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Old 04-16-2019, 07:59 AM   #1
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Default The Boyle's Law update: What impact will this have?

I've looked at the wikipedia article for Boyle's Law and can't get my head around how it might affect gameplay. I am figuring that the change in the ballast tank size is linked, but I'm new to all this so ELI5 if possible.

Also, first post, and loving how much there is in this community!
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Old 04-16-2019, 08:21 AM   #2
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Hi lothario Welcome to Subsim Wolfpack may take over your life and when your out shopping you may find that you have a pack of three green light bulbs and a pack of three red lightbulbs in your basket when you get to the checkouts.
Also on a evening when a car exhaust backfires as it passes your house you order a crash dive 30 degree dive bubble and hard to port.
Its nothing to worry about your becoming acclimatised to your new surroundings.

Last edited by blackswan40; 04-16-2019 at 08:31 AM.
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Old 04-16-2019, 12:26 PM   #3
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The change in ballast tank size is unrelated.

My attempt at an explanation:

Before: You put a certain amount of air in the tanks, which displaced a certain amount of water. The same amount of air and water would remain in the tank until you either put more air into the tanks, or open the vents to let air out and water in. There was no gauge for the amount of air in the tanks, but as the only relevant variable was the amount of water in the tanks, this wasn't needed.

Now: You put a certain amount of air in the tanks (measured as "kg/cm2"). At shallow depths, where the water pressure is low, this air will have greater volume and displace more water than at at greater depths. Thus you will lose buoyancy ("up-force") when descending if your tanks are not already completely full with water (the amount of water will increase), and gain buoyancy when rising if there is both air and water in the tanks (the amount of water will decrease).

Note that since the air you put in the tanks expands when the sub rises, you can put more air in the tanks than there is room for when the sub is surfaced. The air gauge shows a pressure value in kg/cm2: This is the pressure the air would have if there was no water in the tanks.. Thus, the pressure gauge shows the amount of air in the tanks, rather than the actual pressure.

A convenient unit for measuring pressure is atmospheric pressure (the air pressure at sea level), and 1 kg/cm2 equals approximately 1 atm. At the surface, the external air pressure is 1 atmosphere, and the water pressure is about 1 atmosphere for every 10 meters under the surface. The ballast tanks will be empty of water as long as the air gauge pressure is higher than the water pressure at the depth of the sub. For example, if you start at 100 m, and put 5 kg/cm2 worth of air in the tanks ("5 atm"), then the ballast tanks will be empty of water at about 50 m.

Thus, only 1 kg/cm2 of air in the tanks is necessary to completely empty the tanks at the surface, but then the tanks will not be empty before you reach the surface, and ascending will take longer time. If you put in more air, you "waste" some high pressure air, but you can surface faster.

Last edited by jarlemag; 04-16-2019 at 12:35 PM.
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Old 04-19-2019, 05:09 PM   #4
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@jarlemag: Thank you very much for that explanation. Exactly what I was needing! This makes things more interesting as well. I can see this giving a Dive Master something to actually worry about when manoeuvring at depth, well, aside from battery levels.

Thanks again!
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Old 04-19-2019, 10:31 PM   #5
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Good POST.................... +1
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Old 04-20-2019, 07:25 AM   #6
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Excellent description.
The first truly good subsim was Aces of the Deep. Then there was Silent Hunter III. Now Subsim presents: Wolfpack.
Good hunting and don't forget to close the hatch!

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