wrong prop, setup, or both

[baldben]

I bought my first bass boat 3 yrs. ago and have been using and fixing things ever since. It is a 1997 Javelin 400 TE with a 1997 Johnson 200 venom. At WOT I am at about 5400 rpms and 57-60mph. I am not a speed hound so that is ok, but a little more wouldn't be bad either. My real problem that I am hoping someone can help me with it getting on plane. I enjoy fishing a couple of local tournaments and off the start my boat does not perform well. If I drop the hammer it sounds as though it is free spinning and the engine races, I believe this is called cavitation. If I go 1/4 to 1/2 throttle I can get it on plane and all is well. I want to fix this so I don't always have to be thinking about it on the start, also the other day with full live wells I had to take 3 tries to get it on plane time I don't need to be wasting.
The prop shaft is 6 inches below the keel when at half trim which seems a little low to me,but if I raise it I assume it would only make the problem worse. The prop is a 4 blade stainless steel shooter 13 1/4 X 27, I don't have a jack plate but can raise it on the transom with an engine lift about 2 inches. Any help would be appreciated and unfortunately I live in an area with only one boat shop and they will only work on Mercury so I will have to try and do most of the work myself. I don't believe anyone in my areas will let me try props either so this may be tough to fix since I can't spend the money on 2 or 3 props to try out. Thanks to anyone who can help.

 

[steelespike]

Just off the top of my head I think your diameter is too small. While a 4 blade will usually have smaller diameter than the same pitch 3 blade
13 1/4 seems like it isn't even intended for your 200.

 

[Texasmark]

I agree the 13+ diameters are made for the 4 1/4" gearbox like my 90 has. The 150+ use the 4 3/4 gearboxes and run the 14+ diameters. Not that you couldn't run the 13's. Just might not get the performance you thought due to mis alignment of the prop and gearbox. However, some "water over the blade" props like a cleaver run that way and apparently run just fine....there is no outer shell to the barrel of the prop so you have this step function from the housing to the widest diameter of the prop hub.

Authentication: All from memory and subject to err......so critics be nice. Grin

My 2c,
Mark

 

[baldben]

Thanks guys any clue on raising it or not and how to stop the cavitation on the take off.

 

[baldben]

Also since I have now where that will let me borrow a prop to run does anyone know what prop matches up with that setup? If I have to buy one I hope to at least get it close, thank you.

 

[steelespike]

If you want to stop the ventilation you need to start with a prop with the correct diameter.It appears your motor is rated for 5000 to 6000 rpm.
Increasing diameter may lower rpm I'm thinking a 25" or 26" pitch may do it.Stick with a 4 blade.
You might want to see if iboats will let you test props obviously there would be some shipping charges.
It seems to me I remember some sort of test program for expensive props.