Re: Extension Boxes and Set Backs
 

Krak,
Do you know how far below the bottom your prop shaft is?

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... :cool:

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

However, from what jcap has told us, the slip numbers really start to rise as you push a Y2K toward 90mph... :rolleyes:
Professor jcap learned that a 2" spacer and a 5 blade prop gave his boat the added bow lift to crack 90mph. :D
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... :cool:
Mount the engine and drive in the proven location. Add the neutral extension box and that Big Azz 572 and see how she runs! :D :D :D

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.

Re: Extension Boxes and Set Backs
 

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

Rick

Re: Extension Boxes and Set Backs
 

In the water on the fly sounds cool!

Re: Extension Boxes and Set Backs
 

To see more do a OSO search for 'on-board-dyno pictures'.

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?

Re: Extension Boxes and Set Backs
 

Alright now I'm confused as HELL! :eek:

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

Re: Extension Boxes and Set Backs
 

6...
But there is still about a foot of snow on top of my boat...:rolleyes:

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

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

Tom,
The only other OSO member to talk about an extension box on his 30 is Zuperboat.