How hard is it to do harbour denial ?

[Kapitan]

This is a mission run by many navies around the world to test the defenses of the harbors and how quick the surface or air units can respond to any submerged threats.
The Royal Navy do something very similar although they mainly will use the perisher training course to do this kind of operations they call it inshore operations for the most part.


You should note that this type of mission is a lot harder than it actually looks, the submarine has almost every advantage if it can stay undetected, so for this mission I kept the opposing submarine as own side so it would show up and I will endeavour to show you how its done from both sides.

Moving out of port can be tricky, for this map which Stew1 made with all the lines ports and labels its a fairly straight forward move astern then turn to port.
I had no need for the APUs but in the African bees nest mission they do come in very handy and remember if your going to use them no faster than 8 knots !

Inshore waters are dangerous for both the surface unit and also the submarine and here's why.

The submarine has limited scope to maneuver its in shallow water its diving and evasion options are very limited and if its in a bay area then it hasn't got open water to run too or a layer to hide under the type of bottom can also be a problem, Rock bottoms bounce sound waves like a mirror while mud and sand absorb them some what.

It also has a speed issue, at shallow depth a submarine travelling fast will cavitate at lower speeds, so any commanding officer will have to monitor speed and depth below the keel very rigorously.

Another major threat is surface traffic, many submarines will employ a go deep circle (this is calculated by the closing speed of the two vessels and does vary) but in inshore waters depth is limited thus the submarine also has to keep track of all surface units.

The Surface ship may seem to hold all the cards but it actually doesn't, shallow water means no towed array so now your reliant on the hull sensors, while I do have the option to deploy the helicopters there's only a certain area I can drop buoys in, so if the submarine doesn't come up the deep channel the chances of me locating it with buoys is minimal.

Being in shallow waters there is a certain amount of reflection from the bottom active sonar in this instance can cause you a headache sometimes even giving you false returns, so realistically I will only use passive sonar.

Because surface ships cavitate much easier than a submarine I have to be aware that my own noise can betray me thus my own speed is limited while hunting. (Perry quiet speed is 0-5 knots)

Another hinderance for both is surface traffic, it can play havoc with the sensors.

This mission is taken in the Baltic sea from Oslo, the task is to defend Oslo from attack by a rouge submarine in this case an Ula class conventional submarine.

Conventional submarines are excellent littoral combat units, they are hard to detect normally but in shallow waters more so and the Ula is a very quiet boat.

As you can see in the above screen shot I have laid out a typical T pattern across the estuary, this covers all the deep water in the area, the main reason behind it is due to the likely hood that a submarine will want to keep a decent amount of water under the keel so it can get out of the way quickly without grounding.

You will also notice I have laid out my own course and it is close to land, the reason why I have done this is to keep me out of the way of my own buoys, but chiefly if your playing MP many sub drivers do not set their torpedoes to run in the shallows.
I can tell you after many years of playing both sides that setting the torpedo to be able to operate in the shallow areas is the most over looked part of the game, many torpedoes fired will simply run into the bottom.

The other reason for running shallow is that the sensors on the submarine find it harder to detect you, so I am using the environment to my advantage here.
By Running in the shallows and also running slow 5 knots I am trying to present myself as the most difficult target I can be.

In this mission for speed I used two helos to lay the field but in reality you only need one hence I recovered one part way through as its not needed.

Because of the shallow water and the environment the helo cannot use its full range of buoys, there are three main types of buoys carried on the helo in two forms shallow and deep.

DICASS shallow 90ft deep 800ft
DIFAR shallow 90ft deep 400ft
VLAD shallow 400ft deep 1200ft

The deepest points in this mission are only 503ft deep the average is just 265ft, there is no layer, the bottom is rock so your only able to use DIFAR or DICASS shallow, when in reality your best buoys in the game are DICASS and VLAD.

So now your fighting with one arm behind you back and to top it off you have merchant traffic transiting the shipping lanes this put another dimension on the whole thing.
As a sub driver in confined waters the perfect place is behind or below one of these merchants and if you look closely at my ASTAC you can see why.


Top left you can see I have classified the type 210 (Ula) she is hiding in the wash of a car ferry heading North to south, on the other side is a container ship heading south to north, this is the only time I could classify this contact (1010 on the nav map) , it was for only a few seconds before it disappeared in the ferries wash (3rd screen channel 02)

The Passive sonar couldn't get a decent read on the Ula and you can see with the noise the ferry is making, the Ula is in there somewhere as well.


Overall after some time trying to find the boat my time limit expired the Ula had already passed me by and quite close only 3.9nm and yet I couldn't hear her and I only held a brief contact for no more than 30 seconds to a minuet.

In this scenario the submarine would have easily won out, it was able to get past me and the buoy field, this shows you just how difficult inshore operations and harbor denial is and if you use the terrain right you can avoid being detected yourself.
So some of you may ask why did I keep the submarine link data information to show on my nav map well this is to show you exactly where she is and what my sensors are doing and how I am trying to find her.

[Stewy1]

Thanks Kapitan, that was a good read.

As I'm sure you know, NATO have released (most of) their ASW exercise manual here - https://info.publicintelligence.net/...rineManual.pdf

Good for scenario making - and even training

Fighting a 1980s-style World War Three in the Baltic would be have been brutal, I think...

Cheers,
Stew

[Kapitan]

Indeed I do have a copy of this and it is a good read

There's quite a lot online now and I'm surprised even with the publications I'm still not allowed to talk about things or publish articles based on the documents.

EDIT: Just a thought here think i should write up a manual with tactics and stuff?

[Stewy1]

write up a manual with tactics and stuff?

I'd be interested!

Yeah, it's amazing that most of the ASW serials are public. I tried searching for the OSINT surface warfare training serials, but got no joy.
Stew

[Kapitan]

I shall see what i can do atm with the current situation my work load has just tripled.