Wednesday, March 12, 2014

Re: [Electric Boats] someone check my math please

 

Ned,

Curious about your math.

1000 rpm X 13" = 13000" per minute / 12 = 1083' per minute X 60 = 65000' per hour / 6076 (ft per nm) = 10.7 kt. w/o slip.

Bob


From: Ned Farinholt <nedfarinholt@comcast.net>
To: electricboats@yahoogroups.com
Sent: Wednesday, March 12, 2014 12:23 PM
Subject: Re: [Electric Boats] someone check my math please



Luke,
1000 rpm and 13" pitch is about 7 knots with no slip.
Ned

On Mar 12, 2014, at 12:47 PM, <luke.wolbrink@gmail.com> wrote:

 
Almost done installing everything on my Tartan 27 sailboat and spring is running out fast. I've installed a HPM5000 motor from golden motor (5kw) on my 7400# sailboat with LWL of 22' and beam of 8.5 (not sure at the water). I've replaced the propeller with a 13x13. The max RPM is 6000, so I'm going with a 5.83:1 drive ratio to get my prop speed down around 1000. From what I've calculated using Douglas Little's book this seems to be about right. However it seems too slow. any feedback on my math would be appreciated.

thanks in advance,
Luke






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