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 Post subject: Re: Propeller Pitch - what it means and choosing the right one
PostPosted: Wed Aug 25, 2010 4:36 pm 
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Full Steam Ahead
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Joined: Wed Nov 18, 2009 4:13 am
Posts: 465
Location: Portland, Oregon, USA
Boat Name: Pond Skimmer
farmerden wrote:
Dietrich OK I tried that .I used 820 RPM,Ratio of 2 ,Pitch of 28 ,Speed of 7.1 MPH and that gave me a slip of .35. That is reasonablely close as using my GPS at 410 RPM ,pitch of 28,speed of 7.1 MPH I had calculated slip at 38. What I wanted to do was slow the engine down to 375 go to a 21 in D and a pitch of 24,same speed and the slip came down to .16.The reason for this is my boiler is maxed out,if I slow the engine down I should be able to run at a higher steam pressure which should make my compound run more efficiently and make up for the loss of power because of lower RPM's! Life is just one grand experiment isn't it? :lol: Den

Summer's well into it here in the great Pacific NW. :D Did you ever do the prop switch :?: What were the results :?: :?:

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 Post subject: Re: Propeller Pitch - what it means and choosing the right one
PostPosted: Thu Aug 26, 2010 4:00 am 
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Stirring the Pot
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Joined: Fri Nov 20, 2009 12:14 am
Posts: 447
Location: Shawnigan Lake B.C. Canada
Boat Name: Steam Queen
Just missed a 21"X24" 3blade on E-bay for $130.00 I was already bidding on a similar 4 blade-which I didn't get. But playing with a propeller works. Stan Knowles picked up a knot [3.5 up to 4.5] just by playing with the prop. I'm so busy building a new boatshop I haven't had much time to go boating this year! Den


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 Post subject: Re: Propeller Pitch - what it means and choosing the right o
PostPosted: Fri Dec 03, 2010 6:13 am 
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Stirring the Pot
Stirring the Pot

Joined: Fri Nov 20, 2009 12:14 am
Posts: 447
Location: Shawnigan Lake B.C. Canada
Boat Name: Steam Queen
It seems to me that those of us with a big fat keel [that's on the boat! no wise comments!] would do better with 4 blades than three.That would keep more blade surface out in the water instead of one blade hiding behind the keel Two would be even worse I think .Anybody have any experience with this? Den[img]
Image[/img]

If you can blow this photo up enough you can see one blade is totally hidden behind the keel and skeg


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 Post subject: Re: Propeller Pitch - what it means and choosing the right o
PostPosted: Wed Oct 26, 2011 8:46 pm 
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Full Steam Ahead
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Joined: Mon Nov 23, 2009 6:43 pm
Posts: 242
Location: Richmond Hill, Ontario, Canada
Boat Name: Cardinal Queen
So, if ihave a hull with a speed of 4.472136*1.34=5.99knots(6.89mph) my pitch should be 18". and the Diameter to run at 400rpm should be?


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