682gold

iTrader: (3)

I know you can run different pitches on your prop but can you run bigger diameters on the same outdrives? Pitch is the amount of angle or grab a prop has on it correct? thanks in advance for the replies.

demag67

i think you will have to give a little more information as to what you are looking to do and what your current setup is. depending on your setup you may be able to run a larger diameter prop.

Griff

Pitch is the distance the prop would move forward through the water with one revolution.

Bigger pitch moves forward more, but also take more HP to spin.

A.O. Razor

Yes you can run different diameters. The B1 drive accepts prop's up to 16". Different prop models have different dia. In some cases like with the Mirage+ different pitch props also has a different dia. Pitch is the theoretical distance a prop will travel through the water in one revolution. A 28 inch pitch prop will travel 28 inches through the water pr. revolution in theory. This won't happen in real life though because of prop slip, and you need slip to get the boat moving.

682gold

iTrader: (3)

The props that are on my Hallett 300 are a Hydramotive Q-IV 15-1/2" 27P My RPMS at WOT are 4800 Can we get mor speeds with a 28P prop? Where to go from here?

A.O. Razor

We'll need more info.

Motors: make/model/hp/max rpm range.
Current max GPS speed.
Drive gear ratio.

DirtyJerz

I do not want to hijack this thread, but I see a lot of good info here and figured I would ask.

Theoretically, by increasing the pitch size of a prop, will that in turn increase the amount of torque on the drive componets (gears, etc.)? So if the drive is the weak point (bravo x or xr drive on a 600 + horsepower engine) will putting a bigger prop on increase the amount of strain on the drive?

Griff

Call BBlades. I really don't know what style of props should be on your boat. The Q IV's are a stern lifting prop.

Like was posted, it depends on what engines are in your boat and what the recommended WOT is for the engines. A 1" increase in pitch will generally reduce your rpms by 200.

Griff

The boat needs to pitched for the proper WOT running of the boat. A bigger prop is harder to spin, so yes it will put more strain on the drive. In the same regard, you need more HP to turn the bigger prop. Its kind of like what came first, the chicken or the egg???

DirtyJerz

Griff,
Thanks for the response! The reason I ask is b/c I have a 30p prop on a xr drive behind a ~850hp engine. Im very gentle on the sticks and just opened the drive up and the gears look great! Problem is I cant run wot b/c the rpms get up to around 6400. I really dont want to run the enigne that high and would like to stay around the 5900 area. Thinking of going up to a 34p to see where that puts me rpm wise. I know the engine can spin it, but wasnt sure of the additional "theorietical" stress it would put on the drive.