Go Back  Offshoreonly.com > Technical > Prop Talk
What pitch???? >

What pitch????

Notices

What pitch????

Thread Tools
 
Old 06-04-2007 | 04:04 PM
  #11  
throttleup's Avatar
Registered
 
Joined: Mar 2002
Posts: 5,143
Likes: 1
From: Cajun Country
Default

If you prop for 4600 you will expoerience the best cruise speeds the boat has to offer. If you prop for 5000 RPM at WAOT then you should experience the top end. The power band of your motor is 4600-5000. If you fall below 4600 then you would be lugging the motor, consuming a lot of fuel and taking life off of your motor. So if you were to go to a 21P then you would loose 400 RPM putting you at 4200 RPM which is NO GOOD! So to answer your quetion you should not go to a 21P Mirage Plus as you don't want to fall below the 4600 RPM at WOT.

Julie
throttleup is offline  
Reply
Old 06-05-2007 | 09:37 AM
  #12  
Sonic30ss's Avatar
Gold Member
20 Year Member
Gold Member
 
Joined: Oct 2002
Posts: 1,237
Likes: 165
From: SWFL
Default

Originally Posted by prosno
Well Dave unless somethings wrong with gps or tach thats what I have, 4,500 - 4,600 rpms and grs says 40.
I know nothing about this model boat so I dont even know what its capable of. I'm not looking for total top end cause I'll be pulling my kid on a tube at times and cruising around the rest of the time. But in my opinion 40 at that many rpms is not good for all around.
Just a thought, make sure your GPS is set to MPH not Knots
40 knots = 46 MPH. And congrats on getting back in the game, maybe we'll see you on the river, happy boating
Sonic30ss is offline  
Reply
Old 06-05-2007 | 10:16 AM
  #13  
Pat McPherson's Avatar
VIP Member
 
Joined: Oct 2002
Posts: 5,246
Likes: 3
From: Ivoryton, CT
Default

Originally Posted by fredefox
Better double check your engine. In 1987 Merc called the 7.4 (300 prop shaft hp) a Mag. It was not the 365hp mag, if the boat came with an alph drive. RPM for the engine is 4200 to 4600. 23 foot Boat and 300hp will not pull a 21 pitch. 17 stainless mirage plus likely to be good beginning point.
Yup, 17p Mirage plus...
300HP at the prop, 1.3 Alpha drive.
The boat should top out at 50mph.
__________________
Patrick
Pat McPherson is offline  
Reply
Old 06-05-2007 | 07:36 PM
  #14  
Thread Starter
Registered
 
Joined: Nov 2006
Posts: 284
Likes: 0
From: Wallingford, CT
Default

okay I checked a few things today, engine is 454 330 hp, outdrive is geared 1.47 and is a rebuilt lower unit. Going to mess with it this week end I hope and write down all results. Thanks a bunch guys, Dave I hope to see ya on the river, gotta post some pics of this thing soon.
prosno is offline  
Reply
Old 06-06-2007 | 07:23 AM
  #15  
Pat McPherson's Avatar
VIP Member
 
Joined: Oct 2002
Posts: 5,246
Likes: 3
From: Ivoryton, CT
Default

Originally Posted by prosno
okay I checked a few things today, engine is 454 330 hp, outdrive is geared 1.47 and is a rebuilt lower unit. Going to mess with it this week end I hope and write down all results. Thanks a bunch guys, Dave I hope to see ya on the river, gotta post some pics of this thing soon.
19p M+

See you on the River...
__________________
Patrick
Pat McPherson is offline  
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
brian valery
Prop Talk
2
06-08-2007 08:44 PM
kilroy
Prop Talk
5
05-17-2007 03:09 PM
kilroy
General Boating Discussion
4
04-07-2005 05:30 PM
Steamin Rice
General Q & A
2
09-28-2004 05:15 PM
Whitey
General Q & A
0
08-06-2002 11:35 PM

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.