J 3.0L FingerPort. Prop slippage

[ggodwin]

Folks teach me a little about prop slippage. Input the 409T with the J 3.0L 225 in the water today. Seemed sluggish on the hole shot. It also seems to have some prop slippage. It felt like a bad clutch on a car. My trim gauge wasn't working so that bothered me a little. I was on a small lake and never could open it up much. The boat was at 53mph at 5000 rpms.

On some of the hole shots as the boat was accelerating I would get a vibration and the rpms seemed to jump.

The prop is a Raker 14.5x28

 

[flyingscott]

Is this boat new to you?

 

[ggodwin]

First time ever in it.

 

[flyingscott]

You should be around 5500 rpm with that motor. It sounds like the motor is over-propped. Does the prop have vent holes in it?

 

[ggodwin]

Not sure on the vent holes. I'll pull the prop off here soon.

Just confirmed my Pad to Prop level. This is a 95' Javelin 409T with a slight V on the bottom. I took my pad measurement from the lowest point on the pad. Which is the crest of the V in the center of the hull. It measured 16 Inches. With my motor trimmed parralel to the ground it measures 12.25" for a 3.75" pad to prop measurement. However, I am not sure if I should have measureed from the tip of the V. Because it is a slight V I don't think the pad is at the crest of the V.

 

[Faztbullet]

I have a 1999 409DC with similar motor...what you see is all normal as the Raker vents as it breaks over and the vibration is the blades slapping water till they bite. Should be a 68-72mph ride if you can turn the RPM.

 

[ggodwin]

Fazt,
What prop are you running to get those speeds? I don't need to set to water on fire. But, i do want to know the motor is working efficiently. It doesn't seem like it is. Do you think 3.75" below pad is too deep?

 

[Faztbullet]

What is 3.75 below pad???? If you run a straight edge/level off bottom of pad with engine trimmed level it should split the middle of the 4 water pick up holes. I run a modded Raker 28 @ 5900

 

[ggodwin]

What is 3.75 below pad???? If you run a straight edge/level off bottom of pad with engine trimmed level it should split the middle of the 4 water pick up holes. I run a modded Raker 28 @ 5900

The center of the prop axle is 3.75" below the pad of the boat. Since this post I have raised that point. Approximately 3.5" now. I didn't compare to the water pick up. But, I did take the boat out and that did help some. At WOT I'm getting about 40 psi on the water pressure gauge.

 

[ggodwin]

I just measured the water inlet holes. The center of the inlet holes is exactly 1 inch below pad.

 

[ggodwin]

I was targeting 3.5 Inches below pad based off of these instructions.

 

[ggodwin]

I just measured the water inlet holes. The center of the inlet holes is exactly 1 inch below pad.

I mis spoke here. My inlet holes are exactly 1 inch above pad level.

 

[Faztbullet]

Since you said you raised it I assume its on a jack plate. How much set back is it???

 

[ggodwin]

Correct. It it setback 10" behind the transom.

 

[Faztbullet]

Raise jack plate 1 "