The Anti Anti Humming Bird Mod

[Der Teddy Bar]

The NYGM Anti Humming Bird mod is about removing the unrealistic hovering ability that was present with the u-boats in SHIII and that made for gamey tactics.
The crew of a u-boat, or submarine, were capable of trimming the boat to near neutral buoyancy. However, for all practical purposes hovering for any meaningful extended period of time was not possible. Hovering at periscope depth in anything other than calm waters was impossible.

It was practice to trim the boat for positive buoyancy, after all, that is where all the air is! This positive buoyancy would be done for a speed specified by the Captain or relevant officer.

The u-boat/submarine trim was something that needed constant attention and was an ongoing process of adjustments. Especially when changing depth.

NYGM initially through the use of an additional zone and a zones.cfg value were able to stop the unrealistic hovering by the u-boat.

We took this course as we were at that time unable to find a way to make the u-boat have positive buoyancy.

I am very happy with the NYGM Anti Humming Bird Mod in its current format. After using it for many months I feel that the game play benefits are immense and makes for a more realistic experience when submerged.

More realistic, but not 100% realistic. That would have you able to trim your boat to either a positive or negative buoyancy. That however is outside of what can be done in SHIII.

I have been playing with the Anti Anti Humming Bird for 2 weeks and we have decided not to use it for mainly game play reasons as well as time vs result.

The main game play reason is having a positive buoyancy will have a negative effect in some circumstances that we feel make this mod not worth pursuing.

Let me use these examples of where a player decides to stop while waiting for a convoy to approach or has damaged electric motors or batteries that stop him from moving forward.

NYGM Anti Humming Bird – While waiting for the convoy the player will slowly sink at 10 metres over 15 minutes. From periscope depth this will take nearly 3 to 4 hours to reach crush depth. So staying near the surface will not be that hard as this slow sink rate.

In the situation that your electric motors or batteries are damaged but you are not flooding, you will sink at the same slow rate. If you get to your crush depth you can always order an emergency blow. If you are lucky you will settle on the bottom of the ocean and manage your repairs and live to fight another day.


Anti Anti Humming Bird – While waiting for the convoy the player will slowly rise till you surface. The figures will be discussed shortly, for now I will use the same 10 metres in 15 minutes. In the case of the convoy, you will be in a simular situation as with the Anti Humming Bird Mod, just in the opposite direction. One downside is that you might surface and be detected.

In the situation that your electric motors or batteries are damaged but you are not flooding, you will rise at the same slow rate. While this sounds better, its not. You will rise up to the escorts and get shelled. Where as in real life the u-boat would have had it buoyancy adjusted to stop this from happening.

So with the Anti Humming Bird you have the option to surface by an emergency blow or sink to the bottom and try and last out the attack and make your repairs. Where as with the Anti Anti Humming Bird you have no choice, the only way is up.

I feel that the Anti Humming Bird wins hands down under this scenario.

The Anti Anti Humming Bird has been somewhat of a difficult child. In that to get the positive buoyancy reduced enough to enable the u-boat to maintain speed at 1 knots made the positive buoyancy so small as to be neutral. If the positive buoyancy is enough to have an impact, then you need speeds of ahead standard which is unrealistic.

The Anti Anti Humming Bird proves difficult to use because there is no way to control trim tanks in SH3, something that is necessary to ensure the boat does not broach and get detected

Also, from a basic ship handling perspective, you actually trim negative buoyant, and stern heavy when at periscope depth. This ensures the screw will stay in the water, and you won't be pulled to the surface by surface suction (the force between the upper flat part of the hull and the ocean surface). The surface suction force is very significant. As mentioned above, this is a critical area of ship handling, and since attacks must be conducted at PD in SH3, we chose to trim the boat as it would be for PD trips rather than how it would be during an evasion.


The NYGM Anti Humming Bird mod achieves it aim of keeping the player moving while allowing him/her to stop without undue penalty.

The NYGM Anti Humming Bird mod also allows the player to maintain depth at 1 knot, a realistic practice. This allows him to sneak away from the escorts.

The NYGM Anti Humming Bird works well and produces a realistic behaviour from the player.

This is why NYGM have decided to forgo the Anti Anti Humming Bird.

To get a positive bouyancy you need to adjust the MASS value from 0 to a figure just under the Displacement Surfaced value.

When 0 is used for MASS this means surfaced displacement is used instead.

Some example figures,
If I set the MASS for a Type IIa to 278, then the u-boat will need ahead 1/3 just to submerge! Don’t even worry about staying submerged at any speed other than that.

If I set the MASS for a Type IIa to 278.5, then the u-boat will need ahead slow just to submerge, but it is excessively long to do so. You also will need a speed of ahead slow (3 knots) just to stay submerged. So at speed less than 3 knots you will head towards the surface.


If I set the MASS for a Type VIIb to 752, then the u-boat will need ahead 1/3 just to submerge! Then it will be slightly off the ordered depth, so 20 metres equals 19. Then at 2 knots you will rise to 17 metres. Then at 1 knot the only way is up.

The larger the u-boat the more manageable the idea is.

The initial crash dives for the VIIB are the same though, but take 20 seconds longer to get to 80 metres, 2 minutes as compared to 1 minute 40 seconds.

To conclude, there are also some other side effects such as excessive bobbing when the wind speed increases. Yes this can be probably addressed somewhat with changing the wave stuff, but again, so much work to make this work with everything.

Anyway, it’s all here for everyone.

I must make it clear that many months ago Cmdr Gibs indicated that he knew how to do this. I have no reason to doubt him, so I am not claiming to be the first to make this discovery.