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Old 28 April 2007, 16:00   #21
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Country: UK - England
Boat name: Seashell
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Length: 7m +
Engine: Inboard diesel
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Thanks for that Vince; was the answer I was looking for. I currently reach top revs perfectly with my 3 blade so I guess I'm looking at a 14x16 4 blade?
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Old 28 April 2007, 19:58   #22
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Country: UK - England
Town: Dorset
Boat name: Pending
Make: Pending
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Four Blader

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Originally Posted by Tim M View Post
Thanks for that Vince; was the answer I was looking for. I currently reach top revs perfectly with my 3 blade so I guess I'm looking at a 14x16 4 blade?
Hi TIM,
I too have been testing out props the last two weeks here are my findings:
Boat Ribcraft 4.8
Engine Yamaha F60

ALLOY 11.1/8X13 3 BLADE----6000RPM-----32KNTS V-GOOD OUT OF HOLE PERFORMANCE

ALLOY 11.5X14 3 BLADE------6000RPM-----35KNTS POOR OUT OF HOLE & MID RANGE PERFOMANCE

STAINLESS 10.5X15 3 BLADE--5600RPM-----36/37KNTS V-POOR OUT OF HOLE PERFORMANCE

STAINLESS 10.5X14 4 BLADE--5800RPM----34/35KNTS GOOD OUT OF HOLE EXELLENT MID RANGE

ALL DONE WITH HALF FUEL (45LTR) MEASURED UP & DOWN WIND & TAKING AVERAGE OF BOTH RUNS.
I HAVE FOUND THAT I HAVE HAD TO MOVE THE ENGINE UP 2 BOLT HOLES WITH THE STAINLESS PROPS TO GET THE TOP END PERFORMANCE BUT THEY STILL DONT CAVITATE ONLY ON EXTREAME CORNERING (JUST TRIM IN TO CORNER, SHOULD DO ANY HOW). CURRENTLY RUNNING STAINLESS 4 BLADE 10.4X14 WITH TIP OF PROPS UPPER MOST BLADE LEVEL WITH BOATS KEEL, LOADS OF GRIP LOW DOWN & MID RANGE WITH A V-GOOD TOP END FOR SIZE OF BOAT/ENGINE...NOW HAPPY!
THE 4 BLADE PROP IS A SOLAS STEEL DEVELOPMENTS TROPHY SPORT (MERCURY) 410.08 INC VAT, YOURS SHOULD BE LESS AS IT WILL BE STANDARD MERC & NOT A RE-BOSSED ONE LIKE MINE TO SUIT A YAM. HOPE THAT THIS INFO HELPS, LET ME KNOW HOW YOU GET ON.
MIKE.
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Old 28 April 2007, 20:07   #23
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Country: Ireland
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Boat name: rockhopper
Make: ballistic
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Bless your tenacity Mike with the spike,,,
Can you come and do my boat when i get it....

good work
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Old 29 April 2007, 07:01   #24
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Country: UK - England
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Proping

Hi everyone,
If everytime someone got a boat they made a quick note of the,
boat,
engine,
prop/size & type,
WOT,
Fuel on board,
Passengers,
Performance,
& if trying out new prop's, show the difference....
then posted it on here on a dedicated thread then it would make life a lot easier for anyone to make a good calculated guess of where they should be with a resize, i tried the manifacturer but although very helpfull they where non-commital which is understadable as they i suppose they have not carried out & kept records on each model with various options, its a mine field for them! I did find 'Steel Developments' very helpfull & might still go back & have 1/2" of pitch taken off just to reach top RPM. I am no guru on the subject just lucky to get where i wanted after trying only 4 props.
Mike.
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Old 29 April 2007, 16:30   #25
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Country: UK - England
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Spike

Your idea of having a central data base which everyone can add and refer to is great. How do we make it hapen?

Jon
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Old 29 April 2007, 19:26   #26
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Prop Database

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Originally Posted by Jon.esp View Post
Spike

Your idea of having a central data base which everyone can add and refer to is great. How do we make it hapen?

Jon
Sorry Jon i have no idea, would have to 'pm' the administrator, but im up for it & i think it would be a great help to everyone as a guide line (sure would have saved me a lot of time).
Mike
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Old 13 May 2007, 12:49   #27
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Country: USA
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Hey guys!

Also, using a four blade prop, there is less torque or felt pull to one side through the steering mechanism such as a tiller handle. I have a 60 HP Mercury, and while using a four blade prop, I have elimated all steering torque. I can let go of my tiller handle, and the boat will run straight.





Mike
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