May be of interest:

From:
http://www.fleetsubmarine.com/diving.html

and
Happy Hunting!

Art

Ewwwwww! That's some kind of oversimplification because the trim ballast system and negative tank have to have some water in them. The boat would have to have a fair amount of reserve buoyancy with the main ballast tanks full or it couldn't carry any cargo or people. Once a tank is empty, you can't make it any lighter.

I think the statement is probably correct with full MBTs and a default amount of water in the trim and neutral buoyancy systems. Davey? What's your take?

I should know better than to 'dance' with you again RR ..... lol - however I didn't want to quote the entire page. They go into greater detail on the website. The weight of the boat would of course include 'cargo & people'

http://www.fleetsubmarine.com/dynamics.html is also helpful.

Happy Hunting!

Art

thats an equally good point, i was only thinking of accidentally being detected if something went wrong yet like you say to survive you dont want to sink either so being detected on the surface gives you a better chance to survive than crush depth. :up:

Main ballast tanks are always completely empty or completely full. Their purpose is to provide or eliminate the overriding postive buoyancy that holds the boat on the surface. The trim tanks are used to regulate the buoyancy of the boat.

While in port between patrols, a careful accounting of how much fresh water, fuel oil, lube oil, hydraulic fluid, torpedo alcohol, stores, etc., etc. is brought on board and the weight of all this is used to figure the initial compensation. One of the first things that is done after clearing the harbor outbound is to conduct a trim dive. It is not uncommon for the boat to have trouble submerging or maintaining depth at this time. As much time as is needed it taken to properly adjust the ballast compensation by flooding water into or pumping it out of the trim tanks. The goal is to obtain perfect neutral buoyancy so that a minimal use of the planes will maintain depth. The whole time the boat is at sea, a running tab is kept on consumables useage and the compensation is periodically adjusted as needed. Trim dives usually took place once a day.

In reality, on the fleet boats, perfect neutral buoyancy is virtually impossible to achieve. The manually operated trim and drain system, while a very good design, was just not sensitive enough to get to that point.

From a submariners standpoint, if you can't get to neutral buoyancy you would default to a slight positive buoyancy. Contrary to popular belief, true crash dives did not happen all that often with our boats (radar gave you enough warning). If you had to go down quickly you could flood the negative tank and you would go down like a rock. I heartily agree with the other posts that it is far better to broach (although obviously not desireable) than to sink. You at least have some chance at survival if you broach, but if you exceed crush depth you WILL die.

Dave

www.pigboats.com

Dave,

love your posts, some of the very best I have read here. Keep educating us, this stuff is great!

tater

Agreed. It's great to hear from a real submariner who knows what he's talking about.:up:

Thanks guys. I really appreciate it. For a real world example of the importance of proper ballasting, surf over to http://pigboats.com/dave5.html when you have a chance (insert shameless self-promotion here!) :lol:

Dave

Thanks for the detailed description on how these beasts swim Davey. Informative site too. :up:

I wish the sim had things like trim dives, equipment malfunctions, (that aren't related to battle damage) training crewmembers, etc. There's so much more to a patrol in a sub than a leisurely cruise between ship sinkings.

I agree that a random equipment malfunction feature should be added. It shouldn't be too hard to do and would add an extra level of realism to the game.

Thanks for the kind words on the site. My partner Ric Hedman does all of the grunt work, I just do the writing.

Dave

Excellent read, Davey.

Goes a long way to show how dangerous even small changes could be. Only thing I can add, is, now I can say with absolute certainty I'm not the only man ever hit in the head with a toaster.

No Kidding! That is the single most egregious omission in the game. Equipment failures were the third side in the war...you were always fighting two enemies.