Aero Tek With Cavitation/blowout Problem

[BIG SLICK]

hi,i purchased a 28 aero tek with a single engine beck racing 509,last fall and am experiencing a problem,after the nose of the boat comes down on plane,the prop is throwing alot of water around takes forever sometimes before the prop finally hooks.once it does its fine until the next time i stop or slow down.ive tried 3 props a 3 blade mirage was on it when i bought it,a new 4 blade power tech and a 4 blade labbed bravo 1.the problem exist with all 3,with a 1/2 inch spacer in the outdrive the center of the prop shaft is 6 inches below the keel .the keel stops about 8 inches from the transom and there is a flat pad about 24 inches wide and 4 inches higher than the keel..i dont know if this has anything to do with the problem?there used to be something mounted on the pad,there are 6 holes that were filled in at one time on the flat area.some people are telling me to put more spacer in it,some telling me to try a 5 blade prop.any ideas would be helpful.thx tim

[AIR TIME]

6'' is starting to get deep I would try a 5 blade px that will give you bow lift the p 5blade is a stern lifting so you don't want that call BBLADDES ask for brett. ps my baja had a 7'' depth and thats deep. I have 5''now that is starting to get high. art

[DMOORE]

So, is the centerline of thew prop only 2 inches below the transom? Also does your boat have trim tabs? Tabs will definatly help you get on step. It's not uncommon for a performance boat with a high drive and big prop, to ventilate the prop when comming on plane.


Darrell.

[BIG SLICK]

hi guys,the prop is 6 inches below the point on the keel or 10 inches below the pad.i do have trim tabs but they are the small type that are made by bennet.prop is approx 14 3/4 its been labbed.???

[Wild Card 09]

My friend Marcus, here in Germany has the same boat. It ran great since he bought it new, in 1996. Then he wanted more power.
Out came the 502 and in went a 900 HP Taylor performance 540. At the same time, he fitted an Imco extension box and sc drive. In order to make some space for the new instalation, he removed the strange pipe that goes down to the notch,under the transom, and sealed everything up.

Then he tested his new rig.
The boat did exactly what you described. When coming out of the hole and up to 50 mph it was sending water everywhere, and didn´t want to go much faster, even when he let all 900 ponies loose.
It felt like it was somehow sucking itself down, and only when he would violantly rock the wheel back and forth, would it suddenly break free and shoot away up to 90 mph!

It turns out the Aerotek hull needs this vent pipe (it runs from the back of the notch up to the top of the transom under the rub strip) and was put there by the factory for a reason.
It supplies the notch with air and stops water being suck up into the notch as the boat accelerates.
Sound to me like someone has removed the one on your boat.
If you want details on where it should be, let me know.
The Aerotek is an amazing boat, and handles the big motor really well.
By the way, don´t go down with your drive, the hull likes a high x.
Marcus, Imco shorty, and has raised the whole box and motor as well. He is running about 2 1/2" propshaft to hull bottom dimension, and the boat runs great.

[BIG SLICK]

man im glad u saw my post!the boat looks just like mine.i have no idea what this vent pipe is or looks like.anything u have would be great!thanks tim my email is ready2race@cox.net

[Liquid Fix]

I have a 1994 28' Aero-tek and it does the same thing and has had the problem ever since I've owned the boat. Mine has never had the vent tube down to the notched transom. What I have found on mine is after the boat comes on plane I take the boat into a slight left hand turn and the prop instantly hooks up. Works everytime but it does suck when your coming on plane in traffic like at the start of a poker run.
Wild card 09: Is there a chance you can post a pic of the vent tube on the transom of you buddies boat?
Oh yea, mines going on the market in the next few weeks if you know anybody looking for one......
Thanks, LF

[BIG SLICK]

hi lf,does your transom look like mine?your boat is the same as my 94 exept for the colors and the air vents on the side.looks good!what kind of hp do you have?

[Wild Card 09]

The notch looks like on Marcus´s boat. I´m meeting up with him tomorrow, and will tell him to check out this thread. I´m sure he´s got some good pictures showing how things should be. We are out on a run at the weekend so it will be monday before he posts anything.
It seemed incredible to us that this pipe could make such a difference.
When he was running it without the air pipe, there would be this strange rumbling noise acompanying the water spraying up from the drive. Like i said he found that if he rocked the wheel, or hit a large wake, the boat would suddenly break free and run like it was supposed to.

After the pipe was back in, his boat was a rocket ship!

He still hasn´t found its top speed, but it is waayyy past 90 for sure.

[BIG SLICK]

that sounds great!it would be much appreciated.