Posts: 81
Likes: 0
From: Flint, Michigan
Default

Bought it with that set up just trying to get her "right" and finding out all the info as i go. i dont see a 23p being too much of a problem with the 350mags, that should bring me down to roughly 4600rpms with the 200 drop math. anything i should look out for etc? any suggestions on what to do Thanks again!
88Force265 is offline  
Reply
Old 08-08-2013 | 07:31 AM
  #4  
Knot 4 Me's Avatar
Registered
20 Year Member
 
Joined: Jun 2005
Posts: 8,407
Likes: 797
From: Central IL
Default

I'd first determine what my drive ratio is and verify my tachs for accuracy against a shop tach. Then you can better determine what pitch props are appropriate for your boat.
Knot 4 Me is offline  
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



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

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.