Might this be cost effective ?
http://www.sciforums.com/attachment.php?attachmentid=2913&stc=1

Where's the jpg?

Where's the data about how much it would cost to build, how long it will last what is the power output, what's the anount of hydrogen that will be produced daily???

Where's the data about how much it would cost to build... The marine engineers and power company can figure that out. ...how long it will last... That's incidental. As proof: how long will a nuclear power plant last? ...what is the power output... That is, in fact, given in the picture. ...what's the anount of hydrogen that will be produced daily??? The theoretical amount of hydrogen produced can be figured by applying the thermodynamic efficiency of electrolysis to the power produced. The actual amount of hydrogen production can be figured by applying the known efficiency of actual electrolysis machines.

Harnessing the power tides is a good idea, period. The question is execution: how are you doing to do it? I'm unsure the assembly of pulleys depicted will work. Elaborate and explain how it all works, if you will.

I don't see how it would work at all.

It’s just an idea I wanted to throw out there.
My WildAssGuess on the drawing has it making 75kw but I think windage losses might make it more like 50kw. Simply because the Army has a mobile 5kw generator that makes 150 cu.ft/hr I’m guessing this would generate1500 cu.ft./hr. But you could upscale everything and/or use parallel units to increase power. I don’t know how cost effective it would be but it is free energy.
I’m not sure how to manage the power surges which would look like the top half of a sine wave. Probably capacitor and/or battery banks instead of a flywheel.
A tall tower with a weight might not be the way to go either.(100ft. tower?) You might have to wind up the belt with a motor (more losses).
I not sure how to handle swells over the design capacity or ocean currents and storms.
I don’t know if you can put 8 ton anchors in the sea floor.
Maybe you wouldn’t need tide adjustment currents will pull it away from the anchor and keep them tight.