Blowing out while taking off.
 

While trying a new set up on boat we are blowing out pretty bad as we go to get on plane. We are running a new set of merc racing 30p heavy labbed props spinning in and the drive showers are mounted on the outside edge of the the drive. The boat is a PQ 30 Revenge with twins 425hp's and bravo drives.

Does anyone have any suggestions or thoughts?

Thanks.

Any pictures of the setup, showing drive height and setback?

IMO, if you only have twin 420s for power, you are way over propped. I might be wrong, but I would think you would need a few more horses to turn 30" wheels, labbed or not. My first boat was a 30' and it was overpropped. It blew out everytime I came on plane.

Just my .02

BTW, what prop was on the boat before you switched?

I agree with the above, that does sound like a lot of prop for the power. What gear ratio are you running?

Also, if you're using cleavers for the first time, they dont hop up on plane like a typical set of B1's will. You typically have to give them some RPM to get them to hook up.

Short boat with high drives will blow out every time. Tabs down, ease up to 3500 rpm and let it do it's thing.

It had a set of 30's on it when I got it but they were not as labbed. Original set up was 28's but at 375 hp per side, they were upgraded to factory 425hp 496's by previous owner. I was wondering if 28's might not be the way to go.

Does anyone think the drive showers could be adding to problem?

Well, I'm running 28s on my 32 Advantage Victory w twin 375 496s, and at times, I think they may be under pitched. I bought the boat with 26s and the rpms were way too high, around 5000. The 28s brought the rpms down a bit, but it still runs too high at 5800. This boat rockets out of the hole too. Never any blow out and very little slip. I would think 425s should turn 30s no problem.

I think you better stick with the original bravo 30s,boat ran great with them .my 2cents

outdrive showers are on the up rotation of prop,just as they should be.

It's pretty easy to find out if the showers are affecting planing. Take them off.

Also, there is a technique used on some of the highly tweaked boats and/or race boats that involves pushing the boat as far as you can get it up before it blows out; and then pulling back on the sticks. This will give you a large wall of water hitting the back of the boat that you can use to surf you up, as well as power through with the sticks.

Sometimes, you can rock a boat side to side and get it to come up as well, but I really hate turning the wheel more than a few degrees if you have the tabs down significantly.

What kind of rpm were you turning the old & new props?

How does the max rpm range of the old & new power compare?

If the upgraded engines turn 200-300 more rpm you might be better off running the orig size prop-28.. just a thought..

Rick