Talk:Tide mill

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This definition so far only details mills that were powered by the falling tide. Is it posisble to power a tide mill by both the rise and the fall? Logic says "yes" if the mill pond principle is used in both directions (the sea is the pond for the rise), but potentially for a shorter period on the rise. Are there any examples, ancient or modern? Fiddle Faddle 09:30, 1 May 2006 (UTC)

Reversing tidal power plant - see the Rance article. Technically, in hindsight, it would have been reasonably simple - but none of the historical examples I am aware of show this capability, this is what the article states also.Bridesmill 14:50, 1 May 2006 (UTC)

Tks, noticed it. It was hiding in plain sight! With the older mills it may have been a "direction of rotation" issue. Perhaps a reversing gearbox or a twin race system with decoupled wheels were too complex, or too expensive. Fiddle Faddle 16:01, 1 May 2006 (UTC)

I think its more to do with having a consistent supply and being able to control the amount of water used Oxyman42 22:10, 11 June 2006 (UTC)

I am the miller at Eling Tide Mill, the only fully working and productive tide mill left in the UK, and run the mill every day. The article is incorrect, and I'm just contemplating editing it. The Mill only runs on the outflow from the pond, but it is incorrect to say it works on the ebb tide. The main limitation on milling is simply the tide height: the tide must be below the bottom of the waterwheel for the Mill to run efficiently - if the tide is on the wheel at all, there is too much drag for the wheel to run fast enough to produce flour in any quantity or of a good quality.

The actual running cycle is as follows:

(1) One-and-a-half hours after second high water (as we experience the double high water feature of the central section of the English channel) the ebbing tide reaches the axle of the wheel, and if I open the sluice the wheel will turn very slowly. We do this as a demonstration to vistors in the Mill at this time, but it wouldn't have been done in the old days as productively it is useless and just wastes water.

(2) Over the next hour the ebbing tide falls down the lower half of the wheel, the wheel continues running slowly, speeding up gradually as the drag decreases, but in fact I have to keep slowing it down as while the drive comes on in pulses as the blades ('buckets') pass in front of the jet of water from the sluice the drag is continuous, which creates a 'banging' on the wheel which, if allowed to persist with force could rip the waterwheel from the axle.

(3) Two-and-a-half hours after second high water, the ebbing tide falls clear of the lower blades and I can open the mill up and let it run freely.

(4) Over the next 5 hours the Mill will operate freely. For the first part of this time the tide is ebbing to low water. For the second part - which, given the tidal curve in the Solent and the Young Flood Stand feature, is actually the majority of our running time - the tide is flooding but is still below the bottom blades of the waterwheel. This is the important factor for running - the tide must be below the wheel, Which way it's going doesn't matter.

(5) At the end of the five hours, about two-and-a-half hours before the next first high water, the rising tide begins to cover and interfere with the bottom blades. The drag slows the Mill past the point of useful operation, and in the old days at this point milling would have ceased for that cycle of the tide.

(6) Over the next hour, the flooding tide rises towards the level of the axle. As with the ebbing tide in (2) above, we can still keep running (in the same direction, with the drive coming from the water in the pond), but only slowly, not productively, and only do it as a heritage site/visitor attraction. this would not have been done in the old days.

(7) Once the flooding tide reaches the axle, the waterwheel comes to a halt, and no more running is possible as the tide continues flooding to first high water, oscillates between first and second high water, and ebbs for the first hour-and-a-half after second high water. We are then back to (1) above, and the cycle repeats.

We can therefore mill properly for 5 hours spaced around low water out of each 12 1/2 hour tide cycle, with an extra hour of slow demonstration turning on either side. The waterwheel turns in the same direction on the outflow from the millpond throughout.

Running in the opposite direction is not feasible for a number of reasons. The waterwheel is only designed to work in one direction, and the stones only go in one direction with no capacity for reversing the gearing linkages. Most importantly, though, the time during which the tide is higher than the level in the millpond is both very short - about half-an-hour - and the waterwheel is almost completely underwater during that time. As above, the waterwheel won't work even partially underwater, let alone completely.

At least once, back in the 18th century IIRC, someone designed a tide mill that would work both ways, involving two dams, one on either side of the mill, and a complex system of channels and gates to create a millrace area on both sides. It was far too expensive and complex, and was never built. If one wants to extend capacity, it is far easier just to add another wheel alongside the existing one to increase production during the milling phase of the cycle.

Modern examples of tidal barrage technology (as opposed to tidal stream) like the Rance have the advantage of using turbines. They essentially work the same way we do, but can work through a larger part of the cycle as they are not affected by the drag of the tide, just being limited by the requriement for a sufficient head.—The preceding unsigned comment was added by 15:17, 13 July 2006 DavidGb3 (talk • contribs).

Please feel free (but please sign your comments with four tildes (~~~~) which allopws us to keep track of who is saying what in discussions. I'd be most interested in the example of a 2-way tide mill - if you want to mention that in the article though, it will need citation. Feel free to jump in and edit; if you are not conversant with specific details of formating etc, don't worry, someone (here, likely me) will be along to fix it in accordance with the wiki manual of style (WP:MOS) - but don't bother memorizing that tome before jumping in Welcome aboard from a fellow miller (sort of - I live in an old converted watermill) Bridesmill 20:35, 13 July 2006 (UTC)

• Wholly in favour of an7y and all improvements to the article. Iyt strikes me that the screed above could be an excellent place to start. In all things here be bold and make edits. Obviously rememebr that others will edit your edits etc, etc. As an early contributor to the article I did the best I could with the resources I could find. Finding a live m,iller from Eling Mill to add to it is a major bonus. Welcome. Fiddle Faddle 20:49, 13 July 2006 (UTC)

Sorry about the lack of signature - didn't quite understand that bit until after I'd posted the edit. I'll give an edit to the article some thought (along with the Eling Tide Mill entry). Thanks for the welcome. --DavidGb3 21:09, 13 July 2006 (UTC)