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09-01-2006, 07:50 PM #1Junior Member
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Calculating speed with prop pitch number
Will someone tell me how to calculate the resulting speed with a numbered propeller pitch number, combined with horsepower and boat length? Is there some formula? My boat is 21 ft w/260hp, and has 24 and 26 prop pitches. Does the higher the pitch # mean higher top speed, vs slower acceleration?
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09-01-2006, 07:57 PM #2
Calc prop slip here with RPM, GPS speed and known pitch.
http://www.rbbi.com/folders/prop/propcalc.htm
There is no perfect formula, too many variables. Somewhat identical hulls can sometimes vary by several hundred pounds, for example.
If you want more performance, start a new thread with a title like "more speed from xxxx" and say what exact make/model hull and motor you have, setback, height, etc.'89 Hydrostream Vegas XT, '90 Merc 2.4 Bridgeport PCU EFI
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09-01-2006, 08:09 PM #3Junior Member
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propeller calculation
thanks for the info, my boat is a 21ft Eliminator with 260HP Mercury 2.5 outboard, I have two props, a 24 pitch and a 26 pitch prop, any speed estimates, lastly what would a 32 pitch give me? I haven't run this boat yet, first high performance boat.
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09-01-2006, 09:24 PM #45000 RPM
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Read all the links I provide:
http://go-fast.com/prop_slip.htm
http://go-fast.com/boat_speed_predictions.htm
http://go-fast.com/Prop_Slip_Calculator.htm2003 21XDC Bullet
2003 250 V-Max
28TXP 6000 @ 87.0 gps light load
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09-01-2006, 09:29 PM #5
Your boat will probably run mid to high 80's with the 24 or 26 prop
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09-02-2006, 07:43 PM #6Junior Member
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my boat speed
Sounds about right, former owner told me 80 to 88mph with 24 and 26 pitch props, by my calculations then a 32 pitch prop would give me a 100mph? Just for curiosity, twin 260's on a 21ft eliminator, would they push the boat to about 130 mph?
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09-02-2006, 07:59 PM #7
The 32 will only push it to 100 if you have at least 300hp. Twin 260's will normally get you into the mid teens. Mine on my 21 Liberator have been modified, and will run mid 120's.
" IT'S NOT HOW FAST YOU ARE, IT'S HOW COOL YOU LOOK!!! "
Check out my new website. liberatorpowerboats.com
Boat Delivery available
Things owned. NOTHING!!
Ain't got no toyz, Ain't got no money! I is jus a poor Florida boy!
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09-03-2006, 12:14 AM #8Junior Member
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32 pitch prop
So maybe the 32 will get me to 93-95mph? But this prop will cut my acceleration down, unlike the 24 pitch prop?
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09-03-2006, 06:48 AM #9Originally Posted by 928man
Originally Posted by 928man'89 Hydrostream Vegas XT, '90 Merc 2.4 Bridgeport PCU EFI
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