Here's an inherent difficulty of tidal generators: you know how a tide chart is basically a sine wave, showing min/max peaks every six hours? There's another sinusoidal graph about 90 degrees out of phase with that chart representing
speed of the water. Its peaks coincide roughly with the midpoints between high and low water. Like tossing a ball into the air: it's moving max speed when it leaves your hand, then it slows and slows until it nears its peak, then it stops and seems to hang there for a bit, then it begins accelerating until it reaches its initial speed as it passes your hand. If you were standing on a cliff edge and the ball were on a bungee cord, it would perform the same trick downward: max, fast, slower, slow, stop, slow, faster, fast, max....
Why does that matter? It means in a location prone to 5kt tidal rips, the water will spend almost all its time moving slower than 5kts. Most of its time moving
much slower than 5kts. Power available in a moving fluid is the cube of the fluid's velocity -- air moving half as fast has one quarter the kinetic energy and one eighth the power. So when that tidal rip is below its peak (moving 2.5 kts, say), it just doesn't have very much power in it for you to gather, by any means you can think of. Output falls off very steeply as fluid speed diminish; and as mentioned above, tides spend most of their time moving slower than peak speed. A tidal generator will spend 1/3 of its life doing nothing at all, 1/3 doing a little bit, and 1/3 cranking like a sumbitch.
Will that last third make up for the other 2/3rds?
That's why you need to ignore peak output on wind turbines (or the OP's device). Don't be too impressed by that instantaneous amp meter reading as the turbine maxes out in 25kt winds or the Magic Box pendulum achieves peak acceleration. What really matters is
output over time in a given regime. How much power will the Magic Box generate in a moderately sheltered anchorage in 24 hours of normal swell? How much juice will the wind turbine generate over one month in a location with mean wind speeds of 10kts?