Hydrophones

[Kaiser Kirk]

Greetings,
First of 3 Posts.
1. Preamble
2. Development, use and tactics.
3. "Miscellaneous Weights"

Hydrophones...what are they, how big are they, how effective, what tactics... um... not a topic I've delved into much in the past.
This Christmas I ordered a book, which among other things had a surprisingly long section on hydrophone development and use.
It also had information on durability, tactics, and pictures of many of the installations.

I've made an effort to convert that information into a format usable by use in Navalism, tied to our tech levels. 
The result is "Hydrophone packages" we can install on our ships- which include the lightweight but fragile hydrophones with the room, operators and spare equipment to operate them.
There is also a similar effort in regards to Anti-submarine armament.

Snip has bravely served as sounding board and editor,  boiling down my signature complexity and length of prose into something more palatable.

[Kaiser Kirk]

Hydrophones :

Development
Underwater microphones for maritime communications were introduced as a commercial venture about 1911.  This 'off the shelf' technology was quickly adapted for submarine detection in 1915.  This basic form, of a microphone in a rubberized nipple, saw several varients and efforts, including hand-held booms over the ship side, "through hull" mountings, towed arrays and fixed subsea arrays.  Concurrently, research was ongoing on better versions with new receivers, electronic amplifiers and filters, and more capable hull and towed mountings.

Utilization
1910 : The 1910 technology hydrophones are very simple and of limited range. Engine and hull noise rendered the hydrophones unusable while the ship was underway, giving rise to "sprint and drift".

Experiments showed could be done by turbine powered destroyers as well, if carefully timed. Given the cruise speed of a battle squadron, an intercepting submarine needs to be in a narrow arc ahead. Half squadrons of destroyers would leap frog and conduct "sprint and drift" along the battleline's course.

Typically submarines closed to 500-2500 yards prior to trying to fire, and a drifting "Basic Hydrophone package" could pick up a slow moving submarine at half that range. An "Enhanced Hydrophone package" vessel could pick up a slow moving submarine at the outer edge of that range.  Early towed arrays were introduced, tailing the hydrophones far from the engine and hull noise and, allowing slow (6knot) movement but detection up to 4000m. These towed "Eels" were fragile and would fail within a day or two, limiting use. 

As hydrophones lost directionality very close to a target, multiple vessels coordinating by radio phone were necessary to "hunt". A typical arrangement may be several converted fishing vessels and one faster torpedo gunboat which would close on the target.

1915 :The 1915 technology hydrophones gained several improvements. At this stage, silenced versions of the various noisy engine parts are introduced, substantially reducing that noise source. With amplifiers and filters, the "basic package" improved to allow detection of submarines out to 4000m. 

The "Enhanced package" included greatly improved multi-hydrophone rotating directional arrays, passive blister mounted arrays, and the  "Nash Fish" towed array. While the towed arrays had a limited life (~72hrs) until the cables failed, both the towed and blister arrays can be used while the ship is moving at up to 10knots, with a range of 6000m. A ship with the "Enhanced Package" which "sprints and drifts" can use it's hull mounted directional hydrophones to detect submarines in optimal conditions up to 20,000m away.

1920 : The 1920 technology hydrophones introduce enhanced towed arrays such as "the Dinosaur" with a range of 40,000m.  At this tech level, early sonar comes into service in a keel dome, and can be used at 1000m and up to 25knots, allowing a single vessel to both do the detection and final attack run if necessary.

Anti-Submarine Armament
Baseline
"Harpoon" : Literally an explosive tipped harpoon. Designed to be thrown from a torpedo boat rushed to the submerging submarine and set to detonate under the water. More likely to damage the sub than kill.

1910
"ASW Kites" : The early anti-submarine consisted of towed cables with explosives, kept taught by one or two underwater kite. These only work if the vessel overruns the submarines' position and the explosives contact the sub.  Both are limited to 12 knots or less.

"Nets" : Nets were extensively used for both harbor and channel defenses, and could be deployed between two trawlers.  Nets were frequently fitted with small electro-contact mines which would detonate when drawn near the hull.

"Depth Charges" : Too-small depth-charges rolled off stern,  timed detonation set by pull-out cord.

1915 :
"ASW Paravane" : An advanced form of the Kite, usable up to 25knots. 

"Depth Charges" :  Depth Charges, Thornycraft Depth Charge Throwers, 40m range. 

"Howitzers": Ahead firing field howitzers aiming at periscope. Special flat nosed diving shells.

1920
"Howitzers" : Lightweight ahead firing howitzers or standard 75mm+ guns firing a 200lb stick-bomb at the periscope and set to detonate at 30feet. Very early precursor to later spigot-mortar arrays such as Hedgehog.

"Depth charges" : "Y" guns firing two DC out to 80m, and 600lb DCs.

[Kaiser Kirk]

Hydrophones in Navalism.

As detection systems, they do not count as "Armanent".
They come in a "Basic Hydrophone set" 
and an "Enhanced Hydrophone Set".
Their effectiveness is dependent on the nations Submarine technology level. 

The "Basic Hydrophone set" consists of hand-held booms over the ship's side and magnetaphone diaphrams mounted inside the hull, and room for trained operators and parts. Typically this is one omni-directional hydrophone for each side, and a directional hydrophone. This  can be installed dockside in a Basic Refit.

The "Enhanced Hydrophone set" consists of through-hull rotational mountings, hull mounted hydrophone arrays in a blister, and towed arrays... and room for trained operators and parts. This installation must either be built in, or part of a Basic Refit requiring a drydock.


Miscellaneous Weight
5t : "Basic Hydrophone Package" : 3 boom hydrophones, in-hull PGS internal diaphram and omni-directional mounted arrays. A 300ft electrified cable allows the vessel to trawl for stopped subs on the seabed.

15t : "Enhanced Hydrophone Package" : 3 boom hydrophones, K 3-Tube style through Hull directional array, WV-hull blister directional array., 3 towed arrays. A 300ft electrified cable allows the vessel to trawl for stopped subs on the seabed.

10t : 1920 Early Sonar & keel dome, spares, operators


Anti-Submarine Armanent Miscellaneous Weight
These shall be specified under miscellaneous and can be changed with a Basic Refit.

1910 ASW
1t per 10 ASW harpoons & storage locker
1t per 60m2 Electro-contact mined nets
1t per ASW Twin Kite : <=12knots, upgrades with tech to ASW Paravane
1 t per 10x 90kg depth charges, including rails. DC lethal volume :4200

1915 ASW
1t per ASW Paravane : <=25knots
1 t per Thornycraft Single-DC thrower 40m.
1t per 5 x 195kg depth charges, including rails and handling gear. DC lethal Volume :1,437,000

1920 ASW
1t per 10 x 100kg "Stick-bombs" to fire from 75mm+ light howitzers or deck guns. 
1t per 3x 280kg depth-charges, including rails and handling gear. DC Lethal volume : 3,053,63
1t per "Y" twin-DC Thrower 80m.   

[Kaiser Kirk]

Feel free to point out horrible problems, pose questions, or state concerns.

[Desertfox]

10t : 1920 Early Sonar & keel dome, spares, operators

What does this do? Is it an add on? Or is it required?

The weapons are a bit too detailed. I would just say you can add ASW weapons in 1t increments.

[Kaiser Kirk]

1920 : The 1920 technology hydrophones introduce enhanced towed arrays such as "the Dinosaur" with a range of 40,000m.  At this tech level, early sonar comes into service in a keel dome, and can be used at 1000m and up to 25knots, allowing a single vessel to both do the detection and final attack run if necessary.

That's what it does, and it is an independent item.

As for the armament items, they are in 1t increments.
While eventually everyone will have "Y" throwers and heavy DCs,

Rght now most folks are at lower tech levels, when those didn't exist.
So I went ahead and covered the earlier weapons.

There may be merit towards simple tonnage towards ASW weapons.
However, there are differences in how one would employ them based on what you mount.
So this should give players options on how "big" and what type an anti-submarine armament set up they want, and vary it by vessel role.
OR one can simply go with a bunch of DCs...or lots of harpoons if that tickles your fancy. 

[snip]

The weapons are a bit too detailed.

laughs in original list this is not that bad.

[The Rock Doctor]

Nothing about it really bothers me, but I'm kind of wondering about the implementation side of things.  I've had the 1910 sub tech since the end of 1912 and have built a fair number of destroyers since.  For those units, can I skip the refit and simply allocate miscellaneous weight from the type's Weight Reserve toward 1910 hydrophones and ASW kit?

[Darman]

ASW harpoons

But what if we want BIGGER harpoons?  Can we build turret-mounted harpoon launchers?

[The Rock Doctor]

ASW harpoons

But what if we want BIGGER harpoons?  Can we build turret-mounted harpoon launchers?

Obviously the answer should be yes - provided you post some news stories about its development.

[TacCovert4]

Nothing about it really bothers me, but I'm kind of wondering about the implementation side of things.  I've had the 1910 sub tech since the end of 1912 and have built a fair number of destroyers since.  For those units, can I skip the refit and simply allocate miscellaneous weight from the type's Weight Reserve toward 1910 hydrophones and ASW kit?

I think that should be allowed for ships laid down before 1hy16 that would ordinarily have ASW kit and have tonnage reserves or had ASW kit denoted but not within the new rules for it.  Just make it an 'across the board' rule.  I know that I don't really have any ships that would meet it at the moment, but I've got my 1917 DDs designed and they will be so equipped.

[TacCovert4]

10t : 1920 Early Sonar & keel dome, spares, operators

What does this do? Is it an add on? Or is it required?

The weapons are a bit too detailed. I would just say you can add ASW weapons in 1t increments.

Looks like that would be ASDIC or SONAR as opposed to hydrophones, so an active measure for sub hunting rather than waiting for the sub to make noise.  FAR more effective overall especially coupled with hedgehog.

I rather like the detail on the weapons.  As someone who is operating a decent number of subs compared to total fleet strength, the differentiation is good.  Subs come in all sizes, and the different weapons denote different effectiveness against subs of varying sizes.  I wouldn't want to be on a 125 tonner hit by an explosive harpoon, but on a 500 tonner it might just irritate me that the paint has been scratched.

[Darman]

I wouldn't want to be on a 125 tonner hit by an explosive harpoon, but on a 500 tonner it might just irritate me that the paint has been scratched.

This is why Iberia needs ASW cruisers with GIANT quintuple ASW harpoon turrets.  Well, that and also for hunting megaladons. 

[The Rock Doctor]

*Checks map to see who holds territory around the Marianas Trench*

[Kaiser Kirk]

Nothing about it really bothers me, but I'm kind of wondering about the implementation side of things.  I've had the 1910 sub tech since the end of 1912 and have built a fair number of destroyers since.  For those units, can I skip the refit and simply allocate miscellaneous weight from the type's Weight Reserve toward 1910 hydrophones and ASW kit?

I think that's fair.