Silk Town-Thesmar Canal

isaac_newton wrote:

Keith_w wrote:Why would you need pumps? You need valves and pipes to allow water to flow from the upper level to the lower level in a controlled manner

SNIP
The long arm is called a balance beam. There is a really interesting article on Wikipedia about how locks work. https://en.wikipedia.org/wiki/Lock_(water_transport)#Gates

Yup - that is interesting. Here is the relevant bit about water usage/pumping

The main problem caused by locks is that, each time a lock goes through one fill-empty cycle, a lockful of water (tens of thousands up to millions of litres) is released to the lower pound. In more simplistic terms, on a canal where only one boat will fit into a lock, a boat travelling from the summit pound to the lowest pound is accompanied on its journey by one 'personal' lockful of water. A boat going the other way also transfers a lockful of water from the summit pound to the lowest pound. To prevent the canal from running dry, some method must be used to ensure that the water supply at the canal summit is constantly replenished at the rate that the water is being drained downwards. This is, of course much more of a problem on an artificial canal crossing a watershed than on a river navigation.
...
Pumping
Where it is clear that natural supply will not be sufficient to replenish the summit level at the rate that water will be used (or to allow for unexpected periods of drought) the designer may plan for water to be back-pumped back up to the summit from lower down. Such remedies may of course be installed later, when poor planning becomes apparent, or when there is an unforeseeable increase in traffic or dearth of rain. On a smaller scale, some local pumping may be required at particular points (water is continually recycled through some locks on the Kennet and Avon canal).

I think the operative word in that quote is "Where". Not all canals require them. I recall that is mentioned in at least one of the books that the water supply in the canal is replenished from a nearby river which probably requires pumping. I also notice that it refers to "crossing a watershed", which is a high point of land from either side of which the water flows in different directions. For example, the Rocky mountains are a watershed from which the water on the eastern side flows to Hudson's Bay, and the western side which flows to the Pacific Ocean. You would definitely need pumps to replenish the water supply in that case.

Easternmystic wrote:I'm sure that canal operators and builders everwhere are astounded that they have been doing it wrong for centuries!

The tank or tanks are normally empty and the lock gate is in the closed position. When the gate needs to be opened, water is allowed to flow into the tank which changes the weight as well as the weight distribution of the gate mechanism. the combination of the two forces the gate open. To close the gate, The water is pumped out of the tank.

Finally, canal gates are only opened when the water level on each side of a gate has been equalized. Equalizing the water levels, requires the use of valves and plumbing to raise or lower the water level in the lock before opening one of the gates. Trying to open a lock gate when the water levels sre unequal usually results in damage to the lock, tha lock gates and the vessel in the lock at the time. It's generally considered to be a bad thing to do.

How to fill or drain a lock:

A paddle – sometimes known as a slacker, clough, or (in American English) wicket – is the simple valve by which the lock chamber is filled or emptied. The paddle itself is a sliding wooden (or nowadays plastic) panel which when "lifted" (slid up) out of the way allows water to either enter the chamber from the upper pound or flow out to the lower pound. A gate paddle simply covers a hole in the lower part of a gate; a more sophisticated ground paddle blocks an underground culvert. There can be up to 8 paddles (two gate paddles and two ground paddles at both upper and lower ends of the chamber) but there will often be fewer. For a long period since the 1970s it was British Waterways policy not to provide gate paddles in replacement top gates if two ground paddles existed. The reason for this was given as safety, since it is possible for an ascending boat to be swamped by the water from a carelessly lifted gate paddle. However, without the gate paddles the locks are slower to operate and this has been blamed in some places for causing congestion. Since the late 1990s the preferred method has been to retain or re-install the gate paddles and fit 'baffles' across them to minimise the risk of inundation.

How to open or close a gate:

Balance beam

A balance beam is the long arm projecting from the landward side of the gate over the towpath. As well as providing leverage to open and close the heavy gate, the beam also balances the (non-floating) weight of the gate in its socket, and so allows the gate to swing more freely

Source for both quotes: https://en.wikipedia.org/wiki/Lock_(water_transport)#Gates

Keith_w wrote:I think the operative word in that quote is "Where". Not all canals require them. I recall that is mentioned in at least one of the books that the water supply in the canal is replenished from a nearby river which probably requires pumping. I also notice that it refers to "crossing a watershed", which is a high point of land from either side of which the water flows in different directions. For example, the Rocky mountains are a watershed from which the water on the eastern side flows to Hudson's Bay, and the western side which flows to the Pacific Ocean. You would definitely need pumps to replenish the water supply in that case.

Nobody in this thread said that all locks on Safehold require pumps. This discussion started when someone asked 'why would a lock ever need a pump?' That question has now been answered, by several people. And note, by the way, that this was asked in the context of the Salthar Canal, which goes from sea-level over a neck of land of unknown height back to sea-level. So it does cross a watershed, and that section of the article is quite applicable.

Keith_w wrote:...For example, the Rocky mountains are a watershed from which the water on the eastern side flows to Hudson's Bay, ...

Actually, the American Rocky Mountains drain eastward into the Mississippi and/or the Gulf of Mexico. That's also true for the southern portion of the Canadian Rockies, although I don't recall off-hand how far North that's still the case.

One, possibly minor, consideration on chain of locks v single large [high] lock...

The gates would almost certainly be of wood in Safehold, so that's likely to limit the lock size in itelf. I just can't imagine lock doors 100foot high. Especially if they leak like the ones in the UK do!

I imagine that going up or down a 100 foot high chamber with the water swirling round would be a deeply unpleasant experience!!

isaac_newton wrote:One, possibly minor, consideration on chain of locks v single large [high] lock...

The gates would almost certainly be of wood in Safehold, so that's likely to limit the lock size in itelf. I just can't imagine lock doors 100foot high. Especially if they leak like the ones in the UK do!

I imagine that going up or down a 100 foot high chamber with the water swirling round would be a deeply unpleasant experience!!

The pressure would also go up fast, causing those leaks to be pretty bad. At 100 feet, the pressure at the bottom would be around 44 pounds per square inch.

Hi SWM,

Except we have Rhobair explaining that his temporary gates are wood so they'll leak more than normal, implying the regular gates are metal or something else and will be replaced when all is ready.

This is interesting since Shan-wei built them, but only expected them to last around 500 years, not knowing what Langhorne was doing, so what did she build them out of?

While non-ferrous metal seems obvious, large aluminum manufacture on Safehold is impossible, or galvanized steel since the archangels didn't want any large industries [self-sufficient villages were their goal], but coating the exterior in lead or bronze [copper and tin etc] is possible, and certainly expensive enough that only the church could afford the whole world's annual maintenance costs.

However I wonder if she didn't use some advanced materials that she expected the colonists to be able to replace when the time came as they would then have had the same tech.

So could some gates have been made out of carbon fiber, concrete or 'ceramicrete' etc, that might be patched as necessary, or used in lieu of the lead or bronze outer water proof protection, with wood and rubber for the fender and gate contact seals?

Granted, the gates blown up in the GCR weren't venerated like they were a thousand years old made by the archangels, so I expect they weren't, but then what is the replacement rate?

If they were expected to last only 500 and have now gone almost a thousand, there is probably a huge massive failure point coming especially if they're not rust proof, and I'd expect the last archangels to have warned the temple to prepare for it years if not decades in advance, but can the CoGA now afford it when they're almost bankrupt?

Perhaps only the EoC will now be able to afford replacing the lock gates when they fail, another reason to accept the end of the jihad and trade with them, otherwise the national economy might collapse.

L

SWM wrote:

isaac_newton wrote:One, possibly minor, consideration on chain of locks v single large [high] lock...

The gates would almost certainly be of wood in Safehold, so that's likely to limit the lock size in itelf. I just can't imagine lock doors 100foot high. Especially if they leak like the ones in the UK do!

I imagine that going up or down a 100 foot high chamber with the water swirling round would be a deeply unpleasant experience!!

The pressure would also go up fast, causing those leaks to be pretty bad. At 100 feet, the pressure at the bottom would be around 44 pounds per square inch.

lyonheart wrote:Hi SWM,

Except we have Rhobair explaining that his temporary gates are wood so they'll leak more than normal, implying the regular gates are metal or something else and will be replaced when all is ready.

This is interesting since Shan-wei built them, but only expected them to last around 500 years, not knowing what Langhorne was doing, so what did she build them out of?

I expect that they were made out of reinforced wood, rather than all-wood. Perhaps wood with metal sheeting. I seriously doubt that the lock gates are made of all metal. And I doubt that Shan-wei expected them to last even 500 years. I expect that they were intended to be replaced when necessary. They would not have been made of materials that Safehold could not replace.

lyonheart wrote:Hi SWM,

Except we have Rhobair explaining that his temporary gates are wood so they'll leak more than normal, implying the regular gates are metal or something else and will be replaced when all is ready.

This is interesting since Shan-wei built them, but only expected them to last around 500 years, not knowing what Langhorne was doing, so what did she build them out of?

While non-ferrous metal seems obvious, large aluminum manufacture on Safehold is impossible, or galvanized steel since the archangels didn't want any large industries [self-sufficient villages were their goal], but coating the exterior in lead or bronze [copper and tin etc] is possible, and certainly expensive enough that only the church could afford the whole world's annual maintenance costs.

However I wonder if she didn't use some advanced materials that she expected the colonists to be able to replace when the time came as they would then have had the same tech.

So could some gates have been made out of carbon fiber, concrete or 'ceramicrete' etc, that might be patched as necessary, or used in lieu of the lead or bronze outer water proof protection, with wood and rubber for the fender and gate contact seals?

Granted, the gates blown up in the GCR weren't venerated like they were a thousand years old made by the archangels, so I expect they weren't, but then what is the replacement rate?

If they were expected to last only 500 and have now gone almost a thousand, there is probably a huge massive failure point coming especially if they're not rust proof, and I'd expect the last archangels to have warned the temple to prepare for it years if not decades in advance, but can the CoGA now afford it when they're almost bankrupt?

Perhaps only the EoC will now be able to afford replacing the lock gates when they fail, another reason to accept the end of the jihad and trade with them, otherwise the national economy might collapse.

L

Hi Lyonheart,

I've been wondering about this myself. The locks on the canals that the Archangels built might have been made out of TF materials. But a goodly percentage by this time would have been built by Safeholdens without access to TF materiaals...

Out of what? I could imagine stone and mortar for the walls of the gates with the framing for the gates themselves along with the gates being made out of iron....

That would introduce a lot of corrosion, though. I would imagine that they would be subject to frequent maintainence and replacement...

Don

n7axw wrote:SNIP

Hi Lyonheart,

I've been wondering about this myself. The locks on the canals that the Archangels built might have been made out of TF materials. But a goodly percentage by this time would have been built by Safeholdens without access to TF materiaals...

Out of what? I could imagine stone and mortar for the walls of the gates with the framing for the gates themselves along with the gates being made out of iron....

That would introduce a lot of corrosion, though. I would imagine that they would be subject to frequent maintainence and replacement...

Don

Wasn't the munitions canalboat explosian in a lock on the Langhorne. If that was Terran tech, then would it have caused much damage at all? Or did you mean originally?