Topic Actions

Topic Search

Who is online

Users browsing this forum: No registered users and 10 guests

Blowing the locks

This fascinating series is a combination of historical seafaring, swashbuckling adventure, and high technological science-fiction. Join us in a discussion!
Blowing the locks
Post by n7axw   » Tue Jun 02, 2015 7:37 pm

n7axw
Fleet Admiral

Posts: 5997
Joined: Wed Jan 22, 2014 8:54 pm
Location: Viborg, SD

We seemed to have reached a bit of a lull here on the Safehold forum and need some new threads to hash. So I am going to post this to see if anybody else has a better visualization of it than I do.

I reread that bit on the Great Canal raid in MTAT. The ironclads were blowing locks as they progressed down the canal to put the canal out of service. What bugs me about it a bit is how they managed that without trapping themselves. The only thing I could come up with was that they started on the uphill side of the canal which would mean that when each lock was blown, the ironclad would be headed downhill with the water growing progressively deeper with each lock blown until they reached the river, the sea or whatever which would mean that the last lock to be blown would actually drain the canal...

Does this make any sense or am I mixed up?

Don
When any group seeks political power in God's name, both religion and politics are instantly corrupted.
Top
Re: Blowing the locks
Post by Tonto Silerheels   » Tue Jun 02, 2015 9:28 pm

Tonto Silerheels
Captain of the List

Posts: 454
Joined: Wed Oct 12, 2011 6:01 pm

n7axw wrote:

Does this make any sense or am I mixed up?

Oh, yes. Definitely, without a doubt you're mixed up. Fortunately for me, you're mixed up in the same manner as I am, so let me tell you my thoughts.

The first location that we have to worry about is Fairkyn. Now, it's possible on the outside that Fairkyn is lower elevation than the Ice Ash River. It's not very probable, because if it were then there should be some kind of lake near Fairkyn that would drain the surrounding landscape. So, let's assume that Fairkyn is higher elevation than the Ice Ash. If that's the case then there are probably two gates on the Guarnak-Ice Ash canal that allow passage to the Ice Ash River. Let's call them the East-bound gate and the West-bound gate. If Charis had blown either of these gates then the Guarnak-Ice Ash canal would have drained into the Ice Ash or the area surrounding Fairkyn, stranding the task force. Therefore, neither of these gates could have been destroyed. However, at this location there were two other gates that allowed the raising and lowering of the vessels travelling on the canal. Once all of Charis's vessels had moved to the Ice Ash River, both of those gates could be destroyed.

The rule of thumb is that if you move to a higher elevation then you can't destroy anything you're on, but you can destroy everything else.

Now, just for the sake of ease of explanation, let's assume that the Guarnak-Sylmahn canal is at a lower elevation than the Hildermoss River. If it's not, then the explanation applies to the junction between the Guarnak-Sylmahn canal and the Hildermoss river.

Once Charis moves to the Guarnak-Sylmahn canal, then they can destroy all of the gates behind them. It will have the effect of draining the Guarnak-Ice Ash canal, but that's no concern of Charis, or possibly an advantage. In fact, it explains the fact that Wyrsham sees the drained canals in Guarnak. Either that, or the destruction of the Hildermoss gates.

So, the rule of thumb is that if you move to a higher elevation, destroy everything but the gates on the canal you're on. If you move to a lower elevation, destroy everything you see.

~Tonto
Top
Re: Blowing the locks
Post by JRM   » Tue Jun 02, 2015 11:21 pm

JRM
Lieutenant (Senior Grade)

Posts: 88
Joined: Sat Oct 26, 2013 2:47 am
Location: Honolulu, Hawaii

n7axw wrote:We seemed to have reached a bit of a lull here on the Safehold forum and need some new threads to hash. So I am going to post this to see if anybody else has a better visualization of it than I do.

I reread that bit on the Great Canal raid in MTAT. The ironclads were blowing locks as they progressed down the canal to put the canal out of service. What bugs me about it a bit is how they managed that without trapping themselves. The only thing I could come up with was that they started on the uphill side of the canal which would mean that when each lock was blown, the ironclad would be headed downhill with the water growing progressively deeper with each lock blown until they reached the river, the sea or whatever which would mean that the last lock to be blown would actually drain the canal...

Does this make any sense or am I mixed up?

Don


Hi Don,

I thought about the canals when we were speculating on BGV's campaign plan. I concluded that he would use his current 28,000 troops to clear the Northland Gap, the Guarnack Gap, and then have them secure the New Northland canal. Meanwhile he would bring his remaining forces to Guarnack to attack Wyrsham. I had in mind securing a logistical route for when BGV advances to the Hildermoss. I later read that the canal raid had destroyed the critical locks to the New Northland canal from the Hildermoss. So, it looks like my speculations are 0 for 2. (I also thought that Ahlverez would turn north for Evrytyn rather than Alykberg) Here is what I said about the canals.
Consider types of canals:

There are rivers where canal locks use diverted water to raise and lower boats at portage points. Destroying the locks doesn’t affect the navigability of either the upriver or downriver section of the river. It just stops navigation through the portage points. This was that case of the Hildermoss, and why after COGA repairs the locks between East Wing Lake and the Hildermoss, that navigation can only go up the Hildermoss as far as Ayaltyn.

There are canals that are channelized rivers. Here the constant flow of water is sufficient that destroying downstream locks does not affect navigation upstream. The Guarnack-Ice Ash Canal appears to be one of these, because Captain Bahrns destroyed downstream locks after he passed them without disrupting his progress.

There are canals that are effectively large aqueducts. The flow of water is not sufficient for navigation unless the downstream locks slow down the flow. The Guarnack-Sylmahn Canal is one of these. Here Captain Bahrns destroyed the upstream locks and was able to proceed. Destroying the downstream locks not only blocked the portage point, but disrupted navigation all of the way back to Guarnack.


LAMA August II Page 83:
“We should at least be able to move supplies by sled once the canals do freeze over,” Maigwair said hopefully, but Duchairn shook his head again.
“That’s going to be true to some extent, Allayn, but we’ve got too many stretches of canal bed— and over seventy miles of aqueduct— which’re basically dry now. I’m not sure there’s going to be enough standing water in them to provide the kind of ice we usually see in the winter, and without the locks and the pumps, we can’t get the water into them, either.


LAMA October VI Page 319
Tarikah’s coal traditionally came from Glacierheart and the Ice Ash Mountains via the New Northland Canal and the Guarnak-Ice Ash Canal, both of which had suffered significant damage from the Sword of Schueler during the Rising. When they’d been put back into operation , they’d been needed to supply Wyrshym’s own advance; and then the heretics had smashed the entire Guarnak -Ice Ash and the critical western locks of the New Northland.


James
Top
Re: Blowing the locks
Post by isaac_newton   » Wed Jun 03, 2015 3:26 am

isaac_newton
Rear Admiral

Posts: 1182
Joined: Fri Oct 18, 2013 6:37 am
Location: Brighton, UK

n7axw wrote:We seemed to have reached a bit of a lull here on the Safehold forum and need some new threads to hash. So I am going to post this to see if anybody else has a better visualization of it than I do.

I reread that bit on the Great Canal raid in MTAT. The ironclads were blowing locks as they progressed down the canal to put the canal out of service. What bugs me about it a bit is how they managed that without trapping themselves. The only thing I could come up with was that they started on the uphill side of the canal which would mean that when each lock was blown, the ironclad would be headed downhill with the water growing progressively deeper with each lock blown until they reached the river, the sea or whatever which would mean that the last lock to be blown would actually drain the canal...

Does this make any sense or am I mixed up?

Don


Hi Don

That puzzled me, so I posted about a while back in the thread on 're:General Winter'

RFC posted back with a detailed description of the process :-)

viewtopic.php?f=7&t=6325&p=165288#p165288

Speaking of whom - my v best wishes to the esteemed celery chaser!
Top
Re: Blowing the locks
Post by n7axw   » Wed Jun 03, 2015 7:56 am

n7axw
Fleet Admiral

Posts: 5997
Joined: Wed Jan 22, 2014 8:54 pm
Location: Viborg, SD

I went back and reread that thread where RFC posted his explanation.

You destroy the gates except the one between the ironclad and the demolition... or as Tonto observes, going downstream you can destroy everything...

That much makes sense. But then they leave one undestroyed gate in each set so the ironclad goes merrily on its way to the next set of locks in the system.

So you have one gate in each set untouched and the canal retains its waterlevel. That would mean one of two things. Either the canal is not rendered completely inoperable since the intact lock could be portaged around which would be as time consuming and as inconvenient as the dickens, but it could be done.

Or...

The ironclad makes a return trip and destroys the undamaged gate on its way downstream, riding the crest of the released water on its way.

I can see that I need to reread that section of MTAT again with maps in hand this time to firmly establish the ironclads routing in my head. I didn't remember any round trips...

Thanks to everybody who responded.

Don
When any group seeks political power in God's name, both religion and politics are instantly corrupted.
Top
Re: Blowing the locks
Post by isaac_newton   » Wed Jun 03, 2015 8:32 am

isaac_newton
Rear Admiral

Posts: 1182
Joined: Fri Oct 18, 2013 6:37 am
Location: Brighton, UK

n7axw wrote:I went back and reread that thread where RFC posted his explanation.

You destroy the gates except the one between the ironclad and the demolition... or as Tonto observes, going downstream you can destroy everything...

That much makes sense. But then they leave one undestroyed gate in each set so the ironclad goes merrily on its way to the next set of locks in the system.

So you have one gate in each set untouched and the canal retains its waterlevel. That would mean one of two things. Either the canal is not rendered completely inoperable since the intact lock could be portaged around which would be as time consuming and as inconvenient as the dickens, but it could be done.

Or...

The ironclad makes a return trip and destroys the undamaged gate on its way downstream, riding the crest of the released water on its way.

I can see that I need to reread that section of MTAT again with maps in hand this time to firmly establish the ironclads routing in my head. I didn't remember any round trips...

Thanks to everybody who responded.

Don


Definitely no round trip in the text - one way trip.

Dont forget that the locks are not just twin gates, but included pumps and associated stuff as well, and those were blown. Perhaps that enabled a slower 'drain down' than that happening if demolishing both [all] gates at once?
Top
Re: Blowing the locks
Post by Tonto Silerheels   » Wed Jun 03, 2015 9:14 am

Tonto Silerheels
Captain of the List

Posts: 454
Joined: Wed Oct 12, 2011 6:01 pm

isaac_newton wrote:

Definitely no round trip in the text - one way trip.

He may be referring to the short spur from the junction of the Guarnak-Ice Ash canal and Guarnak-Sylmahn canal to Guarnak. They made a round trip over that spur.

~Tonto
Top
Re: Blowing the locks
Post by n7axw   » Wed Jun 03, 2015 9:31 am

n7axw
Fleet Admiral

Posts: 5997
Joined: Wed Jan 22, 2014 8:54 pm
Location: Viborg, SD

Tonto Silerheels wrote:isaac_newton wrote:

Definitely no round trip in the text - one way trip.

He may be referring to the short spur from the junction of the Guarnak-Ice Ash canal and Guarnak-Sylmahn canal to Guarnak. They made a round trip over that spur.

~Tonto


Yeah, I remember that... Still, it is clear from textev that the canals, or large portions thereof did get drained. Isaac Newton's idea of how that might have happened does make sense.

Don
When any group seeks political power in God's name, both religion and politics are instantly corrupted.
Top
Re: Blowing the locks
Post by isaac_newton   » Wed Jun 03, 2015 9:45 am

isaac_newton
Rear Admiral

Posts: 1182
Joined: Fri Oct 18, 2013 6:37 am
Location: Brighton, UK

Tonto Silerheels wrote:isaac_newton wrote:

Definitely no round trip in the text - one way trip.

He may be referring to the short spur from the junction of the Guarnak-Ice Ash canal and Guarnak-Sylmahn canal to Guarnak. They made a round trip over that spur.

~Tonto


True, but they wouldn't have damaged any locks on the way to Guarnak!! :lol:

Maybe at that big 3 way junction, on the way out to Five Forks the raiders could do extra damage on the two arms that the they weren't using any more and on any cross connections between those two.

In fact I could see that allowing the water levels in the Guarnak branch to right down if it drained off to the Ice Ash branch [of course that depends on which is higher, but it is a possibility and that does explain Bishop N's observation on the canal bed visibility.
Top
Re: Blowing the locks
Post by Philip Stanley   » Wed Jun 03, 2015 11:01 am

Philip Stanley
Lieutenant Commander

Posts: 109
Joined: Sat Sep 29, 2012 10:20 am

I have another question regarding the lock system that might be introduced here:
To wit, what were the pumps for? I've read descriptions of canal locks and systems in the real world, in the USA, Britain, Panama, etc., and none of them used pumps. In all cases, the lock is filled and emptied by opening valves; filled by opening a valve to the upper water level, and emptied by opening a valve to the lower water level. In no case is any pump involved.
Can anyone explain RWC's reference to pumps?
Philip Stanley
Top

Return to Safehold