# How can I calculate the size of paddle wheel?

Discussion in 'Hydrodynamics and Aerodynamics' started by refael, Jan 15, 2018.

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1. Joined: Jan 2018
Posts: 3
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Location: isreal

### refaelNew Member

I need to build a boat with 2 6V motors with 185rpm and 1.5 [kg * cm] torque.
the total Weight of the boat is 3kg.
got double hull boat length of 60cm and width of 7cm each
probably I will use paddle-wheel because low rpm.
How can I calculate the size of the paddle wheel?
i look at the books and i can not understand how to calculate and design the paddle-wheel.

2. Joined: Jun 2017
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Location: Denmark

### Gunnar SommerlundMarine Engineer

Here is an idea. if you know your shaft torque, find the power available at paddle max distance . Then isolate the area in displacement formula . its no where near a perfect example but should do just fine for what you need

I can find the equations you need once i get home. Let me know if it still bothers your.
rewrite Vdispl as a area time length .

3. Joined: Jan 2018
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Location: isreal

### refaelNew Member

i would thank you if you share the right equations..there are too much information in the books so i don't know what to use.
thank you a lot!

4. Joined: Jun 2017
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Likes: 5, Points: 8
Location: Denmark

### Gunnar SommerlundMarine Engineer

5. Joined: Jun 2017
Posts: 32
Likes: 5, Points: 8
Location: Denmark

### Gunnar SommerlundMarine Engineer

Dont take it as a awnser this is my aproach to your problem with some predefined variables such as diameter and arc lenght.

it might not be truth, but all the equations you need to solve the problem should be there.

i did a quick google search and were able to find quite alot information to your problem.

My aproach is just a educated guess from my background as a marine engineer and i choose to handle this problem by simplying it, rather too much =). efficiency is not taken into account and instead of (g) you are probably gonna use water friction. Since my calculation concern of moving water up! witch is not your case.

Last edited: Jan 16, 2018
6. Joined: Jan 2018
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Location: isreal

### refaelNew Member

Thank you so much.. It will do the job.

7. Joined: Jun 2017
Posts: 32
Likes: 5, Points: 8
Location: Denmark

### Gunnar SommerlundMarine Engineer

www.engineeringtoolbox.com

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