Go Back  Offshoreonly.com > Owners Forum > Superboat
Extension Boxes and Set Backs >

Extension Boxes and Set Backs

Notices

Extension Boxes and Set Backs

Old 03-13-2005, 01:51 PM
  #31  
Registered
 
FASTERDAMITT's Avatar
 
Join Date: Jun 2002
Posts: 2,001
Received 2 Likes on 2 Posts
Default Re: Extension Boxes and Set Backs

Krak,
Do you know how far below the bottom your prop shaft is?
FASTERDAMITT is offline  
Old 03-13-2005, 06:20 PM
  #32  
VIP Member
VIP Member
Thread Starter
 
Pat McPherson's Avatar
 
Join Date: Oct 2002
Location: Ivoryton, CT
Posts: 5,246
Likes: 0
Received 3 Likes on 3 Posts
Default Re: Extension Boxes and Set Backs

Looking at the numbers posted by Krakmeup and fastedy, the stock set-up would seem to be right on...

Krak's boat: about 72mph @ 5000 with a 26p...
Fastedy's boat : about 82mph @ 5000 with a 30p...
I don't think you could ask more from a V bottom...

However, from what jcap has told us, the slip numbers really start to rise as you push a Y2K toward 90mph...
Professor jcap learned that a 2" spacer and a 5 blade prop gave his boat the added bow lift to crack 90mph.
I believe jcap gained 4-5mph from 87 to 91+...

Now how does this all relate to an extension box?
What is the norm; raise the prop 1" or 2" with the 12" extension?

Tom, I like your latest thoughts...
Mount the engine and drive in the proven location. Add the neutral extension box and that Big Azz 572 and see how she runs!
__________________
Patrick
Pat McPherson is offline  
Old 03-13-2005, 07:35 PM
  #33  
Registered
 
Join Date: Jan 2001
Location: PA and MD
Posts: 1,461
Received 2 Likes on 1 Post
Default Re: Extension Boxes and Set Backs

Run the Stelling box and then put in my Dyno in it and see just how much power your boat is putting out and you can 'dyno your hull' that is see how much HP/TQ it takes to go a specific MPH.
cobra marty is offline  
Old 03-13-2005, 08:08 PM
  #34  
Registered
 
FX10's Avatar
 
Join Date: Apr 2004
Location: Emerald Isle, North Carolina
Posts: 4,509
Received 3 Likes on 2 Posts
Default Re: Extension Boxes and Set Backs

Marty,
That sounds like a cool package you have there.

Rick
FX10 is offline  
Old 03-13-2005, 09:10 PM
  #35  
Registered
 
FASTERDAMITT's Avatar
 
Join Date: Jun 2002
Posts: 2,001
Received 2 Likes on 2 Posts
Default Re: Extension Boxes and Set Backs

In the water on the fly sounds cool!
FASTERDAMITT is offline  
Old 03-14-2005, 02:32 AM
  #36  
Registered
 
Join Date: Jan 2001
Location: PA and MD
Posts: 1,461
Received 2 Likes on 1 Post
Default Re: Extension Boxes and Set Backs

To see more do a OSO search for 'on-board-dyno pictures'.
cobra marty is offline  
Old 03-14-2005, 12:25 PM
  #37  
Registered
 
jcap's Avatar
 
Join Date: Sep 2002
Location: babylon ny
Posts: 364
Likes: 0
Received 0 Likes on 0 Posts
Default Re: Extension Boxes and Set Backs

my y2k did not like the ext box, and boxes often do NOT increase bow lift ,they make the boat longer thus increasing the length of the leaver and push the fulcrum farther back, in fact they increase stern lift, my boat lost bow lift and about 2 mph with a neutral box ,
jim

how many days till spring?
jcap is offline  
Old 03-14-2005, 12:59 PM
  #38  
Registered
 
FASTERDAMITT's Avatar
 
Join Date: Jun 2002
Posts: 2,001
Received 2 Likes on 2 Posts
Default Re: Extension Boxes and Set Backs

Alright now I'm confused as HELL!
FASTERDAMITT is offline  
Old 03-14-2005, 01:11 PM
  #39  
Registered
 
FASTERDAMITT's Avatar
 
Join Date: Jun 2002
Posts: 2,001
Received 2 Likes on 2 Posts
Default Re: Extension Boxes and Set Backs

Let's post some results to clarify some of this. Who can list all the 30's that have boxes and results?

The boat 30' Y2k Tempest
OSO name
Hp
setback
rise or std box
prop
speed before
speed after

Last edited by FASTERDAMITT; 03-14-2005 at 01:13 PM.
FASTERDAMITT is offline  
Old 03-14-2005, 02:13 PM
  #40  
VIP Member
VIP Member
Thread Starter
 
Pat McPherson's Avatar
 
Join Date: Oct 2002
Location: Ivoryton, CT
Posts: 5,246
Likes: 0
Received 3 Likes on 3 Posts
Default Re: Extension Boxes and Set Backs

Originally Posted by jcap
how many days till spring?
6...
But there is still about a foot of snow on top of my boat...

Good to here from you Jim!
I hope all is well!

Sounds like jcap just may have saved you fellows a bunch of money...

Tom,
The only other OSO member to talk about an extension box on his 30 is Zuperboat.
__________________
Patrick
Pat McPherson is offline  

Quick Reply: Extension Boxes and Set Backs


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.