lesson on twin stepp take off
 

how do you guys accelatate from a no wake with out breaking props loose,I must be doing something wrong because as soon as I hit 2500 to 3000 rpm,props breaks loose,
had props checked out by airmarine and was told they are perfect,30 foot twin step boat with 496 mags,1.5 bravos spinning in 28 bravo 1s

I was also told by others,welcome to the world of step bottom boats,that cant be right or is it?

1st time step bottom boat owner,all other boats have been V bottom boats.

thanks for any input

I just don't see it breaking the 28 p props loose whith stock 496 s

My 42 tiger would always break loose. I just knew right when it would and would pull back briefly then they would catch again and all was good. Would also start bringing the tabs up to help get on plane. Once I figured it out it was a piece of cake.

What the man said.

I assume this boat is new to you could be the previous owner swapped props before they sold it also.

Did you take a test ride before purchase? If not try contacting the previous owner for tips or try a set of 5 blades.

Trim the drives all the way in (also check the trim on the trailer) tabs down, and SLOWLY increase throttle, back off slightly when they start to break loose and ease into the throttles again.

Hope this helps.

You just need to pull back on the sticks when it starts to blow out and start trimming the boat out. My fountain would do the same thing....just didnt like to go slow :drink:

I wish you right,BUT it breaks them loose big time.

thanks for the input

The boat was a repo so I cant get a hold on anyone,
did find some specs on the boat and the 496ho came with 30 bravos and the 496 mags came with 28 bravo which is what I got.

thanks for the input.

All fat gals report to the front of the boat.

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

Have BBlades add some cupping to the props.

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.:ernaehrung004:

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(?)..

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.

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.

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.

bigger diamerter props, spacers, or boxes. I'm not a fan of adding cup. A little is ok, but too much will effect handling.

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.

My boat doesnt do that!!! Where are you setting the tabs? Do you know you have tabs? :rolleyes:

When I get better you show me!

Sounds like some cup might help.

this happens alot to first timers with step boats. take some classes and i am sure you will be fine. :evilb:

thanks for the reply:confused::confused:

Drives in; tabs down; ease into the throttle 500 rpms at a time until it starts to slip, pull back a bit until it bites, then increase throttle slowly while trmming the drives out; tabs up -drives out; tabs up...take your time.

Once you get the feel it will become second nature. It is not a drag boat and is a prefectly normal occurence.

Definately use the tabs Tom. It will make all the difference.

glad i found this thread. I just bought a 388 slingshot and went up to test the boat with Joe and john from hustler. I noticed that when the boat came up on plane. The props sliped and jo would back out and then get back on the sticks and adjust drives and tabs. Jo then explained about how to plane the boat out. I've only run V bottom so this is new to me i thought i needed different props now i feel better that it just something i have to learn:cool:

This may sound like a stubd queston but its not. first what is the make of the boat? Does the boat have a pad as well as steps? If your boat does have a pad do you have blow out vents under the pad with shut off valves in the engine compartment? Most step bottom boats that don't get on plane quick need to get the air that is trapped under the pad out. Donzi 35ZRs have blow out vents and I believe Fountain does the same. When you take off try neutral positon on your tabs that would be around 3-4 depending on your boat, make sure your drives are tucked all the way in and ease your throttles foward, If you feel the slip back off very slight on your throttles until you feel the grab and then push foward. Bravo 1 props are your best choice with 496s, Going 5 or 6 blade will not help with the slip and will destroy your X drive, 496s don't run XR drives. I have 496s in my 33 ZX I added blow off vents in my boat and have no problem getting on plane. The previous owner put bigger K-Planes on the boat and that did not help it actually made the boat worst on take off! If you bury the tabs all the way down on take off, you will actually lift the stern of the boat adding more air to the underneath.

Hi Frank !!!!

Hey Gary

this is basically how I do it..it differs from time to time..usually one side will break loose first then I push the other throttle slightly forward to compensate and when both equall and on plane start to bring the tabs up..Boat goes up pretty quick for the beast that she is..

this may be just another stubd queston and may not mean much hear with theas boats but has any dealer R&R the drives lately ? at the rear trim ram pin with the black caps covering the nut's there is a white plastic spacer in between the nut hard wear that could be installed wrong and it will change the drive trim angel a bit not leting the drive tuck in as far.they do this becouse there is a differents between bravo 1 & 3.and some guys will change that around by not knowing where to put it.on bravo 1 the spacers need to be installed with the grove part pointing a way from the bow of the boat or a way from the boat in general. well i'm shur it's fine but if not it a easy thing to look at any ways.it dose sound like the x is high but that is where the top speeds come in.you would think the manufacturer,s would by now say to you oweners to install lower unit drive spacers by now to help stop the blow out. merc dose sell them spacers also.just an idea is all this is.good luck and have fun this year boating.

sorry for the stupid question, but what are blow off vents?

This is a good point and may be worth looking into. I completely forgot I changed mine a couple years ago. The spacers were positioned from the factory to prevent the drives from tucking under as far as possible. The reason is if the drives are tucked 'too' far at speed in a hard turn, it is more likely to spin-out/roll a twin stepped hull due to the added stern lift. I never have my drives tucked all the way in when turning (rule #1 of driving a stepped hull). I changed the spacers to allow the drives to tuck in further and it helped with planing. Although, the props do still slip which is the nature of a stepped hull and a higher x-dimension.

just stick 1000# of sand in the bow.. that should fix it:party-smiley-004:

On

On a step bottom boat on the rear pad there would be two 1/2 or 3/4 brass thru hull openings that runs through your engine compartment out the transom or sides, They will have shut valves so if they leak you can shut them down. What happens on take off excess air gets trapped in the padded area and causes excessive prop slip and blow out. The Blow offs get the air thats trapped out from under the boat and reduce the slip from start.
you will see on the back of a lot of number 6 Drives these 2" black tubes coming off the back of the drive and they come up over the drive, this does the same it release the excess air from a step bottom boat and reduces prop slip. Helps the boat get on plane faster.
Thats why I asked what kind of boat and does she have a pad on the rear of the boat.

actually if you read the thread,I need to add the sand in the back so I could keep the stern in the water.

thanks for the reply

thanks for taking the time to explain how blow off valves work!

the boat is a 2003 powerquest revenge with a small pad

I've had that exact thing happen after having a drive worked on with the Gun. It definitely can be overlooked, and made my boat cavitate like hell until it was swtched back. :ernaehrung004:

Well I just checked the trim limit blocks and they were on backwards,once I switched them the outdrives lowered about an inch,hopefully that will do it,I will let you guys know the results next time I go out.

Thanks for all the replys!

A friend had a 34' PQ that also has the 2 large steps. His drives had spacers on it when he bought it. Possibly for this very reason?