# How to cal. Estimated power at the propelleer

Discussion in 'Boat Design' started by Adeyele, Apr 15, 2013.

1. Joined: Jun 2012
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Dear all,

Can anyone help me on how to calculate this:

A vsl is 30mtrs in lenght, with froude no of 1.49, wetted surf. Area is 160.54, spd 8kts, frictional rest. Is 67.8, Admiralty coefficient is 383.45. Using this fig. How can I estimate d engine power?

Regards
Mike

2. Joined: Aug 2002
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### gonzoSenior Member

The power at the propeller is whatever you input on the shaft. The power the propeller can absorb you can get from the manufacturer's charts.

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### jonrSenior Member

Maybe he meant "estimated power needed" to achieve the 8 knots. My guess - tow it and measure the force.

4. Joined: Jun 2012
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Location: Lagos

Helo Gonzo,

This is a calculation exercise so I wasn't given the details. All the figures are based on assumptions.

Mike

5. Joined: Aug 2002
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Location: Milwaukee, WI

### gonzoSenior Member

Then you need to follow the rules and assumptions of the exercise. For example, do you use 90% of maximum power for calculations?

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