Labbed ? on 34 pitch 502mag efi

30 lab bravo 1 4 blade, I hit my rev limiter that is 5400 ,very hard to blow out or slip. 85 on gps 1/4 trimmed up on gauge
32 natural bravo 1 4 blade slips a little more, hit rev limiter 89 mph 1/4 trimmed up
34 natural bravo1 plained out every time. Seems like I could blow out if I wanted to,when boat airs out prop slip goes way down, 5000-5100 rpms 91 mph trimmed to 1/2 on gauge.
Would labbing the 34 help the prop bite the water better and not want to slip as much when the boat is not aired out.Thanks for the info. 2000 daytona

[PowerboatsNW]

Assuming you are running a 1.5 gear ratio you are running 19%-20% slip any way you look at it. Do you have a nose cone on you drive? You need one if you do not.. Does the boat ride on the nose real hard if so lower the X dimension a bit. Yes adding some cup to the prop would help however those other issues need to be covered first before you mess with props. 19%-20% slip is horrible for a cat.

1.50 gear ratio, no nose cone. How much do you think a nose cone would help? My out drive is 2 inches below rubrail with a standard lower. Single step 25 daytona.

I used the bam prop slip calc and I got 15 % . 5000 rpm 91 mph 34 pitch. I am not really unhappy with the top end, I know that my rev limiter and motor limit my rpms to go any faster. What I was wondering is I can tell the prop is slipping alot (you can even see a small rooster) until the boats up and moving pretty good,then the prop bites and the boat takes off quick.I think it starts to bite when the boat is starting to air out. 2 people 70 gallons of fuel.

[PowerboatsNW]

I have done plenty of hydrodynamic testing, you need a nose cone? If you try to get a prop to work with what you have things will be different when you install a nose cone. Is it 5000 rpm's or 5100. The best slip factor is 17% at 5000. 19.5% at 5100.

[throttleup]

blownboat,
A 34 Bravo 1 lab finished on your boat will be more difficult to get on plane. A prop lab finished for speed has less cup than a stock prop and will probably be more difficult to get on plane than a stock prop.

On your application the slip isn't really that bad for a Bravo 1. You really need a 5 blade prop. The 5 blade will get the boat on plane very easily and I wouldn't be surprised to see an increase in the top end as well as having all the benefits of a 5 blade prop.

Matt

What do you recomend in a prop. I cant spend $5000 on a hering prop. Thanks for your advice. If I can spin the 34 to 5100 rpms do you think a 5 blade will bog me down, what pitch do you also think I should try.

[Turbojack]

What is the center line of your prop compared to the lowest part of your sponsons?

I havent measured it. I do know the standard bravo is 2 inches below rubrail on a single step 25 daytona.I am at work now but I will measure it tomorrow.

[throttleup]

I would start with a 31 or 32 pitch 5 blade. I would guess the 31 5 blade would give you about the same top end numbers as the Bravo 1 34, 5100@91. If you pulled that to the rev limiter then go to a 32.

The 5 blade will not bog the motor down but actually wake it up. The acceleration will noticeably improve, cruise speed will increase 3-7mph, the boat will run smoother and handling will improve.

A stock Mecrury or Hydromotive 5 blade will set you back less than $1000. The only downside to the Maximus is that it needs to be lab finished to run well so that adds to the price.