Submarine Warfare

Sub building is difficult, complex and expensive. I've decided to share one of my more stable designs with those of you who would like to learn how to build subs.  The Ardent is my favourite submarine and I've had heaps of fun with it. It can 3 star all levels (except night battle 3 so far) and is competitive online. 

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Submarine Warfare


The Beginner's Ardent

A very good starter sub for those who want to start building their own subs. It's a bit faster than the stock submarine in the game, equally easy to use and packs the same punch. It's also very well suited to modifications which I have included below to show you what you can get. 

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Beginner's Ardent at Max cruise - had leveled out

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Blueman's Dog's U-boat At max Cruise - has leveled out. A bit Slower

Materials and Cost

  1. You will need at least 2 torpedoes to be effective, 4 for this demonstration and 6 for the ultimate variant. you can scale this number up very easily. 
  2. You will need 5 Angled Boilers
  3. About 150 angled 40mm lightweght armour blocks
  4. 11 large flat 40mm lightweight armour blocks

Total cost this version: About 46 000 without torpedoes, 330 000 with 4 torpedoes , so about 100 000 cheaper than the stock u-boat (only 3/4 price).

More advanced versions are even cheaper (use fewer angled blocks, so about 10k cheaper)

How to Build

21 steps (and 3 appendices) on how to build a Basic Beginner's Sub

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Step 1: Heavy Ballast

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Step 2: 40mm Lightweight armour

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Step 3: More 40mm lightweight armour

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Step 5: 60mm armour with a single strip of Heavy Ballast in the centre.

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Step 6: 5 Angled boilers

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Step 7: 60mm armour and a rudder

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Step 8: 40mm lightweight armour

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Step 9: 4 torpedoes

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Step 10: 60mm armour

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Step 11: shaped 40mm lightweight armour

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Step 12: 60mm armour

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Step 13: 40mm lightweight armour (shaped)

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Step 14: 40mm armour

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Step 16: 60 mm armour

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Step 17: Sloped 40mm armour

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Step 18: 3/2/1 40mm lightweight armour slabs

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Step 19: 40cm armour and sloped 40cm lightweight armour

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Step 20: 60cm lightweight armour and sloped 40cm armour

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Step21. Depth Guages

Note 1: At this point is NOT ready to use! 

The Three blocks above the torpedo tubes have to be weighted with a 40mm, heavy balast, 40mm Sandwich, or alternatively swapped out for a torpedo tube. I did not show this in the guide.

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Blue: 40cm Armour Red: Heavy Ballast

Note 2: Notice the 2 propellors are added. (step 7 and step 13)

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Beginner's Ardent Prop Arrangement

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Ardent, and Fast Ardent Prop Arrangements

Note 3:

Notice the rudder and angled block at the back. (Rudder step 10, angled block step 11) 

After that, have fun.

How to Use

Full throttle:  Cruising

Dives to a cruising depth and reaches its max level speed of 76.5 kts. A half rudder turn will keep it practically level, a 75% rudder turn will have it decend slowly and a full rudder turn will have it descend moderately. Straightening out the rudder will allow it to come back up to cruising depth slowly. Rapid rudder changes will not roll it over, but it will moderately descend if using full rudder in changes. 

3/4 Throttle: Gentle Ascent and Maximum turning

At this speed you will be able to make maximum turns while ascending slowly. If you keep the rudder straight you will ascend lightly at a speed of 68.3 kts. 

1/2 Throttle: Rapid Ascent

Regardless of Rudder or what yu are doing, this speed setting will bring you to the surface rapidly. You will then cruise rapidly at the surface at around 60Kts

0 Throttle - Bob to the Surface

You won't ever need to use this in combat. 

-1/4 Reverse: Gentle Ascent

This setting will bring you to the surface regardless of rudder setting. You will cruise at the surfcae at 48kts at this setting.

-1/2 Reverse: Gentle descent

You will be able to gradually descent at this speed if you use full rudder. Straightening out the rudder will keep you close to level cruise (but in a gradual decent) at a speed of 58kts. By switching back and forth slowly between -1/2 and -1/4 throttle you can manuever in reverse just as easily as if you were going forward. 

-3/4 Reverse: Dive

You will seldom use this setting, unless you acccidentally set it instead of -100 Throttle. Throws you into a reverse dive at 69kts. You will descent quickly, but controllably. Switch back to -1/4 after a while to prevent diving through crushing depth.

-100% Reverse:  Reverse Dive / Crazy Ivan

At this setting you will dive backwards. This is a controllable dive and you can easily return to the surface by reducing throttle. Make sure the rudder is straight. 76.7kt speed while going backwards. With practice and the correct technique you can go from full speed forwards to full speed backwards, to full speed forwards again without sinking or surfacing. See Crazy Ivan for more advanced manuevers. 

Advanced Manuevers

Crazy Ivan

During the cold war US submarines used to sneak up on russian submarines to gain information on their tactics and stats. Some russian (Soviet) submarine captains used a tactic to try and find the american subs. What they would do is suddenly reverse throttle rapidly and make a massive turn to rapidly change direction. They hoped that if there was any american submarine was close enough to them, the american would also have to rapidly change thottle and rudder to avoid colliding. The Soviet captains hoped that this would reveal the American sub as it noisily manuevered to avoid collission, or at the very least scare the crew a lot. The Americans called this move the "Crazy Ivan" after the american colloquial term for a russian (IVAN)

The Beginner's Ardent has sufficiently suitable hydrodynamics to allow you to perform a crazy Ivan without popping to the surface or diving into the crash depths.

How to:

While traveling in the green depth zone reverse throttle completely. The Ardent will remain underwater and accelerate backwards up to 76kts. You can stop the descent by applying -1/4 power and then travel underwater in reverse indefinately by switching between this and -1/2 to control your depth wile cruisng and turning.

To return to full forward motion descend to the red zone. Go to full forward throttle and make a maximum rudder turn of any direction. The Beginner's Ardent will rise to the green depths, maybe the aqua and then gradually start descending again. Straighten the rudder to return to cruising settings.

You can perform this manuever underwater to help escape enemy destroyers with depth charges, or to quickly reverse course for another torpedo shot on an enemy surface unit that you have just passed. Practice this before trying this online.    col·lo·qui·al col·lo·qui·al


Physics of Submarines

Submarines are  normaly finely tuned in regards to power, weight and balance, so damage that a normal ship would not notice would either cause a sub to pop to the surface or to sink to the bottom below the lethal zone (crush depth). Their high density, low stability and the distribution of the armour means that they cannot take much damage at all before they sink, so surfacing is just as dangerous as dropping into the crush depth.  For that reason, submarines rely on 1 thing to keep them safe: depth.  A deep submarine is a safe submarine. If you are shallow some lucky shots can still damage you and dive bombers can kill you. At depth, you are no longer hunted, but are the hunter.

The thing that makes a submarine competiitive and scary to the opponent is the underwater torpedo. It's a fast 92kt weapon that can disable even the best surface vessel with a single salvo. Unfortunately the torpedo is slow and short ranged, so the next important thing a good submarine needs is speed. The faster you are, the easier you can manage to get close to the enemy and fire the torpedoes. Submarines have more area in contact with water and are heavier for any given size than their surface counterparts. This makes them approximately half the speed of a similarly well designed surface ship. A well designed sub should reach at leaast 70kts underwater.

However speed comes with a cost. Submarines have to carefully control their speed at all times to keep at a constant depth in turns. This means that they generally are not as agile as surface vessels. The faster the sub, the less stable it is, the harder it is to keep at a set depth and the more difficult it is to control.

This means that the next most important thing for a sub is stability. This is done though perfect weight distribution and good hydrodynamics.

An example of the difference is that of the Beginner's Ardent anf the Super Fast Ardent Mk 1. The Super Fast is a good 30kts faster, but is much more difficult to control. It can probably be modified to go faster, up to about 130kts, but then it would be impossible to use safely in combat. The Beginner's Ardent on the other hand is a very smooth handling ship, but ideally needs another 10-15kts to be able to take on the faster enemies out there.  Luckily, there are 5 different Ardent variants for you to chose from based on your level of skill and your needs, each with a slightly diffrent compromise of speed and stability. Explore the differences to see what you look for in a good submarine.

How the Ardent Works

The hull is slightly heavier at the nose and the nose's shape is designed to quickly push the sub underwater as the sub gains speed. Combined with neutral bouyancy, this means the sub dives rapidly.  However, the shape, positioning and size of the conning tower means that the ship suddenly gets pushed up when the conning tower is finally underwater, bringing the ship to the surface. 

At low speeds this hydrodynamic force is more than that of the nose, causing the sub to rise gradually.

At high speeds the hydrodynamics of the nose is now strong enough to exactly equal that of the conning tower allowing the ship to remain at the same depth at max speed (or ascend/descend ever so slightly if balance is not exactly right). Minor Tweaks in weigh distribution will allow the ardent to exactly level off at a particular depth. I have built the Beginner's Ardent to just ever so slightly rise at max speed so that you can make gentle turns underwater without descending.

The reason I had to do this is that in a turn the ship rolls slighty. This means that the lifting force is angled, and the slightly heavier nose pulls the ship down a bit because its no longer exactly countered by the lift pulling directly upwards. A way around this is to reduce the weight of the nose and rely solely on differing hydrodynamics, but practically this is not possible. Therefore in maximum turns, power should be reduced slightly to allow the ship to remain level in the turn.

Changes to the More Advanced Ardents

The Ardent, Fast Ardent and Super Fast Ardent Mk.1 have less hydrodynamic force pushing the nose underwater, and more weight on the nose in the form of 4 Harpoon missile launchers. This means that they sink gradually at about 50% power, but return to the surface at 100% power. It also means that maximum turns are done at 75% or 100% power to keep it level, and that they cruise underwater at about 50-75% power. These ships will comfortably break 100kts when they surface, which is ideal for pursuit, but they will have to dive once they get near enough to be shot at. 


Throttle forward fully to dive to cruising depth and speed. 

Steam straight to the enemy vessel, taking note of enemy weapons such as depth charges, bombers and 5cm guns. Don't get too close to the surface.    When making turns, reduce speed slightly to allow ship to remain constant depth. When you level out, add full throttle again to avoid popping to surface. 

Aim slightly ahead of ship and fire half of your torpedoes. Enemy will try to avoid them, so turn sharply and fire other half. 

Extend out and come around slowly and carefully.

Take your time, submarine warfare is slower than surface warfare and is a patient game of chess where the first person to make a mistake dies. Out- patience your opponent. The last thing you want to do is accidentally pop to the surface or you WILL die. 


  1. Lead the enemy
  2. Fire half your torpedoes, then turn sharply to fire seconds half.
  3. Turn carefully
  4. Take your time
  5. Think 4 dimentially Marty

Other Ardent Varients


Sub extended to fit 6 angled trubines. Tail reshaped for greater speed. Conning tower moved to change hydrodynamics. 4 Missile Launchers added to ballance out Conning tower move. 

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Ardent Online

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Ardent Red is where torpedos or 40cm/HBallast/40cm sandwiches go. White is where Harpoons are mounted on top.

Fast Ardent

Almost the same as Ardent, but most of the angled 40mm lightweight blocks on the nose have been removed except for the ones along the centreline to give a 10 kt faster sub.

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Fast Ardent Red is space left for torpedoes or ballast, white is where the Harpoons go.

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Fast Ardent fighting online. Shortly after this I lost patience and accidentally rammed my opponent.

Super Fast Ardent Mk 1

Nose completely reshaped. 10 kt faster than fast Ardent. Waiting on 8 turbines to replace 6 angled boilers. Conning tower clipped to half height to modify the hydrodynamics. 

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Super Fast Ardent Faster than the beginner's ardent in a turn and at 50% throttle

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Super Fast Ardent. Heavily modified Ardent that can keep up with many surface ships.

Cheap Ardent

All 40cm lightweight blocks, save for top 3x2s, replaced by hull, step 1&2 erased when finished, heavy ballast substituted for step 3 on sides. PROPELLERS MUST BE PLACED ON THE BOTTOM WITH POLES FACING DOWNWARD. 2 placed near back, 1 placed 3 blocks from front. Speed decreased somewhat, other than that a wondeful sub for 170,000.


My version of the Ardent, changed to be about half price due to not using lightweight blocks.



 Beginner's Ardent  Maximum TorpedoConcept 

An experiment to see how many torpedoes can be crammed into the ardent design. Still playing around with ballance issues. I'll keep you informed of progress. 

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18 torpedoes on this one and counting.

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Experimentation continues...


Modification Guide


If you can't afford 4 torpedoes, you can rebalance the ship, by replaceing the torpedo tube with a 40mm, heavy ballast, 40mm sandwich. I use 6 Tubes on the standard sub. In the future I plan to modify the planform to have all of them firing up, rather than to the sides. 


I like these on my subs. Remember that they are heavy and slow the sub down by about 5 kts. You have to rebalance the sub. Be careful using these as you have to surface to fire them, making you vulnerable. Time the moment carefully. Or fire them all early in the hopes of shooting down some aircraft.


These are a fun addition with little downsides, but difficult to use effectively.

Depth Charges

When an enemy sub battles you, you are at a stalemate. The only way to get him is to surface quickly, deploy charges and then dive again. Unless he is an idiot and surfaces, in which case, torpedo him like normal. 

Other weapons

Don't bother. Not worth upsetting the balanced design. You are not fast enough to use the 5" Mk45 effectively like a destroyer would, or tough enough to use 40/38/46cm guns like a battleship. Leave surface warfare to the surface vessels. 

Turbines/More Boilers

2 boilers produce one and a half times the power of 1 boiler. Six boilers produce twice the power of one boiler. As you can see there are diminishing returns. Don't bother with more than six boilers. Rather upgrade the type of boiler instead. Remember to rebalance. 

Angled blocks

These slow the ship down so feel free to dump these. Faster subs are WAY trickier to handle, and doing this to the Beginners ardent to make it go faster actually reverses the way the ship acts at high speed. Play around with this, but back up your designs. The Ardent is cheap enough to make multiple copies. 


Add your questions here so that I can modify the ship/page.


Feel free to improve the quality of this page, or to add or post pics of your own versions of the Ardent. Modifications to the physics and how to use will be especially appreciated.

Hope you have fun

Spite Out

Action Shots:

Just because I think the Ardent is a pretty submarine