Notices

Scarab 29 Top Speed

Old 04-23-2017, 09:37 AM
  #1  
Registered
Thread Starter
 
Join Date: Apr 2013
Location: Tampa, FL
Posts: 93
Likes: 0
Received 1 Like on 1 Post
Default Scarab 29 Top Speed

1997 Scarab 29, Twin 383 Mercuiser Mags (350HP each, stock), Bravo 1's with 23P Mirage props spinning out. I am only getting 65-66 mph @ 4,900 RPM's with drives out, tabs up. Shouldn't this boat be going faster? This model supposedly does 67-68 mph with stock 350 MPIs which I believe were rated at only 300HP vs the 350HP of my engines. Suggestions on getting more speed? Different props? I feel this set-up should be going 72-73 mph.
CLASSIC MUSCLE is offline  
Old 04-23-2017, 03:21 PM
  #2  
Registered
iTrader: (1)
 
scarabman's Avatar
 
Join Date: Nov 2002
Location: TR, NJ
Posts: 2,005
Received 194 Likes on 101 Posts
Default

Bought the one out of NJ? Are the props Mirage, or Mirage Plus? Gear ratio in drives is 1.5? Yes, you should be able to run a bit above 70 with your power.
scarabman is offline  
Old 04-23-2017, 03:39 PM
  #3  
Registered
iTrader: (1)
 
Join Date: Nov 2009
Location: KY
Posts: 4,082
Received 459 Likes on 357 Posts
Default

If you have 1.5 drives your slip is at 7.2%
Getting your rpms up to 5200 with same slip you would be hitting 70 mph
Reduce slip to 5% gets you to just under 72 mph

Are the motors tired, have a lot of hours?
AllDodge is offline  
Old 04-23-2017, 05:59 PM
  #4  
scarab
Gold Member
 
trc2's Avatar
 
Join Date: Aug 2006
Location: Easton Maryland
Posts: 315
Likes: 0
Received 0 Likes on 0 Posts
Default

make sure your trim tabs are going all the way up the 29 scarab i had had a spacer in the cylinder and would not let the tabs come all the way up put a straight edge on bottom of the boat to the tab and check that way and i can tell you a 2 or 3 inch shorty will really wake that boat up as far as ride and speed
trc2 is offline  
Old 04-23-2017, 06:20 PM
  #5  
Registered
Thread Starter
 
Join Date: Apr 2013
Location: Tampa, FL
Posts: 93
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by scarabman
Bought the one out of NJ? Are the props Mirage, or Mirage Plus? Gear ratio in drives is 1.5? Yes, you should be able to run a bit above 70 with your power.
Yes, I got the boat from NJ I was looking at. It's on Lake Norman now, in North Carolina, and will also be seeing time in Tampa, FL. I think the props are Mirage Plus but I'm not by the boat right now to 100% confirm. Drive gear ratio's I'm not sure. How do I check that?
CLASSIC MUSCLE is offline  
Old 04-23-2017, 06:21 PM
  #6  
Registered
Thread Starter
 
Join Date: Apr 2013
Location: Tampa, FL
Posts: 93
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by AllDodge
If you have 1.5 drives your slip is at 7.2%
Getting your rpms up to 5200 with same slip you would be hitting 70 mph
Reduce slip to 5% gets you to just under 72 mph

Are the motors tired, have a lot of hours?
The motors should be good. They are 2012's and have about 180 hours. All cylinders were strong when tested during the survey.

Last edited by CLASSIC MUSCLE; 04-23-2017 at 06:49 PM.
CLASSIC MUSCLE is offline  
Old 04-23-2017, 07:42 PM
  #7  
Registered
 
Join Date: Feb 2012
Location: westville, NJ
Posts: 4,031
Likes: 0
Received 9 Likes on 7 Posts
Default

Rev limiter?
dereknkathy is offline  
Old 04-23-2017, 08:00 PM
  #8  
Registered
Thread Starter
 
Join Date: Apr 2013
Location: Tampa, FL
Posts: 93
Likes: 0
Received 1 Like on 1 Post
Default

Mercury rates the 383 Mag at 4,800-5,200 RPMS. I think I'm turning about 4,900.
CLASSIC MUSCLE is offline  
Old 04-23-2017, 08:01 PM
  #9  
Registered
iTrader: (1)
 
Join Date: Nov 2009
Location: KY
Posts: 4,082
Received 459 Likes on 357 Posts
Default

BTW are you reading the speed with a GPS?
AllDodge is offline  
Old 04-23-2017, 08:09 PM
  #10  
Registered
Thread Starter
 
Join Date: Apr 2013
Location: Tampa, FL
Posts: 93
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by AllDodge
BTW are you reading the speed with a GPS?
Yes, the boat has a Raymarine system installed and it has GPS. I probably should double-check it with phone though too.
CLASSIC MUSCLE 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.