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Old 10-02-2010, 09:41 AM   #41
RogerBW
 
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Default Re: Seaplanes & Submarines

There's a big hazard with snorkelling (or even surface running) in rough weather with a diesel boat. You need fresh air in the crew spaces, so the usual arrangement has the air intake feeding into them, and the engine drawing air from the other end (human-exhaled air still having plenty of oxygen for diesel purposes). And this is all good.

Now the submarine hits some rough weather. You don't want water coming into the crew space, so the valve claps shut. The diesel keeps running, dropping the pressure in the crew space. Everyone's ears pop. Then they start to bleed. Then they die. (Unless someone was right there on the switches to kill the engine when this started.) This is called an engine run-on casualty, among other things.

A modern diesel boat has interlocks to kill the engine if the air intake is interrupted - though something like this may well have been what did for Great Wall 61 even so. A WWII-tech one doesn't.
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Old 10-02-2010, 03:13 PM   #42
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Default Re: Seaplanes & Submarines

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Originally Posted by Fred Brackin View Post
However, in light of the excerpts provided (and thank you very much for those) it seems likely that Verne intended a sort of chemical process.
Yes, sodium amalgam batteries, with the sodium extracted from seawater. Primary power for that extraction provided by coal mined from underwater sources. Relevant original text from Ch 12 from Gutenberg:

Quote:
— Le sodium ?

— Oui, monsieur. Mélangé avec le mercure, il forme un amalgame qui tient lieu du zinc dans les éléments Bunzen. Le mercure ne s'use jamais. Le sodium seul se consomme, et la mer me le fournit elle-même. Je vous dirai, en outre, que les piles au sodium doivent être considérées comme les plus énergiques, et que leur force électromotrice est double de celle des piles au zinc.

— Je comprends bien, capitaine, l'excellence du sodium dans les conditions où vous vous trouvez. La mer le contient. Bien. Mais il faut encore le fabriquer, l'extraire en un mot. Et comment faites-vous ? Vos piles pourraient évidemment servir à cette extraction ; mais, si je ne me trompe, la dépense du sodium nécessitée par les appareils électriques dépasserait la quantité extraite. Il arriverait donc que vous en consommeriez pour le produire plus que vous n'en produiriez !

— Aussi, monsieur le professeur, je ne l'extrais pas par la pile, et j'emploie tout simplement la chaleur du charbon de terre.
There's some more detail of both the batteries and the coal mining later on in the book. It should be noted that the cheap English translation (the one in the public domain) is pretty terrible with the technical details, when it doesn't simply omit those passages entirely. There's a much better translation from the Naval Institute Press that restores them, but it's still in copyright.
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Old 10-02-2010, 08:08 PM   #43
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Default Re: Seaplanes & Submarines

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Were not the novel, but the 1954 movie. One of several changes it made.
Yes, now that you bring it up I think that's where I recalled it from. The 'sodium seawater' battery idea is pretty cool, although atomic power is just as much handwavium. Season to taste for your specific campaign.
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Old 10-02-2010, 08:20 PM   #44
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Default Re: Seaplanes & Submarines

I'll clarify that by "sudden" storms I'm talking about from 10-15 minutes warning. Even the slowest-diving subs can submerge in under three minutes and the fast-diving ones in under a minute. OTOH, a surface ship can't get very far in 15 minutes.

I have not quite decided how frequent I want them to be (including duration and average time between storms). This will probably become clearly once I decide on *why* there are sudden, violent storms. They could be natural, technologically influenced or perhaps of magical/divine origin; each has it's advantages and disadvantages.

If I do decide on sudden storms of short duration, then submerged range is really not not much of an issue.

I will again say that this is a going to be a pulp setting. It should ve *vaguely* plausible, but does not need to stand up to any hard science test.
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Old 10-02-2010, 08:26 PM   #45
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Default Re: Seaplanes & Submarines

What if instead of islands you have submarine settlements. What if the planet was colonized at a higher TL, and numerous underwater cities were constructed. They then suffered a technological discontinuity and only recently have returned to TL6?
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Old 10-02-2010, 08:45 PM   #46
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Default Re: Seaplanes & Submarines

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What if instead of islands you have submarine settlements. What if the planet was colonized at a higher TL, and numerous underwater cities were constructed. They then suffered a technological discontinuity and only recently have returned to TL6?
To a certain extent, this would solve the issue of land-based aircraft, since there isn't any land ...

OTOH, no (jungle) islands do limit adventure possibilities.
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Old 10-02-2010, 10:34 PM   #47
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To a certain extent, this would solve the issue of land-based aircraft, since there isn't any land ...

OTOH, no (jungle) islands do limit adventure possibilities.
The islands could be not permanently inhabitable due to the weather.
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Old 10-03-2010, 01:04 AM   #48
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Default Re: Seaplanes & Submarines

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Originally Posted by copeab View Post
This will probably become clearly once I decide on *why* there are sudden, violent storms. They could be natural, technologically influenced or perhaps of magical/divine origin; each has it's advantages and disadvantages.
I think geography is sufficient explanation, unless you want more. IANAmeteorologist, but I understand that an ocean world without large land masses would naturally have crazy storms happening constantly.
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Old 10-03-2010, 05:09 PM   #49
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I think geography is sufficient explanation, unless you want more. IANAmeteorologist, but I understand that an ocean world without large land masses would naturally have crazy storms happening constantly.
The lack of land to act as a break means that waves propagate further, giving them more time to grow. Basically you end up with monster-sized waves. Any island that is not very, very tall is periodically going to be swamped by massive tidal-waves and/or giant hurricanes. You might have a situation where a large island acts as a break for a smaller island, but if the currents ever shift it could still get swamped. The only way to survive would be in caves that you could seal up very well until the wave had passed. There would probably be a lot of cultural effort, tradition, and customs dedicated to detecting incoming waves and storms and surviving them. Floating cities may also work; they would just ride up and over the wave if the scales were right. (i.e. city small enough to ride wave and not tip over/wave big enough). Hurricanes might still trash them though, unless the cities were mostly submerged with only a bit on top, like an iceberg.
A cluster of islands might have a better chance of long-term survival. The outer islands in the cluster would break up the waves to protect the inner islands. An island in the middle of a huge asteroid crater would also have some protection; the 'walls' of the crater would help break the waves before they reached the island in the center.
Another possibility is to have large-ish land masses to break the waves, but for whatever reason they are mostly uninhabitable and only the islands are fertile.
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Old 10-06-2010, 07:20 PM   #50
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Default Power for your world

2 billion years or so ago, U-235 was present in sufficient quantities to fission without refinement, and in one case, did so naturally. The U-235 to U-238 ratio was about 3% then--suffucient for a reactor--but not for a bomb. So there's not much handwavium needed for the power source, just the discovery of its utility.

http://en.wikipedia.org/wiki/Natural_nuclear_reactor

So, on a younger planet, you CAN have long duration subs. You can also have nuclear disasters, and create oil from water and CO2.
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