PanteraInVentura

I need help with prop selections. I have a 1981 24ft Pantera with 454 (450hp) with a Bravo 1 drive running a 23p Quicksilver 3 blade. I ran 54 mph on GPS @ 5200 rpm with a 4 adults averaging 190lbs. I usually run with a load of people. Can anybody tell what props I should go with or what sizes i should expirement with.

What kind of mph should I expect with a heavy load and a light load.

Thanks for any help.

IRONMAN

Check your tachometer, if you have a 1.5:1 ratio bravo then your slippage is about 28 percent and that is way too high. With my 24 I get 11 percent slip with the bravo1 prop and about 9 percent slip with the Hydromotive 3 blade. That is with 2 adults and gear approx 400lbs total with a full tank of fuel at WOT. I have a TRS drive so your numbers will vary some. So What is next? I would get a verified tach reading and go for a bravo1 four blade in 24 or 22 pitch depending on where the motor makes power. If you load the boat the 4 blade is the way to go. if you go too big in pitch you can have it lab finished to gain some RPM's
good luck, The Ironman.

PanteraInVentura

Thanks Ironman

This gives me some place to start. Can to high of a x dimension cause this much slippage or is it my prop that i am using. It needs to be tuned I have some minor nicks.

I took my Pantera out for the first time in big water 3 to 4 ft and your right "the rougher the better". Man what a blast.

Thanks again!

JO - PANTERABOATS

Pantera in Ventura,


At what drive height is the Bravo 1 cut out at on the transom.What Ironman answered you in his last email is correct.

If you can get your hands on a 4 blade bravo 1 prop go ahead and give it a try.This will drop your slip and increase spee and acceleration.

I run many new 24s with 3 blade Mirage props.I am sure your boat had a TRS drive on it fo many years and converted to a Bravo 1 drive.The X dimension is very important when it comes down to your boats performance.

Another will be to try a drive spacer and lower the drive down.

With a 23 pitch Mirage at 5200 RPM with a 10 percent slip you should be in the 72-73 MPH range in ideal conditions.

By having alot of slip your RPM will increase but not give you forward push out of your prop and less speed.To low and you cause added drag and decrease speed and acceleration.

Let me know if I can help you with anything.

Regards, JO

PanteraInVentura

Hi Jo,

Thanks for your help. Can you tell me what the optimum drive height is for the 24ft with Bravo Drive. I am hoping it's just a prop problem.

As soon as I get pics i'll post on your website.

Thanks!

GaryMMM

If you are sure of your horsepower and you tach, something is really wrong. The x-dimension cannot account for such poor performance. It is very unlikely but check to see if the hull is straight. A bad rocker or hook can really hurt. Either condition can be repaired. Next check for weight distribution. Too much weight in the bow can really hurt too. Once this is all checked out and if you are on a budget, try a 26" Hydromotive 3-blade. I had a 1991 24' with 365 HP / Bravo I with a 24" Hydromotive and it ran 68 mph in the hot Miami air. I now have a new 24' with a single 250 Yamaha and it is fast for a single. Good luck. GaryM

JO - PANTERABOATS

It sure can!!! Been there,done that. Jo

Caincando1

Isn't a Quicksilver a smaller diameter than a mirage? I think so but i'm not sure. You are probably running to small of a diameter which will increase slip alot. Generally quicksilver are for light boats with a shallow V. Definalty not a Pantera prop.

JO - PANTERABOATS

Hey Pantera in Ventura,


We mount the Bravo 1 drives at a 17 X dimension.

I measured a new 24 I have here and if you were to take a tape measure from the bottom of the hull ( underneath drain plug ) to the where the tape measure would hit the transomplate you would have 8 1/4 inches.

If your tach is reading correct and you are turning a 23 pitch mirage at 5200 RPM you would be running 72-74 MPH with a 10 percent slip.Now if you GPS your boat and is showing 54 MPH then you have huge slip due to the prop or drive height being set to high.

No matter what if you turn pitch and RPM it gives you your speed.If you have a hook or your down on power you could not turn the prop at 5200 RPM unless you have slip or your tach is not reading correctly, or you are not giving the GPS enough time to give you an accurate top speed.

Try a 3 blade Mirage between a 23 or 25 pitch or a 4 blade Bravo 1 between a 22 or 24 pitch and let me know what it does and how the boat reacts to the 4 blade.

I will give you an example on how important drive height is.Last year I set the drive on my Black F1 28 race boat a liitle high and decided I would work my way down searching for optimum performance.

By lowering the drive from 20 to 19 on the x dimension with a 1 inch spacer we ran from 73-74 to 79-80 MPH on GPS. What happend was that the prop had to much slip and the drive would not have enough leverage to carry the bottom of the boat when trimmed out.We could still turn the props at high rpm on the limiter but we did not have forward push out of the prop and added wetted surface from the hull which increased drag, and slower speeds.

Stay in touch!

Regards, JO

PanteraInVentura

Hi Jo,

I checked my x dimension and it's at 8 inches. I am looking into getting a four blade and giving it a shot. This weekend i'll have my mechanic double check the rpm's. I'll keep you informed.

I am so new at this but these are fun problems to solve.

Thanks for all your help!