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Old 29 May 2006, 06:11   #11
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Quote:
Originally Posted by codprawn
And why don't you just......
Just what, show you up for the fraud you are? 4500 posts and most everything is hearsay and 'googled'!

Quote:
Originally Posted by codprawn
Thanks for that - I made it perfectly clear that I hadn't experienced the prop myself YET. In fact the person who told me was someone I respect greatly and is VERY experienced - Bob at Shoreline - Suzuki main dealer.
Still it is pretty obvious which people on here have the "attitude" problems!!!
You miss the point entirely 'bubble-boy' I did not challenge Bob's opinions (who I happen to know!) rather the way you purport to be a world authority on everything without having any actual personal experience.


Quote:
Originally Posted by FreeTrader

Surely more blades = more drive in the water?
Err, not quite! What pitch is your 4-blader? If you were to add one inch of pitch you will reduce full-throttle RPM up to 200. The same theory applies by reducing the pitch by one. A 4-blade prop generally reduces the revs by about 100 rpm.
There are a number of good reasons for going to a 4-blade prop, if you have a 3-blade prop - all of this applies to your set-up, application and various other influences. A 4-Blade prop generally increases acceleration, cavitates less and handles better in the mid-range. Its the upper range you should be concerned with. As you reach higher speeds the extra blade(s) have served their purpose and drag etc come into play. As has been mentioned a thousand times, prop selection is a 'black art' and the correct prop for your craft should largely be determined on your application. For long-range cruising at higher speeds I would not necessarily chose a 4 -blade or Hi5 prop. Horses for courses!
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Old 29 May 2006, 06:21   #12
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Country: UK - England
Town: Leicester
Boat name: Vixen
Make: Ribcraft
Length: 6m +
Engine: Suzuki OB 175
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After advice we changed our prop from a 3 to a 4 as mentioned our horse wasnt right our course. Our boat is routinely loaded to near its stated capacity and we are not interested in top speed.

Having experienced the diffrences it gives our set-up the following advantages;

More torque - when fully loaded it still holds its RPM
It appears better on fuel but we didnt really have detailed figures previously
Doesnt get knocked off the plane as fast as the old one
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Old 29 May 2006, 06:44   #13
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Quote:
Originally Posted by Simon B
After advice we changed our prop from a 3 to a 4 as mentioned our horse wasnt right our course. Our boat is routinely loaded to near its stated capacity and we are not interested in top speed.

Having experienced the diffrences it gives our set-up the following advantages;

More torque - when fully loaded it still holds its RPM
It appears better on fuel but we didnt really have detailed figures previously
Doesnt get knocked off the plane as fast as the old one
Makes sense! You probably did the right thing.
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Old 29 May 2006, 07:03   #14
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Country: Belgium
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Engine: 250 HP E-Tec
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We replaced our 3 blade prop by a 5 blade prop.

Top speed with light load and perfect conditions remains the same (52.5).
Top speed with normal load (3 adults and 250l fuel) and normal conditions went up with (from 48 to 49).
Acceleration is much better + it's easier to reach the 45 kn bar and way faster to reach the top speed!
Fuel economy is more ore less the same.
Much more grip!
Planning at lower speed / RMPís


Paul
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Old 14 June 2006, 17:18   #15
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Country: Ireland
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Boat name: K'adů
Make: Redbay
Length: 7m +
Engine: Suzuki 300
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four blade results

Hi guys

Sorry I am so long in coming back but our local telephone lines were torn down by some kind trucker.

Regarding the prop change we got

Much better acceleration under full load
Maintain same cruising speed with lower revs( now maintain 30 knots @ 3800 rpm previously we needed 4200 rpm to maintain speed.
Boat appears to hold speed better in the rough.

Further feedback later

Rgds
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