Hydrophone check

[balto63]

Hi to all Kaleuns
How often and at what depth do you perform an Hydrophone check while on surface ??
Every one hour al 25 mt below ??

TIA

[GoldenRivet]

I hydrophone check at 40 meters depth. though i dont think depth has anything to do with how well the hydrophones work.

I usually hydrophone check when i have been without visual contacts for several hours. i always hydrophone check and actually hunt by hydrophone exclusively in known high traffic areas and choke points.

as a word of caution, some escorts in GWX "drift" meaning they will run at cruise speed for some time and then suddenly slow down to about one knot for several miles... you probably wont detect these guys on hydrophone. i learned this lesson when surfacing within abotu 6km of a clemson class escort. i escaped, but just by the skin of my "scrote".

when surfacing from a hydrophone check i recommend the following procedure

1. Order periscope depth at ahead slow speed
2. using the observation scope, scane the full 360 degrees on zoom one and then again on zoom 2 then lower the scope.
3. when you are confident there are no surface contacts proceed to ahead flank.
4. when the boat achieves its maximum submerged speed, order the boat to surface
5. once on the surface and confident that there are still no surface or air contacts, order a normal engine speed.

why i use this method.

1. it prevents me from surfacing next to clemson drifters!!!
2. by ordering ahead flank and achieving best forward speed while surfacing, once i actually surface, the extra speed will help submerge the boat again should a crash dive be warranted.

[Elmer Kosterman]

I think Goldenrivet is right about depth having no affect on hydrophon performance.

As far as how often to do a check. I figure so: if my cruising speed is 5.75 knots (in a type II), and the range of the hydrophon 20 kilometers (estimate), then submerging every two hours or so will prevent ships travelling at 6 knots (slow traffic) from sailing passed me just out of visual range (8 km). If your cruising speed or the speed of intended targets is higher, then you've got to submerge more often. If the range of your hydrophone is greater, less often.
Some people stay submerged as often as possible, and I like to wait submerged at key high-traffic areas.
I asked a similar question some time back: www.subsim.com/radioroom/showthread.php?t=133456

[balto63]

Thank you both kaleuns
Weather influence the sonar performance, I mean with bad weather, as always in my patrol, I've to go deeper to exted the range of the hydrophone ?

TIA

[Jimbuna]

In good weather I go to periscope depth. In bad weather I go to 50 metres.

Either way I just drift and listen for an hour.

[balto63]

Thanks a lot jimbuna

Happy hunting to you !! Happy hunting to you !!
Happy hunting jimbuna happy hunting to you :rotfl: :rotfl:

[Kipparikalle]

Does the weather really affects the endurance of hydrophone?

[balto63]

Originally Posted by Kipparikalle

Does the weather really affects the endurance of hydrophone?

Following what jimbuna wrote the answer is yes.

Should be very intersteng to know how is modelled, in harpoon II the effect of the weather on all the sensor could be seen very well on the tactical maps and in the weather maps where you could see precipiation, cloud cover, height of the wave and the force of the wind.
It's a pity that we cannot get a weather maps prior to our patrol, KM has put also automatic weather station in a lot of place during WWII.

Hi kaleun Kipparikalle

[papa_smurf]

Normally I go to periscope depth to perform a hydrophone check every 2 hours. I rougher weather I got to around 40m.

[danoh]

Once I have reached the high-traffic shipping lane I want to hunt in, I always run at perisope depth/silent running until the batteries are down to 50%. Then I surface until they recharge, and repeat.

It sounds, however, like the 2-hour interval is favored by many. Is this because it allows you to cover more ocean and still accomplish the same thing?

It also seems like in rough seas you can stay on the surface and still keep getting constant hydrophone checks as the waves bounce you under.

Anyone know what the actual historical procedure was?

[Elmer Kosterman]

The actual procedure might have varied from boat to boat. In general, BdU encouraged captains to stay on the surface as much as possible. Here is a quote from the submarine commander's handbook (hnsa.org/doc/uboat/index.htm):

27.) It may also be advisable to remain submerged in misty or foggy weather. In poor visibility, the approach of ships can be more easily detected underwater [from the sound of the ships' engines] by means of the hydrophone, than on the surface by the look-out.
28.) This possibility of using the hydrophone to help in detecting surf ships should, however, be restricted to those cases in which the submarine is unavoidably compelled to stay below the surface. The hydrophone must not lead to inactivity [passivity] underwater, which would be wrong; it is an auxiliary instrument and no more, and can never be a substitute for ocular perception and surface viewing. As soon as visibility allows, the, place of the submarine is on the surface. Otherwise valuable opportunities of attack are lost.

As far as the effectiveness of the hydrophone in bad whether, I'm sure it was affected in real life. In the gtame, I've heard that escorts have a hard time with detection in bad weather (allowing one to travel undetected at a higher speed, for instance), but the only difference I've noticed in the sub is that the hydrophone goes out when the boat broaches the surface in heavy seas. I've never tried using the hydrophone from the surface in heavy seas like Danoh suggested, but I'd think the boat wouldn't be under long enough to scan in all directions thoroughly.