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[Psion5]

Morning, fellow DF enthusiasts!

I'm currently working on a megaproject that has a few very specific requirements. Specifically, I need to find an embark site where the ocean freezes for a short time each year (2 weeks to a month). I know that I can get some general temperature info from the embark site selection screen (warm, temperate, cold, etc), but based on at least 20 sites I've looked at there is a lot of variation within these very general temperature ranges. I've had temperate sites where the ocean stays frozen 6 months, and others where the ocean never freezes. Since I'm not a fan of constantly guessing, or starting a fort and then surviving until winter just to see if the site is worthwhile, I'd like to obtain some more precise information about how seasonal temperature changes work. My questions:

1. Is there any way, in Fortress Mode, to determine the current "ambient temperature" - IE the temperature that controls whether the oceans freeze or not

2. Is it currently known exactly how much temperature varies by season?

3. Is the seasonal temperature variation dependent on the min/max used in worldgen or does worldgen just set the "average" temperature that is modified by the seasons?

Thanks in advance for your assistance! I'm not above using tools to find this temperature information, though I have no interest in modifying the world post-generation to control the temperature.

[i2amroy]

Generally the biggest variation in temperature is in the "temperate" region. For reference purposes:
Freezing - frozen year round
Cold - unfreezes at least temporarily, might be only a few days
Temperate - Ranges from being unfrozen almost all year to being frozen most of the year, at 2/3rd's is usually when it moves to Cold/Warm
Warm - Doesn't freeze except extremely rarely. Water doesn't evaporate except extremely rarely
Hot - Water evaporates during the summer months
Scorching - Water evaporates year round and almost immediately.

So if you embark on a "Warm" or hotter climate then nothing should ever freeze. Anything colder then that should freeze, at least temporarily during the course of the year. For your purposes it sounds like what you want to do is find a "Warm" climate, and then move towards the cold edge until you hit "Temperate" and stop there. That should get you a biome that only freezes for a small amount of time.

As for exact answers:
1)DFHack can give you the temperature of a given tile at any given point in time, but it can't determine how it will vary with the seasons. So no, there isn't anything that can do this.
2)It varies AFAIK. Some places will have greater variance then others.
3)I believe world generation just handles averages up until you actually embark, at which point it looks at the saved climate data to handle the exact specifics.

Just as a question, but what exactly are you building? I can't think of any megaprojects off of the top of my head that absolutely require freezing (i.e. that whatever it needs it for can't be done in some other method).

[Psion5]

To put it simply, I'm building a fortress under the ocean. This requires that I first wall off part of the ocean and then pump the water out. While this project does not strictly require a freezing ocean, it's significantly easier than the next best method, which involves creating a massive obsidian wall above the sea via bridges and then dropping it into the ocean (in addition, that makes it difficult impossible to remove all but the top level of the sea wall, which is not at all aesthetically pleasing).

I actually had a map where this previously but I lost it when my save got corrupted. I've got seasonal backups turns on now.

If DFHack can give me temperature info, I may try performing some tests to see how temperature changes due to seasons, weather, etc.

[Urist Da Vinci]

To put it simply, I'm building a fortress under the ocean. This requires that I first wall off part of the ocean and then pump the water out. While this project does not strictly require a freezing ocean, it's significantly easier than the next best method, which involves creating a massive obsidian wall above the sea via bridges and then dropping it into the ocean (in addition, that makes it difficult impossible to remove all but the top level of the sea wall, which is not at all aesthetically pleasing).

I actually had a map where this previously but I lost it when my save got corrupted. I've got seasonal backups turns on now.

If DFHack can give me temperature info, I may try performing some tests to see how temperature changes due to seasons, weather, etc.

You can also collapse the sea wall into the ocean floor, as long as the seafloor-cavern distance is greater than the height of your sea wall, leaving a pleasing flat ocean floor.

[cerevox]

You could generate a new world with the advanced world builder and narrow the possible temperature ranges and set the mid point such that you get the desired result. The whole world would end up very samey, but if you are looking for a specific temperature ocean that might be your best bet.

[wierd]

A freezing ocean mostly negates the benefits of living beneath the ocean, at least concerning sieges.

I personally think that dwarves need to invent volcanic ash concrete. The ancient romans had it in 10AD. I think that qualifies as being within the limits toady set for anachronism.

(Volcanic ash based concrete differs from portland cement, because volcanic ash based concrete can set underwater. This would make it invaluable for sealing aquifer breaches, and for aquatic fortress construction. )

But such a request belongs on the DF suggestions forum. *sigh*

The best we have is magma, with all its foibles.

Perhaps you could make use of screwpumps to part the red sea, moses style?  Just build a series of constructed floor ducts, windmills, and waterways. Pump the ocean up and off the map up high, faster than the flow moves in from the sides.  This should give you empty space to build walls down into. Build your access chimney, and when all done, kill the support holding up the pump architecture.  It collapses into rubble, since it is a construction, hopefully leaving your access chimney intact.  THEN construct the fortress.

[vanatteveldt]

I think this thread contains some great examples of how to master the ocean without freezing or magma:

http://www.bay12forums.com/smf/index.php?topic=75780.0

[i2amroy]

Personally the way that I would do it without freezing is to use minecarts to haul globs of magma up to the surface. From there you can use them to drip magma onto the ocean, forming obsidian that instantly solidifies and drops down to the bottom of the ocean. By repeating this method you could build walls that reached all of the way up from the ocean floor to the surface of the ocean. Then when you are done you would collapse those obsidian walls down into the ocean bed with cave-ins (though you might need to collapse a series of tiles outside of your wall in order to remove the support on the outside edge of your wall, sort of a double ring, where the inner one is your ocean wall). The end result should be a perfectly flat ocean floor or a slight trench in the ocean floor.

[Psion5]

I think this thread contains some great examples of how to master the ocean without freezing or magma:

http://www.bay12forums.com/smf/index.php?topic=75780.0

Interesting - this is the first time I've heard of the technique using bridges and ramps to breach the bottom of a body of water, but I sure how it works. From the wiki:

Dig out ramps leading up to the first level below an ocean. Build a retracting bridge on that level, directly over the ramps (be sure to leave them in place!) and link it to a trigger. Carefully seal off the chamber to make it water tight. Now with the bridge in place, designate ramps up to the ocean adjacent to the bridge. Diggers with access to the level below the bridge can dig those ramps up from the level of the bridge, allowing the ocean to fill the chamber; even with the ramp squares underwater they can still dig them out. And not a drop of water will touch them... provided they clear out before you pull the lever.

If I'm reading this correctly...

W = water
S = stone
_ = retractable bridge
E = dug out space

Code: [Select]

W W W W
S S S S
_ _ _ _
E E E EIf I designate the S level for upward ramps, dwarves on the E level can carve them without going to the same level as the retracted bridge. Do I have that correct?

[Hyndis]

A cold biome ocean should freeze during winter, however freezing and unfreezing things can be hazardous both to your dwarves as well as your FPS.

An easy way to handle it is to only turn temperature on when you want to play with things temperature related. This will also massively boost your FPS if temperature is off. Wait until the ocean freezes, then save and exit. Turn temperature off. You can then dig out the ocean as chunks of ice and construct walls or other tiles at your leisure. Once you're done, then turn temperature back on and wait for the ocean to thaw.

After the ocean is liquid, save and exit once more. Now turn temperature off. This will cause the ocean to remain liquid all year round, both improving your FPS as well as preventing dwarves from plummeting to their doom in the ocean if they're caught on melting ice.

Also it will prevent sieges and caravans from taking an impromptu swim. If they arrive on the ice, but the ice melt, they go for a swim.

I actually enjoy ocean embarks. I like embarking on a large 5x5 embark, but only the very corner tile is on land. The other tiles are all water. This means the only entrance to the map is on the very corner. The entrance can be further constricted by building drawbridges and raising them. This can be done at the edge of the map, and creatures can only spawn on a natural edge of the map tile.

I then station my military there in the corner on an open field. No traps, no tricks, just dwarven steel against the goblin hordes, for honor and glory.

[Psion5]

So last night I performed some experiments regarding a map edge drain, and while I am impressed I don't think that it'll be sufficient for my purposes. Based on my observations, each level of ocean bordering the map edge has a "pressure" of MIN(n/7, 7), so each tick water flows in from the map edge at that rate. While this isn't a problem for shallow bodies of water, attempting to drain an deep ocean seems to overwhelm the maximum flow rate of the even a ten tile wide drain, not to mention the fact that my framerate instantly and permanently drops to 1.

Unless I can find a temperature-based solution, I may have to go by to my original, even more dwarfy plan - drop a massive obsidian cast into the ocean, one level at a time, until I have a complete sea wall.

[Hyndis]

Try embarking in a cold ocean biome. Wait until it freezes, save and exit, then turn temperature off.

Do your stuff to the now frozen ocean. Then save and exit, and turn temperature back on.

[Psion5]

Try embarking in a cold ocean biome. Wait until it freezes, save and exit, then turn temperature off.

Do your stuff to the now frozen ocean. Then save and exit, and turn temperature back on.

I could, but to me it would feel like cheating. For the sake of my own pride I'm not going to rely on such techniques.

[Laserhead]

Not entirely correct on the bridge and ramp thing, you can't have that stone layer or they won't be able to reach. The water is held up by the floor of the water layer. You want the bridge directly below that, and the last up ramps (that actually tap the water) beside the bridge on the same level.

[Psion5]

Not entirely correct on the bridge and ramp thing, you can't have that stone layer or they won't be able to reach. The water is held up by the floor of the water layer. You want the bridge directly below that, and the last up ramps (that actually tap the water) beside the bridge on the same level.

Hmmm...but if the ramps tapping the water are next to the bridge horizontally, why doesn't the water immediately flow onto and over the bridge?