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Old Mar 25, 2012, 07:24 PM
KFC
Blue Foam Master!!!
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United States, KY, Hanson
Joined May 2007
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Question
Prop advice

So about a month ago I bought a Spartan as a noob FE boat. I have since beefed up the cooling system and am pretty satisfied so far with the performancse. My problem at this point is that a buddy of mine also got one and when we get together next month at an undisclosed R/C event, I need to have the faster boat. Can anyone offer me some advice on a substitute prop that might give me the edge, even if it shortens the runtime. Should I go with a 3 bladed prop or a 2 bladed prop? Beryllium copper or plastic? Basically how do you go about selecting props for boats. (I know how to do this for airplanes, but I get the impression that boats are a whole different kind of animal). What I really want to walk away with here is an understanding of how to select a prop for a given power system, so explanations of the reasons behind any suggestions would be greatly appreciated.
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Old Mar 25, 2012, 07:32 PM
I feel the need for speed!
scorpion1's Avatar
Southern U.S.
Joined Jun 2008
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If you are running the new castle system i would give an s220 a try.

http://www.offshoreelectrics.com/pro...i-prather-s220
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Old Mar 25, 2012, 09:03 PM
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Joined Jul 2008
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Beryllium same as the Prather prop, as that SS one is out of stock balancing is the same as for aircraft and sharpening is the best you can with what you have (keep kids away from the dust or wet sand), once you cut yourself as you install or remove it its perfect.
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Old Mar 25, 2012, 09:17 PM
KFC
Blue Foam Master!!!
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United States, KY, Hanson
Joined May 2007
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The electronics are all Castle and I bored out the water pickup and installed large bore tubing through the whole thing to help keep it cool.

Is there a formula or something that you guys use to pick the props, or is it just experience?
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Old Mar 25, 2012, 10:33 PM
I feel the need for speed!
scorpion1's Avatar
Southern U.S.
Joined Jun 2008
7,086 Posts
Quote:
Originally Posted by KFC View Post
The electronics are all Castle and I bored out the water pickup and installed large bore tubing through the whole thing to help keep it cool.

Is there a formula or something that you guys use to pick the props, or is it just experience?
There are loose parameters for recommendations, but i mainly shoot from the gut now.

Think about all the different variables in choosing a prop.

Hull length
Hull width
Hull type
Motor KV
Motor size
# of cells
Total rpms
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Old Mar 26, 2012, 08:49 AM
KFC
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United States, KY, Hanson
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Will I get more stability (less rocking at speed) with a 3 bladed prop? Would I need to go to a smaller diameter?
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Old Mar 26, 2012, 12:14 PM
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Canada, ON, Markham
Joined Aug 2008
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Rocking back and forth gently comes from the hull riding higher out of the water, which just comes with speed. If its rolling to one side harder, or the transom is jumping around then it might be better with a smaller diameter prop. A higher pitch, or 3 blade will likely help that a bit.
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Old Mar 27, 2012, 08:37 AM
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Gordonsville,Virginia
Joined Nov 2009
335 Posts
Some good advice and a good prop chart . www.offshoreelectrics.com/propeller-chart.php
Just remember to start out small and work your way up .
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