STV Help

[tommyJ]

Have a 1999 STV River Rocket.

Have had a 6" jack plate on the boat and now we have the motor bolted to the boat. We are running the prop shaft center line anywhere from 1/2"-1" above the pad. Propellor is a 14x24 yamaha. Just after 9000 rpm, this boat is violently hooking to the right. What are we doing wrong?

Ran Allisons for 10 years and never had a problem!

Any thoughts? Please help!

[ProComp]

I talked to Dave about this. Very strange.
What type of steering is in the boat?
Have you tested with a different gearcase and or prop with the same results?

Welcome to Scream & Fly

[STV_Keith]

Sounds like a blowout. What type of gearcase and is the blowout ring still in tact? Post a picture.

[WATERWINGS]

Welcome to Scream and Fly......does the gear case have a torque tab?

Can you look back at the motor when you are going straight at 60-70+ ?....Is the motor crooked, or straight?

[Hole$hot]

Wow. Your still having this problem after changing it? Crazy. I would try a different case.

[Hoss Marine Propellers]

Welcome to S&F !!!!
It sounds like blowout to me also?
Motor may be a little high for the 14" dia. prop.
Can you drop the motor fairly easy without the jackplate on it?
Just to try something different? See if the prop holds at a lower setting?
Also, the comments about torque & crabbing the gearcase would have the same effect at that height
with the 14" dia. props...... loosing bite!

We always ran 14 1/2" diameters that high on the STV's & Mirages.

[tommyJ]

More info:

This boat was owned by a friend of ours. Even though it's a 1999, it had 23 hours on it, it's still new. The steering is the original dual cable and the gear case is a brand new Mercury sport master. On tuesday, we re-installed the hydro dynamics 6" jack plate and adjusted the height so that the center line of the prop shaft was even with the pad which is similar to our old v-bottom set ups. The boat finally worked! With the 14" prop, this seems to be a sweet spot. The boat felt safe and very controllable. I'm 61 years old, I don't need any more right hand turns! I would like to thank everyone who gave us input on this problem.
Thanks again!
Gordy Johnson

[samari]

Good to hear it's working. Will we see you guys in Albert Lee? I sure hope so, it was cool to race with Tom in Menominee.

[hydrostream1]

I have a 09 stv river rocket,with CLE lower unit,long skeg on it,most cle's have a straight down skeg,that won't work.Needs to be like the Allisons .I would contact Jack Barsh,full throttle powerboats,he builds these boats and quarter shots.I haven't seen these with sport masters at the races I go to,most use.the small xr6 nose coned gear cases,but the CLE gear case with modified skeg works good too,have had mine 110 mph with no problems,but that is also in a straight line drag racing.