# Propeller and power from human

Discussion in 'Boat Design' started by Heiakon, Mar 10, 2005.

1. Joined: Mar 2005
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### HeiakonNew Member

I'm working on a schoolproject. We are designing a human powered boat. We're supposed to use Wageningers B-series propellers. The problem is that the BP value I find (to use in the Bp-delta diagram) is to low for the diagram. Of course I can tune the RPM so the Bp value fits into the diagram. But I wonder if there can be any better solution. Anyone who can give me a suggestion?

We tested power on a excercise bicycle, and we got 450 W out.. The boat shall be built for an competion. The boat shall go 200 m. So we count around 1 min time from start to goal.

We hope to get a speed up to 9 knots. Someone told us that CRP propellers can give us better effect... Is this true??

Hope anyone can give me something..

Greetings from Norway

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### CDBarrySenior Member

Get a copy of Principles of Naval Architecture (the current 3 vol set - you need Vol 2) through SNAME, probably by interlibrary loan. It has the algorithm to develop Kt, Kq vs J directly for B-series props.

A CPP prop probably won't help, since you are only interested in one speed point.

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### DavorNaval Arch.

Wageningen B series propeller

Send me some data of the boat:

Lwl, Bwl, T, T-transom, Cb, LCB.

Hull shape (V, U ) = ?

P= 450 W,

RPM= ?

D-prop=?

Distance of center of propeller to water line = ?

Send me this data and I will let you know what can be done.

rgds

Davor

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### jehardimanSenior Member

First, the Wageningen B series propeller is a pretty poor prop for human propulsion as the blade area distribution is all wrong. If you have to, use a B2-20 or so, pitch it well up, lower the RPM (about 200 max) to reduce losses, maximize the diameter, and DO use counter-rotating because it will get you better initial performance (I assume the 200m is from a standing start) from the human power so the added complexity is worth it. See if you can "bend" the rules and use the base Wageningen series to develop a better prop that the "standard" ones.

When designing a HPV prop it is important to remember that the torque curve of a human turning a crank is basically flat until you reach about 40-60 RPM and falls off rapidly to 0 at about 90-120 RPM. This is due to the energy expended in just moving the mass of the legs so get your propulsor into training now. Also make the prolulsor recumbent with a backboard and handgrips to allow him to overpush his weight. A gear shift is also helpful once the vessel is moving well to recover torque on the curve.

Try www.ihpva.org or www.foils.org for more on human powered vessels