Modern Naval Warfare - Navy Log Book #2
Welcome to the second Navy Log Book. This time we decided to get more technical and give
you a tiny peek of "behind the scenes" mechanics.
Submarines by nature are some of the most complicated vehicles ever conceived. In complexity
they are comparable only to spacecraft and additionally submarines have to operate in a vastly
more hostile environment even if nobody shoots at them.
Your Virginia class sub submerged, well trimmed and underway.
In order to pilot a submarine in average you need to control the propeller turns, the rudder, two
sets of planes (one aft and one fore or on the sail), two sets of main ballast tanks (fore and aft)
and an assortment of compensation and trim tanks. Additionally you will need to keep your eye
on the environment as factors such as sea state, sea temperature, salinity etc. play a part in the
seakeeping of the boat. As one of our consultants (and active NCO) has pointed out if you take a
submerged sub out of the Mediterranean and in the Atlantic through the Strait of Gibraltar the
sub will start to sink due to different environmental factors (e.g. salinity). All of this is just to
move from point A to point B without taking into account any navigation or operational needs.
No it is not as easy as driving a car and that's why it takes from 2 to 4 four people to do the job
depending on the sub class.
In previous US submarine classes there where four people driving the sub:
In the Virginia class subs and through the use of automation these four positions where
consolidated into two:
The pilot and co-pilot station in a Virginia Class Block III submarine. Along with the main
operating displays all the analog controls and gauges are also working.
In fact the "fly-by-wire" and "auto-trim" systems are advanced enough that the two positions
are for operational reasons and redundancy rather than for technical reasons. However there are
manual overrides for all the automated systems and (you guessed it!) they are duly modeled.
"If that's the case" then you'll ask "why there is almost nothing for me to do at the helm station
in modern subsim games?"
Well guess what? Not anymore...
This time it actually floats!
In order for our development team to achieve a true and realistic approach to the matter a
standard research procedure is to learn from the works of the veterans of the subject matter (in
this case the subsim genre).
There is NO subsim that actually ever simulated underwater physics! Then the only other
alternative is to research the works of the sibling genre; Aviation Simulators.
Indeed, the sector of aerodynamics and aerodynamic stability is deeply researched by the
simulation development community. But still there is a missing part for a complete simulation of
underwater physics; Hydrostatics.
Behind the scenes look of the submarine along with the locations and status of the various ballast,
trim and compensation tanks. Also both the center of buoyancy and the center of gravity are
Underwater acoustics to the rescue.
The research and development done on the underwater propagation of sound, a topic of
another time and another log book, set up the infrastructure for the development of the surface
and underwater physics.
The ship actually floats due to its ROB (Reserve buoyancy) and dives due to the human
intervention in exchanging the ROB with sea water therefore increasing its displacement.
Standard operational procedures, like flooding and blowing MBTs (Main Ballast Tanks) and
achieving longitudinal stability to the ship by transferring water between the trim tanks is only
just a taste of the tasks that the player has to master in order to achieve a successful transition
of the ship from surfaced to submerged.
What's the connection with flight physics after all?
A modern nuclear submarine, is a two faced beast. When is surfaced it acts like a non sea worthy
ship but when it submerges, it transits into its true element. It becomes fast and agile. At that
particular point the submarine, with the allowance of some disciplined exaggeration, we could
say that it flies through water.
The need to apply some differentiated flight dynamics in combination to the previously
introduced Hydrostatics raised.
When a submarine increases its speed then it is able to change its depth with the use of its
hydrodynamic wings which are called planes. And its in the responsibilities of the Planesmen (the
planes operators) to follow the proper procedures in order to reach the ordered depth given by
the Chief of the Watch.
Like in any surface ship and the submarine is not an exception the course is changed by the
helm which is actually the mechanism that rotates the rudder of the ship in the specified
degrees. That is the responsibility of the Helmsmen, again under the watchful eye of the Chief of
To sum up...
Usually two pairs (fore and aft) of under water wings called planes and at least one rudder are
needed in order for a submarine to achieve under water navigation. That almost sounds like a
plane's behavior, doesn't it?
The various displays on the pilot and co-pilot stations that directly have to do with the control of
Then why so small wings?
Simple, the medium is different. Water and especially sea water is almost 830 times more dense
than air. Due to the foundational axioms of both aerodynamics and in that particular situation
hydrodynamics the more dense the medium is the higher lift force is achieved in the same
surface area of the airfoil or plane.
For those of you who already have an experience in aviation simulators you will not find striking
the fact that every and each submarine provides an operating envelope to the operators called
submarine safety envelope.
Environmental and operational factors like speed, depth, temperature, pressure and salinity will
affect the performance of the planes in MNW, so be extremely careful?
A high speed submarine can reach its depth limit (crush depth) in a matter of seconds.
"What's the matter, Colonel Sandurz? Chicken?"
We know that the whole process explained may sound intimidating and yet it is. Nevertheless
technology always progresses to the benefit of the amateur subsim enthusiast.
Submarines traditionally struggle at the surface in bad weather. And in Modern Naval Warfare we
take no shortcuts as far as physics are concerned.
Virginia class submarines are using much of their sophisticated technology (fly-by-wire, auto-
trimming and auto-hovering) for the purpose of reducing the work load and the number of the
operators. Therefore, the Helmsmen, Planesmen, Chief the Watch and the Diving Officer have
been replaced by two Pilots and in most cases only one is enough to pull through most of the
tasks needed in standard operational procedures.
In retrospect that is not very good for us financially wise. We would sell 4 copies of the
game if we modeled a 688 LA class sub ed.
The player will have the freedom of using any of these technologies to his/her benefit. If
however this still sounds too intimidating to you there is always the AI that you could put the
blame on if during a surveillance operation the Sail/Fin (tower-like structure found on the
topside surface of submarines) will collide against the keel (the bottom-most longitudinal
structural element on a ship) of an enemy destroyer.
Ladies and gentlemen, grab your joysticks!
Till next time...
Stay tune on our forum.