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NEED HELP WITH RUDDER LENGTH!!

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Old 04-27-2012, 01:06 AM
  #1
8MILLSNIPER007
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Default NEED HELP WITH RUDDER LENGTH!!

I need help figuring out the right length my rudder needs to be for one of my boats. The boat is 31 inches long and is a deep vee hull with a sub surface drive. I lost the rudder that came with it and the boat has been in dry dock (sitting on my shelf) for about 12 years. I decieded it's time to get her back in the water again. I have a rudder that is 4-1/2 inches long but it looks really long when I put it on the boat. It looks like at least 4 inches of the rudder would be under water if the boat was up on plane.
The boat is a Prather commander deep vee if anyone is familar with it.
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Old 04-27-2012, 06:42 AM
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Default RE: NEED HELP WITH RUDDER LENGTH!!

You can hacksaw some off. 1 1/2" -2" below the prop is good. ,File a Vee to the bottom you just cut. Stay below the water intake if you have one.
The props dia is used the 1 1/2 -2" NOT the CL of the driveline. Sorry I didn't mean to confuse.
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Old 04-28-2012, 07:49 AM
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Default RE: NEED HELP WITH RUDDER LENGTH!!


Quote:
ORIGINAL: 8MILLSNIPER007

I need help figuring out the right length my rudder needs to be for one of my boats. The boat is 31 inches long and is a deep vee hull with a sub surface drive. I lost the rudder that came with it and the boat has been in dry dock (sitting on my shelf) for about 12 years. I decieded it's time to get her back in the water again. I have a rudder that is 4-1/2 inches long but it looks really long when I put it on the boat. It looks like at least 4 inches of the rudder would be under water if the boat was up on plane.
The boat is a Prather commander deep vee if anyone is familar with it.
Hi 8MILLSNIPER007
Of my 3.5c.c. boat tail....Rudder.Is 2.5 inches below the water.
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Old 04-28-2012, 02:18 PM
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Default RE: NEED HELP WITH RUDDER LENGTH!!

OP is asking for a sub-surface rudder ! ! !

For sub-surface a rudder as deep as the prop .. and 1/2 of the length as width should be OK.

See bottom of [link=http://www.prestwich.ndirect.co.uk/hdwrrubbersetc.htm]T H I S[/link] page.
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Old 04-28-2012, 05:26 PM
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Default RE: NEED HELP WITH RUDDER LENGTH!!

This was my 2 nd built hull a Dumas Comp .21 Sub surface turned on a dime. the hull is close to 15 yrs old. or more. I've never seen a rudder built like that since.
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Old 04-28-2012, 08:42 PM
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Default RE: NEED HELP WITH RUDDER LENGTH!!

Thank you all for your input. I have put up some pics of the boat and rudder, one thing I know for sure is I am gonna have to cut some of the rudder off. This boat is a subsurface drive 31 inch that I put a OPS 40rotary intake, rear exhaustengine in and I am not too worried about the rudder slowing the boat down, that might actually be a good thing.
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