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I am currently in Indonesia with fellow students working on a project to experiment and build an alternative energy source to propel boat with optimal efficiency and also to minimize the use of diesel and petrol to combat pollution and limit the use of natural resources.

My team intend to develop a solar powered battery for a single deck river boat commonly used as inter-island and river transport.

I hope you all are able to provide some insight and advise on how I can proceed with this project. The only problem I had is the math to calculate how much watts is needed to optimize the boat movement. In theory is it possible for a simple solar panel set up to power the motor system of the propellor.

THANKS!!

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    $\begingroup$ I'd start by trying to measure the drag coefficient of the boat in a flowing river. Measure the speed of the water. Hold the boat by rope in various flow rates and measure the tension in the rope (newtons, N). That will tell you how much power would be required to drive the boat at that speed through still water. You'll need additional power to actually accelerate the mass of the boat and more again if you wish to be able to motor upstream against the current. $\endgroup$
    – Transistor
    Nov 11, 2023 at 17:02
  • $\begingroup$ the title of your post does not match the implied question $\endgroup$
    – jsotola
    Nov 11, 2023 at 17:06

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You begin by studying a typical boat to determine how many horsepower its engine is developing when it is cruising at its typical speed. Let's say it uses a 5HP gas engine driving a straight-shaft propeller and it is running at full throttle. One horsepower equals about 750 watts continuous so it takes 3750 watts to propel the boat at cruise.

Now you look at how many watts there are hitting one square meter of area on the earth's surface. This is actually 1380 watts. A solar cell can only convert about 20% of that number into useful electrical power, so a one meter square cell will yield no more than about 750 watts (one horsepower!)- assuming perfect conditions.

Now we feed that 750 watts into an electric motor which is about 85% efficient so you get 640 watts on the output shaft.

Now you solve for the number of square meters of collector area needed to get you up to 3750 watts shaft output! This calculation will furnish an absolute best-case estimate and in real life, you'll need more area than that to do the job.

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  • $\begingroup$ 1380 Watts is outside the atmosphere, average irradiance at the Earth's surface is about 1000W / m^2. $\endgroup$
    – Solar Mike
    Nov 12, 2023 at 18:53
  • $\begingroup$ @njuffa and affected by cloud etc… but your 1000 is the same as my 1000… $\endgroup$
    – Solar Mike
    Nov 13, 2023 at 1:08

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