Silk Town-Thesmar Canal

SWM wrote:

Keith_w wrote: quote="SWM"
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. /quote

You are right, the question was answered, mostly by me. Why are you so concerned about this discussion? It's not like we have a new snippet to read, enjoy and discuss.

Huh?

I don't read snippets or spoilers. I have no idea whether there are new snippets to discuss.

And I am concerned with the discussion because I have been a part of the discussion from the beginning. In fact, you were responding to me back when you asked the question "why would you need pumps?", which started this whole subtopic. So I'm confused why you think I should not be part of the discussion.

That's certainly your choice, and one which others do not make.

As for the query about the concern about the discussion, Just as you seem to have misinterpreted my statement to imply that you should not be part of the discussion - after all this is a forum, not a private conversation - I felt that you were trying to cut off further discussion about pumps on canals, even though the question had been discussed and answered. If I was wrong in that belief, then I apologize.

Edited 2x to clean up quoting.

n7axw wrote:
Do we have any idea how Safehold pumps are powered?

Don

Sorry to resurrect an old thread that had finally died down after much backing and forthing, but I have just been rereading the series and during the GCR and then during the canal repairs in the next book there are so many mentions of pumps as a part of the lock. In fact, they seem to be critical parts to the lock. I can imagine a modern lock having a diesel or electric motor driving the pump to push the water back up to the upper level when the lock is emptying down to the lower level to minimize water loss so it would be critical to lock function. I can also imagine a much smaller pump that would run continuously to take water out of the lower canal and pump it back into the upper canal to also slow down water usage from the upper canal, but this would not be critical to lock usage.

For Safehold, the question of what powers the pumps is very interesting. Using the blessed three of wind, water, and muscle we have many problems. The volume of water needed to raise or lower a 140' long, 40' wide barge up even just a 10 foot rise is huge. It would take many windmills to pump that much water back up to the upper canal and they would run constantly and thus not be critical to lock function. It would take several water wheels wasting a great deal more water than they are pumping back up but could conceivably be used for a VERY slow emptying of the lock to go downhill. And I shudder to think of how many men (or even just horses, dragons, etc) it would take to crank the pumps to move that much water back uphill for each cycling of the lock.

When a canal connects a lake or river at the high end with anything else lower down then there should be a plentiful supply of water to allow using one full charge of water each time the lock is used. If the locks are needed to go over and back down a terrain feature like a ridgeline with no source of water at the top then I can see catch basins and lots of windmills feeding a small lake or reservoir at the top, but even then they would not be part of the lock and not critical to short term use. With the limitations of the Proscriptions, I can't see any other way to operate a lock except pipes and valves to fill the lock from the upper level and empty the lock into the lower level.

So what does power the pumps? Engineers with enquiring minds want to know :)

rocket_scientist wrote:

n7axw wrote:
Do we have any idea how Safehold pumps are powered?

Don

Sorry to resurrect an old thread that had finally died down after much backing and forthing, but I have just been rereading the series and during the GCR and then during the canal repairs in the next book there are so many mentions of pumps as a part of the lock. In fact, they seem to be critical parts to the lock. I can imagine a modern lock having a diesel or electric motor driving the pump to push the water back up to the upper level when the lock is emptying down to the lower level to minimize water loss so it would be critical to lock function. I can also imagine a much smaller pump that would run continuously to take water out of the lower canal and pump it back into the upper canal to also slow down water usage from the upper canal, but this would not be critical to lock usage.

For Safehold, the question of what powers the pumps is very interesting. Using the blessed three of wind, water, and muscle we have many problems. The volume of water needed to raise or lower a 140' long, 40' wide barge up even just a 10 foot rise is huge. It would take many windmills to pump that much water back up to the upper canal and they would run constantly and thus not be critical to lock function. It would take several water wheels wasting a great deal more water than they are pumping back up but could conceivably be used for a VERY slow emptying of the lock to go downhill. And I shudder to think of how many men (or even just horses, dragons, etc) it would take to crank the pumps to move that much water back uphill for each cycling of the lock.

When a canal connects a lake or river at the high end with anything else lower down then there should be a plentiful supply of water to allow using one full charge of water each time the lock is used. If the locks are needed to go over and back down a terrain feature like a ridgeline with no source of water at the top then I can see catch basins and lots of windmills feeding a small lake or reservoir at the top, but even then they would not be part of the lock and not critical to short term use. With the limitations of the Proscriptions, I can't see any other way to operate a lock except pipes and valves to fill the lock from the upper level and empty the lock into the lower level.

So what does power the pumps? Engineers with enquiring minds want to know

Hmmm.

Your logic is generally correct, but I can think of a case where you don't need ANY pumps to make the lock work. You need two valves.

Picture this...

The lock is between a higher canal and a lower one. If the valve is in a pipe between the lock and the lower side canal, then when the lock closes, you can just open the low-side valve and drain the lock to the level of the low-side canal. Bigger pipe and bigger valve --> faster operation.

That accounts for LOWERING the vessel.

To RAISE the vessel, you need one special case: a large body of water that's HIGHER than the canal at the high side of the lock. Vessel on the lower lock enters the lock and the door closes. Valve from the body of water that's at or higher than the level of the high-side is opened. Water flows into the lock. If the body of water is at exactly the level of the high-side canal, then you can just leave it open until the lock level and the canal level are equal. If the body of water is higher than the canal's high side, then you'll have to shut the valve at the right time to keep from raising the lock level too high.

But you're right, large-volume pumps and a reservoir of water make it all easier. IIRC, the Mad Wizard told us in LaMA that the locks fill in about 15 minutes. For the 140'X40' LOCK, that would be 56,000 cubic feet of water for a 10' lift, or about 3,733 cubic feet (roughly 28,000 gallons) of water PER MINUTE.

LOTTA WATER!

EDIT...

Just on a whim, I looked at some commercial pump curves. For the 48" model I was looking at, with a 175 RPM pump and low dynamic head, you could get as much as 32,000 GPM flow rate. Of course a Safehold pump wouldn't be as efficient due to propeller/casing tolerances and leakage. But maybe with multiple pumps?

Ummm...

I'm not sure if you realise it, but your 'special case' is a description of the normal operation of a locked canal system - there's _always_ a large body of water higher than the upper level of the lock: the upstream section of the canal, together with the watershed that provides the operating water. If there isn't, that canal doesn't stay in operation very darned long. A fate that met more than one canal project in England in the glory days of canal building, AAMOF, when they were built across areas that didn't have enough precipitation over the year to supply the locks on one side or the other of the height of land, and nowhere to divert it from. [believe it or not, there actually are places in Soggy Olde England where that can happen].

The only time you are even going to see a pumped canal system is if you _absolutely_ have to route it across an area like that, and none of the alternatives, such as a marine railway [which does _not_ require steam power to operate] have ever crossed the minds of the engineers building it, and the economics are irrelevant. A situation that doesn't, as far as I can see, obtain in northwestern Siddarmark - the volume of water flowing through the damage locks in the one scene we are shown makes it clear that there's no need to do it there, and I don't see any other place on the maps where it seems at all likely. For that matter, I'm not aware of any place it was ever done on Earth, either.

WeberFan wrote:

rocket_scientist wrote:Sorry to resurrect an old thread that had finally died down after much backing and forthing, but I have just been rereading the series and during the GCR and then during the canal repairs in the next book there are so many mentions of pumps as a part of the lock. In fact, they seem to be critical parts to the lock. I can imagine a modern lock having a diesel or electric motor driving the pump to push the water back up to the upper level when the lock is emptying down to the lower level to minimize water loss so it would be critical to lock function. I can also imagine a much smaller pump that would run continuously to take water out of the lower canal and pump it back into the upper canal to also slow down water usage from the upper canal, but this would not be critical to lock usage.

For Safehold, the question of what powers the pumps is very interesting. Using the blessed three of wind, water, and muscle we have many problems. The volume of water needed to raise or lower a 140' long, 40' wide barge up even just a 10 foot rise is huge. It would take many windmills to pump that much water back up to the upper canal and they would run constantly and thus not be critical to lock function. It would take several water wheels wasting a great deal more water than they are pumping back up but could conceivably be used for a VERY slow emptying of the lock to go downhill. And I shudder to think of how many men (or even just horses, dragons, etc) it would take to crank the pumps to move that much water back uphill for each cycling of the lock.

When a canal connects a lake or river at the high end with anything else lower down then there should be a plentiful supply of water to allow using one full charge of water each time the lock is used. If the locks are needed to go over and back down a terrain feature like a ridgeline with no source of water at the top then I can see catch basins and lots of windmills feeding a small lake or reservoir at the top, but even then they would not be part of the lock and not critical to short term use. With the limitations of the Proscriptions, I can't see any other way to operate a lock except pipes and valves to fill the lock from the upper level and empty the lock into the lower level.

So what does power the pumps? Engineers with enquiring minds want to know

Hmmm.

Your logic is generally correct, but I can think of a case where you don't need ANY pumps to make the lock work. You need two valves.

Picture this...

The lock is between a higher canal and a lower one. If the valve is in a pipe between the lock and the lower side canal, then when the lock closes, you can just open the low-side valve and drain the lock to the level of the low-side canal. Bigger pipe and bigger valve --> faster operation.

That accounts for LOWERING the vessel.

To RAISE the vessel, you need one special case: a large body of water that's HIGHER than the canal at the high side of the lock. Vessel on the lower lock enters the lock and the door closes. Valve from the body of water that's at or higher than the level of the high-side is opened. Water flows into the lock. If the body of water is at exactly the level of the high-side canal, then you can just leave it open until the lock level and the canal level are equal. If the body of water is higher than the canal's high side, then you'll have to shut the valve at the right time to keep from raising the lock level too high.

But you're right, large-volume pumps and a reservoir of water make it all easier. IIRC, the Mad Wizard told us in LaMA that the locks fill in about 15 minutes. For the 140'X40' LOCK, that would be 56,000 cubic feet of water for a 10' lift, or about 3,733 cubic feet (roughly 28,000 gallons) of water PER MINUTE.

LOTTA WATER!

EDIT...

Just on a whim, I looked at some commercial pump curves. For the 48" model I was looking at, with a 175 RPM pump and low dynamic head, you could get as much as 32,000 GPM flow rate. Of course a Safehold pump wouldn't be as efficient due to propeller/casing tolerances and leakage. But maybe with multiple pumps?

To take this discussion in another Direction I wonder if Siddarmark would be willing to go to war over the Canal as it seems that they'll default and lose access to any income from the canal whatsoever,as I'd assume even they'd realize they'd going to war with multiple nations at once would result in very bad things happening for them?

Well, a lot would depend on their reasons - as distinct from their _pretext_ - for going to war. Assumptions about potential allies would also matter. Or co-belligerents, at any rate, able to provide serious distractions and keep their opponents from concentrating against them.

Don't forget, though, that they don't have the examples of Hitler or Napoleon in front of them. In fact, their only historical example of a one vs. many conflict is probably Charis. They may well _not_ realise immediately that that's not a particularly relevant precedent even without all the still-hidden machinations that lead to the Jihad collapsing.

Michae wrote:To take this discussion in another Direction I wonder if Siddarmark would be willing to go to war over the Canal as it seems that they'll default and lose access to any income from the canal whatsoever,as I'd assume even they'd realize they'd going to war with multiple nations at once would result in very bad things happening for them?

Isilith wrote:The two of you keep bringing up Desnairs shipbuilding capability as proof that Desnair SHOULD have had a navy. Totally ignoring the textev that states that shipbuilding capability was built up by the church AFTER the Armageddon Reef disaster, so that they could build a new NoG to fight Charis.

And ignoring the fact that Desnair, despite an incredible coastline, had no interest in being a maritime power. Their great nobles derived their wealth from ownership of land, not seagoing trade, and their territorial ambitions were focused on land as well. Beyond a basic coastal defense force (which was what galleys were designed to be - they weren't designed for blue water sailing, which is why merchants all used galleons - the Emperor and the great nobles saw no need for a navy and had no reason to build one.

This changed when Mother Church declared Jihad and started shoveling marks at Desnair to build a navy after Charis defeated the combined navies of Chisholm, Corisande, Dohlor, Emerald and Tarot in the battles detailed in OAR and Mother Church needed replacements fast, but it took that to get Desnair into the navy game.
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Dennis