Bob, I think he indicated a prop RPM of 1000 not 6000. Does that change the speed? Not many Tartan 27s are ever going to do 11 knots.
From: electricboats@yahoogroups.com [mailto:electricboats@yahoogroups.com] On Behalf Of Robert Lemke
Sent: Wednesday, March 12, 2014 10:04 AM
To: electricboats@yahoogroups.com
Subject: Re: [Electric Boats] someone check my math please
Luke,
My math (w/o knowing the slip component, so not factored in) is 11 kt @ 6000 motor rpm.
Bob
From: "luke.wolbrink@gmail.com" <luke.wolbrink@gmail.com>
To: electricboats@yahoogroups.com
Sent: Wednesday, March 12, 2014 9:47 AM
Subject: [Electric Boats] someone check my math please
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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