...The density of sea water is 1000x that of air, and it's not uncommon to see currents over 0.5 mph over 18 hours a day under bridges or other restricted flow areas. Since the Magnus effect is linear to fluid flow; just multiply the numbers in the other post by 1000.

How is it I never ran the numbers here?

F/L = ρv 2πr²ω, where r is the radius of the cylinder and ω is the cylinder rotational speed.

So, if the cylinders had a 1' radius, then for 1m cylinder length at the power is:

Code:

```
power kW, cylinder revolutions per second
flow, mph flow m/s 0.25 0.5 1 2 3 4
.25 .111 .06 .117 .236 .471 .705 .942
.5 .237 .126 .252 .5 1 1.5 2
1 .447 .237 .474 .949 1.9 2.8 3.8
2 .894 .474 .949 1.9 3.8 5.7 7.6
3 1.341 .711 1.4 2.8 5.7 8.5 11.4
```

From the table in the OP the water speed is between .5 and 1.5 for 2 hours/d, so at an average of 1 mph with a 1 revolution per second would generate 12 kWh per cylinder/d. Rougher is supposed to be better, so perhaps fouling wouldn't have a big impact. I could see a revolving line of these under bridges. Easy to adjust the power output by altering the spin rate.

Let's change the units to revolutions per minute but keep the diameter and length the same for the 1 mph case:

Code:

```
power W, cylinder revolutions per minute
flow, mph flow m/s 1 5 10 15 20 30 60
1 .447 16 79 158 237 316 395 949
```

Using the same case as above, let's increase the radius from a foot to a meter:

Code:

```
power W, cylinder revolutions per minute
flow, mph flow m/s 1 5 10 15 20 30 60
1 .447 76 378 757 1135 1513 1891 4540
```