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Standoff-Extension Boxes, Pros and Cons

Here we go the boat started out as a 575sci with xr's did mods to motor made 742 hp changed to scx-4 done a bunch of testing spinning in out,different rake props,pitch etc. Boat ran the fastest spinning in but bow steere, had to add a 1 in spacer got handling back and lost mph ran like that all season around 65 hrs had torrent (jason) hang off the back of boat when running and the water around the drives and props is full of air if I put boxes on get drives in cleaner water should be able to dial in slip easier.When you get over 700 hp slip is a big factor that people forget about.I got my rpm I can dial in with pitch but now time for slip witch if I can get that dialed in the boat should all around be better.We have tried everything with the props and slip is still high.I'm not going to get into all the tech on props but jeff at hering and brett at bblades are doing all the prop work together.Got thousands into shipping and trying different props.
 
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It seems to me your are on the right track with boxes. IMCO makes good stuff. Since you have found the height threshold on the boat you are half way there. It is great you have all the adjust-ability the IMCO drive has to offer. I agree back and up as you said 12 plus 1. The change in attitude will probably allow you to go up second inch[ the one you spaced down for] and not bow steer. No telling until you try it it might even tolerate 1/2 or 1 more to boot.

I suspect that change will make the boat feel more nimble and more fun to run. As big as the boat is the extend reach of the props back will prove helpful in the rougher stuff too.

Perfect time to get started and be ready for next season.
 
Ryan, how much did it slow down when you added the spacer? From what to what?

And have you checked the bottom really close for any imperfections yet? Jim can explain the differences in small hoks and imperfections better than I can. And how they make bigger differences at the faster speeds.....
 
Spacers only slowed down 2 to 3 mph.And the bottom is pretty close not blueprinted but close.I've done some much testing and it's consistent if the bottom was really off the testing wouldn't be consistent.
 
So you've checked all the little stuff? No hooks, rocker, pits, bumps etc? Sometime when you're in this area give me a shout. You would not believe some of the stuff on the bottom of mine.....
 
Of course, now you've made another question come to mind. When you blueprint a bottom, because of a step boat do you also have to blueprint the area of the two steps to each other?
 
The important thing is to make sure there are no low spots in any of the main running surfaces. A low spot or hook causes a vacuum and has a huge effect on speed. The effects increase the faster you go. Sharp tailing edges and stakes are less important at 80 then at 100 and up. A significant low spot in a critical area can create a level drag that is so great at speed that it will make any change in props , heights or set up seem irrelevant.
 
It changes based on what the boat is running speed wise. I am not aware of any chart or hard fast rule but, in general based on what I have witnessed say more than 1/4 on a 70 mph, 1/8 at 80, A 1/16 at 90, and any light seen under a straight edge at a 100 or more on the running surface or surfaces. The size of the low spot will factor in as well.
 
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What do you use to fill these low spots?

I hung my old Glastron from My garage ceiling years ago and blueprinted the bottom. I made everything smooth and straight.
That boat worked when I got done with it. Wish I still had it today. I would put adifferent drive on it so that it wouldn't blow every other weekend. Over 500 HP SBF.
 
Do you recall the comparison of before and after? And how much work/changes you had to do?
 
It was sitting on a roller trailer for the first 7 years I owned it and at every roller the bottom was indented. Converted the trailer to a bunk and smoothed the bottom and regelled it. Way too many years ago to remember how much work it was, I had a bad habit of making MAJOR changes so I couldn't tell you what improvement that created. It helped with handling - that and raising the drive so the shaft was 3 inches below the pad. That boat flat out flew when I got done with it. It was one ill handling boat with HP added when it was stock. Stock it did 50 MPH with 188 HP. best I saw was 94 GPS before I sold it.
 
Thinking on buying two IMCO neutral boxes, hyd rams and hardware, inner transom mounts. Basicly everything to add boxes and hyd steering to my boat except the helm and hoses. $6400 plus shipping --- what do you think??
 
New boxes with everything but the steering rams are around $5700 thats the hd shafts boxes inner plates hardware and wing plates.That was a quote I got for 2 of everything.
 
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It was 2850 each when buying two that was my quote not sure if I got a deal have spent alot of money with imco in the last year. So 5700 total for two setups.
 
That seems like a decent price to me. If course that doesn't invclude the power steering pieces like he was asking about above. They both seem like decent deals to me.
 
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