Silly Operation Monsun question

[shake307]

I have been playing Silent Hunter 4 off and on for a while now. I recently downloaded Operation Monsun and OMEGU, with all the patches and goodies that come with them. I was under the impression that, historically, GHG passive sonar worked on the surface. Was this not modeled in OM, or am I mistaken? Also, does any passive sonar work on the surface for the U-boats? I appreciate any reply, as I am both interested as pertaining to the game and in history.

Running

OpsMonsun_V705
OMv705_to_V720
OMv720_Patch5
OMEGU_v300
OMEGU_v300_Patch7
OM_Pac_Env
KiUB_English
AOBF 16-9 Res

[Sailor Steve]

I've heard similar stories involving American fleet boats, and it was modeled into regular SH4, but I don't know if Lurker shut it of for Op Monsun or not. I do have a problem with the whole concept though, for the simple reason that if any passive sonar can hear any ship on the surface (i.e. sub hearing skimmers) then any other passive sonar should be able to hear any other ship on the surface (i.e. skimmer hearing sub), and I know that never happened. Thus I find it hard to believe that subs could hear other ships while on the surface.

On the other hand, if someone can show actual reports of it happening then I might be willing to listen (pardon my pun). :sunny:

[BigWalleye]

It depends on what you mean by "worked." GHG "worked" in the sense that, unlike KDB, the sound heads were not actually out of the water when the boat was surfaced. But GHG was still basically useless when the Diesel engines were running. And all WW2-vintage hydrophone systems were swamped by propeller and flow noise when the boat was moving at any speed above a knot or two. Then there is the issue of water surface noise, which is considerable, depending on sea state. Surface ships got around this by having hydrophone arrays which were oriented downward (or at least insensitive above a plane about 10 feet below the surface). That's fine when you are on the surface listening for submarines. But a submarine's hydrophone have to be able to listen to sounds above its depth. Too close to the surface and surface ambient noise would saturate the hydrophone. IIRC, KM doctrine called for listening from a depth of 30 m while stopped or at "schleichfahrt".

Remember too that sound follows an inverse-square law. Signal level diminishes by a factor of four when the source is twice as far away. So all these noise sources - Diesel engines, flow noise, and surface ambient - would severely lower the range at which a surface ship could be detected. If ambient noise level is half the volume range of the hydrophone, then the hydrophone's maximum detection range is reduced from, say, 20 km to 5 km. At 5000 m, the lookouts could probably see the other vessel!

Both SH3 and SH5 have incorporated modding fixes to limit or prevent effective use of hydrophones by a surfaced U-boat.

Here are a couple of sites which describe German WW2 hydrophone systems:

http://www.uboataces.com/hydrophones.shtml

http://www.cdvandt.org/GHG1996.pdf

Both make a point to mention the virtual uselessness of the systems when surfaced.

[merc4ulfate]

You can read the documentation on fleet boats here:

http://www.hnsa.org/doc/fleetsub/sonar/index.htm

[shake307]

Thanks for the timely response, everyone. All very interesting stuff that does a fine job satiating my curiosity. I suppose I should just get used to porpoising my Type VII.

[Sailor Steve]

It depends on what you mean by "worked."
Good points. A great many things I didn't think about. :yep: