How to maintain depth with zero speed

[joho]

Originally Posted by TarJak

Just like in real life this is something that is extremely difficult. Assuming you use GWX the bouancy model is designed to model this diffuculty and therefore what you are trying to do is impossible.

But i must have been possible to adjust. If the boat is acending , increase weight, decending decrease or. I dont need the uboat to maintain an exact depth. But I wanna be able to adjust when its going one way or the other.

[Otto Von Strunf]

when u are abowe cca 200m and u stop your engines pres D, when u start decending pres A, then D again etc, etc... When you are below cca 200 m, use combination of A and S, but if you are too deep (220 - 240) you will need to use balasts. you can do it maximun 3 times, blow your balast and when you reach 180 press A, then u will start to decende again on 240 do it again.

[TarJak]

Or you can just set the depth you want to move to using the depth guage. In reading your first post I assumed you wanted to stay at a set depth. The boat will slowly rise or fall without the engines running in a simulation of the air ballast tanks. How fast you move up will depend on whether you blow your tanks or not. Diving without power is harder due to the GWX setting of slightly positive bouancy.

[Subject]

Or - you go get the "Neutral boyancy mod for GWX" to get rid of that modelling.

Some like to play that the crew is there to handle the boat and obey orders

[melnibonian]

If I remember correctly in the new version of GWX the reduced positive buoyancy will be default. Until then just use the optional "Reduced Buoyancy Mod".

[seafarer]

Originally Posted by Subject

Or - you go get the "Neutral boyancy mod for GWX" to get rid of that modelling.

Some like to play that the crew is there to handle the boat and obey orders

If reality is your desired goal in the game though, even the best crew could not keep a boat at constant depth without forward momentum and use of the control surfaces (planes). A submarine in a state of neutral bouyancy is a delicate balancing act and practically impossible to acheive with mechanical means. Sure, you can pump water in and out of tanks, shift water between trim tanks and such, but true neutral bouyancy is a knife's edge state that you will keep slipping off of.

The boat, for one thing, is not stationary. It is subject to currents. Those currents will move it through water with subtly varying temperatures/salinity, hence subtly varying density. As it sinks, it's hull compresses, so it's volume changes slightly, so ballast needs to be released. So, true neutral bouyancy is fine in theory, but impossible with real life machinery.

Plus, pumping out water at depth takes a lot of power, as you have to pump out against the external pressure. It's also thus difficult to percisely meter pumping out very small amounts of water to maintain neutral bouyancy and level trim.

It's one of those classic instances where the theory is relatively straightforward, but engineering a 1000+ ton machine that can exactly implement the theory is the challenge.

[Chock]

Unfortunately, SH and pretty much every other sub sim is not totally realistic in this area, as it would probably require a supercomputer running all sorts of chaos algorithms to model it at least well, if not truly realistically. So the reduced buoyancy in the sim is about the best simple comprimise.

As seafarer notes, if you ever bring a boat to a halt out on the open ocean in real life, the amount of drift you get on currents is absolutely frightening, and you can quite easily drift a mile or more in ten minutes near estuary outflows, which extend fo many miles. So in theory your sub shouldn't even be able to remain laterally stationary either, as it would require thrusters to pull that off. And that drift would put you in water with altering densities, as the temperature, salinity, etc fluctuated.

Real U-Boats, and modern subs for that matter, will drive dynamically to the depth they want, and then try to maintain that depth by altering trim, but some fluid movement over the planes is the simpler and more desirable method, and the problem gets even worse if you launch a torpedo and suddenly lose all the weight of it as it leaves your sub, subs being equipped with compensating tanks which flood to aleviate the problem a little.

This is why most WW2 subs would perform a daily 'trim dive', to give the chief an idea of what was a likely setting required for maintaining position at various depths given the sub's altered weight from food consumed, oil and lubricants used, ammo spent etc, all of these changes alter the calculation. Even the sub itself gets smaller as it dives deep and is compressed by the water pressure!

I was reading the other day that when the Pittsburgh was launching Tomahawk cruise missiles in the Gulf War, even though in theory it can launch them in a matter of minutes, the skipper actually started the countdown to launch twelve hours beforehand, and elected to slowly approach the launch point from the start of that countdown, so that he would be able to ensure he was at the correct point and depth at the right time, and that's a modern nuclear sub with computers assisting the trim calculations!

So if it's a bit tricky to maintain depth in the sim, that's definitely realistic, even if it is simplified.

Chock

[Subject]

You do not need speed to dive to 180 meters. Maintaining depth do require constant monitoring and a lot of work, but that's why your boat is full of men
Please don't spread myths.