Four or Five Blade

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04-13-2009, 08:34 PM

#31

jdnca1

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Quote:

Originally Posted by stormbauer

Well that is very interesting information. My situation is that my 33 will run 125 at 5,800-5,900 RPM with current 30P Bravo's (non labbed). The motors are 920 HP at 5,700 RPM and put out 890 Ft#'s ! So far draive has been on - Teague's. I do not want drive problems but would like to get up around 130 ish. Like I stated boat gets up on plane easily.

Part of the reason it comes up easy are the 30P props. Storm you must be running a 1.21 (or lower) drive ratio if you are seing those speeds at that rpm with 30's. I run 1.21 with labbed 33's (30's pitched up)

What engines are you running? Hydralic or solid roller cams?

Ther higher X's in the newer boats are definately part of the reson they are so fast...and why 5 and 6 blade props are required. I know someone with a 33 dyatona that runs 6 blade herrings and has a hell of a time getting up on plane..

04-13-2009, 08:37 PM

#32

jdnca1

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Quote:

Originally Posted by CheckedOut

This brings up a good point, well more of a question really. Is there a certain point (power wise) where 4 blades are impractical? It seems like all of the big power cats and most everything running with sixes have five blades. Do four blades just slip too much to be useable once you pass 700 or so hp?

I don't think so, it's more of where do you run out of pitch for a given rpm target...and gear ratio. Once you go above 32P bravo's they start getting tougher to get on plane due to the angle on the blades...36p bravos are sweet props...but a bear to get on plane in many applications. The props don't care how much HP is on the input side...