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lesson on twin stepp take off

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Old 03-27-2009, 12:42 PM
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Originally Posted by BraceYourself View Post
Big question is............

How does it run once on plane.

1.) Does it accelerate well
2.) Does it turn max rpm without excessive trim
3.) How is the attitude of the boat


If you answer yes, yes, and feels stable... Then... this aint your moms minivan, it takes a little finess. Your fine just learn its characteristice.
The guys with cats have it way worse.
yes once on plane it runs great!
you might be right,I may need to get to know the boat
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Old 03-27-2009, 12:44 PM
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Have BBlades add some cupping to the props.
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Old 03-27-2009, 12:52 PM
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You might check your drive spacing as well. If you're running short, it's going to be more prone to blowout at the start, but you gain more top speed. If you're running long, your prop sounds like it might be too small of a diameter, or the rake needs to be cupped a little more.

Small 1/2 inch changes here & there can make a huge difference when dialing in a boat. Good luck.
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Old 03-27-2009, 01:39 PM
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I'm running 28 Bravo's turning out on my 292 twin stepped Formula. It has twin 6.2's and the props are labbed finished. When getting on plane the props 'slip', but not to the point where the boat stops accelerating. If I push the sticks all the way when getting on plane both engines will peak around 3600-3800 rpm and she will nose over just fine. As it noses over I am trimming the outdrives out and the props really start to hook-up then.

It kind of reminds me of having a high stall speed torque converter like in my old drag car. Prop slip getting on plane is easier on the outdrive gears. You may want to try and spin them out(?)..
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Old 03-27-2009, 01:45 PM
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Would highly diagree on prop slip being easier on drives. They slip and catch putting higher torque loads on the gears. Also full throttle to get on plane in most boats would break the drive after a half dozen times.
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Old 03-27-2009, 02:37 PM
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Quote:
Originally Posted by Griff View Post
Have BBlades add some cupping to the props.
I agree talk to Brett at BBlades. All the high performance boats I have owned V and cat, I/O or outboard, had to be persuaded out of the hole. And yes the cats have been the worse. That's the price you pay for best MPH, but like they said it has to handle too. There has always been a compromise in my boats performance and setup. You just get use to dealing with it.
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Old 03-27-2009, 03:11 PM
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Quote:
Originally Posted by BraceYourself View Post
Would highly diagree on prop slip being easier on drives. They slip and catch putting higher torque loads on the gears. Also full throttle to get on plane in most boats would break the drive after a half dozen times.
Hmmm... I guess that may be true, but I have heard comments about 5-blades being harder on drives and they slip less(?) ... and my 4-blades don't really slip and catch, it is fairly smooth and they slowly grab after it noses over.

I agree completely what you are saying regarding full throttle starts. I have done it very few times and those little small blocks don't have the torque of a big block. What I was trying to point out is that the props never go into full cavitation mode where you have to take it off plane, but they are still pushing, even at full throttle.

Last edited by 4mulafastech; 03-27-2009 at 03:14 PM.
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Old 03-27-2009, 03:24 PM
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bigger diamerter props, spacers, or boxes. I'm not a fan of adding cup. A little is ok, but too much will effect handling.
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Old 03-27-2009, 03:27 PM
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you can't mash the throttles, props will slip. needless to say it's bad for the motors as well. Symptoms will vary, the heavier you are (people, fuel, gear, etc) the more noticable it will be. The lighter you are the less noticable it will be. With my twin step I just have to ease it onto plane, ease it past 2500, then you can give it more and more throttle to bring the bow back down.

It's more or less a feel thing, the more seat time you get the more controlled you'll become. I'm itching to get back behind the wheel of mine. Sooner or later you won't even have to think about it and the motions will just come naturally.
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Old 03-27-2009, 05:44 PM
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this happens alot to first timers with step boats. take some classes and i am sure you will be fine.
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