Before you begin to design a warship or tank, you have to ask yourself some crucial questions.
1. Whats the problem? Or, what do I need?
This is arguably the most important question, as the problem defines what you'll be making. For example, in one of my conquest games, I had a nation on a small island, that no one dared invading. Why? Because this island had several nests of dragons, as well as the Elder Dragon. This was a major problem.
2. How can this be solved?
This is something that is crucial because it influences the actual design. Taking my dragon problem into account, I believed that the solution would be several flak guns on the roof of the ship, along
with heavy armor.
3. Whats within my budget?
When building any type of ship in this game, you NEED to take your budget into account. If you only have a few provinces, and a few thousand saved up, don't expect to be able to construct anything too large. For example, if you have $3000 gold, and $100 income, would it be a wise choice to save up for a ship with $10,000 and a $200 maintenance? Put simply, no. You could save up, true, but your going about this the wrong way. To begin with, that would be absolutely detrimental to your country. Once constructed, the maintenance would absolutely drive you into debt, and when that happens, you can't move your ships. Eventually, they'll betray you. In addition to this, putting all your hopes on one mere ship is absolutely foolish. There are very few ships that can serve as a One-Ship Navy.
4. Whats too unrealistic?
In my case with the dragons, I was desperate to get some sort of wonder weapon out there. I wanted it to have the best metal armor available, and I wanted it to have enough guns on it to knock dragons out of the sky, AND serve as some sort of general purpose ship. But this was extremely unrealistic. Why? Because at the time, I believed the only way to kill a dragon was with lots of cannon or with lots of flak. So when designing my ship, I had to choose one or the other. I had to allocate resources, money, time, and other factors (other factors like weight of the ship, coal storage, ammo storage, water availability, etc...) into the the final design. You MUST make a ship with realistic expectations, budget, and availability (don't design something you can't build).

This particular ship was such a failure, I can't even remember the name. This was the first anti-dragon type ship I made, and by all means, it was unrealistic. I underestimated the power of dragons, and as such, I wasted time and resources.

This ship, was the Thor Class anti-dragon type ship. It was upwards of $8000, and it utilized lots of guns, and heavy armor. For sure, this thing would work right? Wrong. This was especially a devastating blow, as I not only used some lessons from the previous failure, but it was expensive. Put simply, the dragons ripped through it in a matter of seconds. The dragons flew into the blind-spots and roasted it. Now your aware why is was a failure, but why was it unrealistic? Well by this point, I knew that the AI aims for your weak-spots. In addition, I should've known that the dragons wouldn't just sit above it.
5. Could I bet success on this vehicle?
If you can look at something and say, "I think it'll do alright", then you've run into a problem. Don't waste money and time on constructing and designing junk. If you think you could improve, then do what you can within the boundaries. If your still unsure, instead test it in simulated combat. Make a few test ships and buildings, and test your new creation against those. Do it by tier. Test it against progressively harder structures or ships. If it can't hold up to what you've set the standard to, its useless, and needs to be reworked, or something new must be made. For example, if you make a ship that is expected to at least take on pirate ships but can't then it can't serve in its expected capacity and its therefore useless. Either rework it, design something new, refit it, or allocate it to some other duty.
The only good junk in this game is the junk you can learn from. Despite my numerous failures, they proved to be extremely beneficial in the long run. Without my failures, I wouldn't have been able to produce the good designs I have now.


If a design didn't work, then ask yourself these questions before reworking, or redesigning.
1. Why did it fail?
If something goes wrong, you NEED to know what the problem was with the creation. You can't fix it or make something new to counter the problem if you don't know what it is. During combat, study the ship. Check the outside, and the inside. You NEED to know where the problem lies. Is the ammo or coal caught on fire, and does it eventually blow the whole ship apart? If so, redesign with water closer to the source. Ships should only explode if they are under intense fighting. If they catch fire and blow up, you've got yourself a problem.

This is the Tanya Degurechaff Cruiser. I bet on this thing being fairly successful; at the time. Looking back, and after learning my mistakes, this thing was doomed for failure.
I'll touch on it later, but the problems were:
A. Bridge was exposed to open elements.
B. Weak power output, couldn't fly very high or fast.
C. If the bottom hull was shot a few times, the small suspendium chambers would explode in a chain reaction, and the whole belly would explode and the ship would not only take severe damage, but it would be completely knocked out of the sky.
D. Effective only against weaker ships. It was designed as a general purpose vessel, but it couldn't take on heavy land defenses, or any ships equal to, or better than it by any means. Even if outclassed, it should've been able to do some damage, but that wasn't the case.

2. Does it need to be redone from scratch, or could I simply alter the design?

This is the Queen Bee class carrier. Principle was to have a lot of small aircraft. Unfortunately, they were useless, and the ship was designed terribly. The coal was on the whole other side of the ship from where the suspendium engine and chamber were. Making it prone to crashing after just a few seconds. Lesson learned? Keep coal close at hand for engines and lift chambers.
If a ship fails, you need to be sure if it was an utter failure, and if just restarting it would be easier, or if it could just be altered for improvement.
3. How many problems are there, and where are they?
After analyzing the problems, you need to know where they are specifically. For example, in Tanya Degurechaff class cruisers, I had to pay attention to where they tended to catch fire. It was primarily just one problem, and it was at the belly.
4. Is the ship still similar or does it need to be renamed after its alterations? And, is it worth it?
After you redesign your ship, is it still roughly the same as it used to be? If not, rename the ship. Save it under a new name so you could build more if need be. Also ask, is it still worth building it? Will it be better than the original, and is it still within acceptable boundaries?
5. What are the lessons learned for the future?
Whether you apply your lessons from failure to this design or into future designs, you need to understand what went wrong, and what NOT to do.

Ok, I know your eager to hop into Airships and start building, but I'm not quite finished, in fact I'm far from it.
When building anything in this game, you have to take factors into account. Before and after you assess your problem, before, during, and after designing, after prototyping, and even after some time being used in combat.
Some factors are, but not limited to:
1. Time it takes to build vehicle (the bigger and more expensive, the longer the wait time)
2. The amount of money you have currently saved, your current income, and how expensive the vehicle is.
3. Complexity of the vehicle.
4. Needs and expectations
5. Onboard factors (amount of ammo, coal, personnel, gun placement, accessibility, water, lift power, propulsion power, overall stability)
6. Usefulness
7. Pros and Cons
8. Personal Touches; the aesthetically pleasing look of the vehicle

In regards to construction before, during, and after, ask more questions.
a. Did it meet criteria?
b. Am I satisfied with its performance? Is it useful enough?
c. Comfortable with price?

To begin, you need to take into account the build time. If you plan on building large battlecruisers or larger, you're gonna a small defense fleet on standby. Take my word for it, you'll need it. The AI has a habit of attacking when your most vulnerable.
Second, save at least a quarter of your treasury in case the unexpected happens, like you suddenly going into debt. In addition, be sure that the maintenance cost of everything doesn't outweigh your income.
Thirdly, the complexity of any vehicle makes it hard. During design, refitting, or even after. Make it as simple as you can. It makes the ship more efficient, and makes updating ships easier.
Fourth, ALWAYS take the needs and expectations of the vehicle into account. For example, when I needed a cheap tank early game, I decided to go for whatever was cost efficient. I clipped off whatever I didn't need to meet my goal, my expectation. Which, my need, my expectation, was something cheap yet decently effective for its price.

Which in turn led to the designing and creation of this nice little thing. This is the Beetle Mk2A. The whole purpose of the Beetle was to be expendable and cheap, so that I could quickly invade early game. That, or be used to buy me more time in case an enemy was approaching my borders. Either way, for being $500-$800, this tank was an absolute revolutionary vehicle for its time.
When designing it, I had to take into account cost effectiveness. To keep it cheap, I had to go with the cheapest armor that was useful, and use the least amount of modules. What I ended up with, was a miniscule amount of coal and ammo, which was just barely enough to keep it fighting for the duration of the battle, along with one cannon and one rifle. These little things were absolutely amazing early game. However, when it got Mid-Late game, that changed; unpredictably. My point is, your needs for a vehicle must be accomplished to meet your goals. And my need at this point in time was something cheap and expendable to be used for rapid early game expansion. In this respect, this tank was a massive success.
Fifthly, take into account your onboard factors. During design and after. Keep asking, "is this enough?" If for whatever reason it isn't, do a quick redesign. You'd be surprised at how much can be improved with just a little bit of tinkering. Especially when you know how to improve after the vehicle has battle experience.
Sixth, always question its usefulness. Using my Beetle tank example, it was extremely useful early game. I got what I needed, and more. My economy was great. However, then the enemy brought out heavier vehicles, and my little Beetles never stood a chance. And thus ended the era of my light tanks. After they started getting shredded, I had to question their usefulness, then adapt and redesign a new tank after realizing that they were no longer as useful.
Seventh, before, during, and after combat experience, weigh the pros and cons of the vehicle. Sometimes you have to intentionally have a downside, so that you can have an upside with a vehicle. Just weigh if the good is better than the bad. This goes hand in hand with usefulness. Because you want to weigh the pros and cons at all times. If the cons ever outweigh the pros, then you need something else.
Eighth, always decide if you want a personal touch or not. Personally, I don't add much in terms of aesthetics, but I can't help but do it for successful vehicles. Trust me, seeing a glorious ship with decked out roundels and paint is truly a beautiful sight in this game.

For example, what are some pros and cons of this vehicle? What are some other factors that are important?
Pros: Its got firepower, and good armor, its not too expensive, reliable, decent amount of ammo.
Cons: Slow fire rate, slow movement speed, has difficulty climbing hills at times, vulnerable to bombers, and barely enough coal.

Before I begin, lemme lay down some rules.
1. Like I've said a lot before, STAY WITHIN YOUR LIMITS. Check this frequently.
2. If you can't have something, MAKE A CHOICE. If you don't want to make a choice, then adapt. For example, you want a fire point and a ammo cache but you don't have space? If the ammo is were necessary, then choose fire extinguishers to have room.
3. ALWAYS check your overlays. Make sure your crew has at least 2 pathways to get to something, unless if the 1 pathway is surrounded by heavy armor and other modules. Make sure water can get to everything (meaning make sure the water is close to all fire sources). Make sure every gun has at least a little bit of ammo, and make sure that the crew doesn't have to go far to get ammo. Put coal close to propulsion and lift systems.
For example, my Queen Bee class carrier. Because the coal wasn't close to the engines, it fell out of the sky, and because it took too long to get coal, it couldn't regain flight. Bad design, don't do this!
4. DON'T DO MORE THAN NECESSARY. You don't need more than you can shoot, nor do you need a bigger explosion on board your ship.
I used to have this problem, big time. Guys, your ships will start every battle with full supply. So don't pack so much resources that space and money is wasted, its not like real life where you have to resupply after every battle. You only have to account for ONE BATTLE worth of supplies. So for example, my Beetle Tank. It had just barely enough coal to move from one side of the map to the other, and just barely enough ammo to meet its short life expectancy in battle . Most of the time, a tank only needs 100 rounds, not 300. Most of the time a ship only needs 300-400 rounds. Nothing more. More often than not, the ship won't even use all its ammo, and in addition to this, it puts the ship in more danger, as it serves as an explosive. This is bad in the long run. Yes, you'll have long-running battles, but this is only about 40% of the time, when you don't have a large fleet, or if they have more ships than you expected.
5. ADAPT to unexpected changes. This goes hand in hand with Rule 2, or if your redesigning after something went wrong, or if its a failure.
6. DON'T LEAN on specialty ships. You want more general purpose than you do specialty. If for whatever reason you lose your fleet or most of your general-purpose ships, your specialty ship can't do much. Very few specialty ships serve well in general combat in addition to their specialty.
7. In addition to Rule 6, DON'T GIVE SPECIALTY SHIPS TOO MUCH. For example, if you make a Kamikaze ship, you want just good enough armor to get to its target. But you don't want armor to be too thick, or it won't explode unless they really shoot at it. You also won't need guns, because guess what? You won't be using them.

So to begin, I'm going to detail my design process. Not only do I follow these rules, but I follow a very strict design process. My design philosophy is to construct quality vehicles mid-late game, and cheap somewhat effective vehicles early game.
1. Have a grasp on the class of ship you want, and the specifications it needs to meet. As such, choose the RIGHT TYPE OF ARMOR FOR THE RIGHT TYPE OF SHIP.
This is arguably one of my most important moves of the design process, because this is what is my main limiting factor in terms of weight, and how far I go. For example, if I'm designing a heavy cruiser or above, I'm gonna be using the highest tier of metal armor. As such, I can expect to be limited in speed and ceiling height. This step is important, because it will affect the rest of the design. Trust me, there is NOTHING worse, than designing a ship, sticking some heavy armor on it, and suddenly it can't fly. Its the worse feeling in the world when you realize you have to redesign the entire ship.
2. Decide on either LENGTH OR WIDTH.
Now this is also very important. Long ships tend to be more aesthetically pleasing, however, they tend to be harder to work with. With longer ships, in order to stay within boundaries, you have to squeeze things in tight spaces. Whereas with wider ships you have more freedom when it comes to fitting in modules. Long ships also tend to have less pathways, making them easier to destroy (this is why I spread out guns along the entire ship in my newer designs. So I don't lose all my guns from one battery). Most of the time, length-based ships are harder to work with.
3. Place down guns, then critical modules. Keep the bridge under the surface.
When building a ship, the first thing I do is place down the guns I want. Once I do this, I can place down ammo, then move on and start placing down other critical modules where I can fit them.
Note: Keep your bridge OFF THE SURFACE. There is nothing more useless than a ship that can't move in battle. Your enemies can work around you and rip you to pieces, and use your weaknesses to their advantage, no matter how impressive it is. Without a bridge, its just a hunk of metal.
4. Make sure every gun has some ammo. In addition to this, spread guns out. You don't want to lose them all in one critical moment.
5. Check overlays, and make sure your within acceptable parameters.
6. Place suspendium lift chambers in the center (if possible).
In a lot of my older designs, I didn't follow this rule. But I've learned that placing the lift in the center of the ship makes it a lot harder to shoot the ship out of the sky. Enemies will target the high-explosion areas, and the first thing they usually aim for is lift. If you put lift in the center, it makes it a lot harder to destroy them, because they are surrounded by other modules.
7. To top it all off, put down quarters, berths, and aesthetics. Quarters while necessary, if they get destroyed, it doesn't really matter. Just place them where they don't really matter, and place them down only after you have the critical stuff down. If you don't have space, use berths; their pretty useful. In addition to this, if you want it to look good, top it off with some good ole' paint and decor.

This section is going to be short.
If you make a new model ship, then DON'T immediately construct it. Bad idea. You may think it will do well, but it may not. So instead, test it in the combat mode in the main menu. This will give you critical pointers for improvement should it not function as expected.
In addition to this, if you pay attention to my designs, you may notice how I label things. For example, Mk1A, Mk1B, Mk1C, Mk2A, etc.
For simplicity, "Mk" stands for model. The number, stands for that specific model, and the number only every changes if the vehicle is generally the same, yet has undergone significant changes. The letter at the end, stands for variance. Variance, is the same model, yet varies from the particular mark in a very small way.
So for example, the Beetle Tank Mk1A.

This is the Beetle Tank Mk1A, and was a failure, because it couldn't climb hills effectively.
So I made the Beetle Tank Mk2A.

What makes the Mk2A different? Well put simply, there was a SIGNIFICANT change. This change was the propulsion systems. It not only changed the look of the vehicle, but it gave it better efficiency. If it changes the look or usefulness of the vehicle considerably, it is a significant change.
Ok, but lets say we made a model called the Mk2B. What makes it different from the 2A? Pretty simple. The 2B is the same in almost every single respect to the 2A. It is essentially the same vehicle, with a slight variation. These slight variations can considerably change the efficiency or power of the vehicle. However, they are variations because they don't significantly change the look, or are generally based on the same chassis. For example, some ships have the same chassis but have different weapon load-outs. This would be a variant, because its BASED ON THE SAME VEHICLE.
An example could be my beetle tank series.

When I was having my dragon problem, one of the things I did a lot of, was experimenting. I did whatever I could think of and just couldn't figure anything out that could work to deal with my dragon problem.
All I knew that I needed, was something that could deal a lot of damage, very quickly.
But there is nothing out in the world that could shoot quickly and do tons of damage. But I kept thinking, and I decided to take a lesson from the AI and try rockets. Extremely inaccurate. Yet powerful and quick to reload.
So I decided to mix those with cannon and guess what? While outdated now, I ended up getting one of the most powerful ships ever constructed in one of my games.
It was the Fortressor Series.

Some Advice:
1. Don't use firepoints or corridors (ladder or regular). Use fire extinguishers. More cost efficient, saves space, and they still get the job done. Especially if you have a lot of corridors, trust me, you'll have plenty of water. One of the few cons, is that it slows down your crew, but that means it could also slow down the enemy.
2. Use shapes on your builds to make them aesthetically pleasing.
3. When building a ship, always keep your goal in mind and stay within your limits (I have a problem with this, and my initially planned heavy cruisers end up being battleships, and my light cruisers always end up being heavy cruisers. I have a problem with wanting to add more and more firepower).
4. Again, try the unexpected. You'd be surprised about how things may end up working.
5. Shapes you add to your ship, for aesthetic reasons, can actually be beneficial for your ship. They can sometimes give it a bit more protection.
6. In addition to this, Keels can be beneficial as well. Put them on the bottom of your ship, and not only will they add stability, but they can protect the underbelly of your ship, making it harder to hit modules near the bottom or at the edge of the hull.
7. CHECK YOUR OVERLAYS
8. Add planes if you can to give your ships a bit more of an edge. However, don't rely on fighters (biplanes and triplanes), or hussars. They are only good at taking out other aircraft, which isn't something you need to worry about most of the time. Don't rely on torpedo bombers either. Yes they do a good deal of damage, but they have to restock after every bomb, and are too slow. Easy to shoot down, and take too long to be useful. Use bombers. They fly high, and consistently deal decent damage.

When constructing a whole fleet, make sure you have diversity. Though this doesn't mean to have too many specialty ships.
To begin, percents.
You want about 70% of your ships to be cruisers. Of this, you want about 20% light cruisers so that they can fly behind the enemy and shoot them. 30% of this you want to be about medium to heavy cruisers. Then 20% you want for battleships. The last 30% you want to be either specialty ships like bombers, or carriers.
Utilize all this well. Use every ship to its fullest potential, and keep your weaknesses covered. Every ship has at least one; even all-rounders.

First of the Tiger Tank series. Lesson learned? Not enough ammo, or firepower.

My first bomber carrier was on land. Terrible. Much less useful than an airborne carrier, and easier to destroy when on land. Only benefit? Cheaper than airborne carriers. Lesson learned? Land carriers aren't as good as airborne ones.

First of the Beetle tanks. Couldn't climb hills. Everything else was fine. Lesson learned? Small tracks aren't good in some circumstances.

First airborne carrier. Was a disaster, as it fell out of the sky when the whole balloon was popped. Easily destroyed and rendered useless. Lesson learned? Don't use balloons for airborne carriers.

Was based of the hull of the relatively useful Beetle cruiser series. However, the Beetle bomber while good in theory, just wasn't useful. Easily destroyed from low-altitude flight. Lesson learned? Not an efficient bomber design.

Tanya Degurechaff cruiser. Belly was weak to fire, and was easy to destroy if the weak spot was shot. Lesson learned? AI targets lift and propulsion. Move explosives to the center of the ship, or where they aren't as exposed.

Dragons flew behind the weakspot. Lessons learned? Dragons will use the weak-spots.

Queen Bee class. Crashed within a few seconds. Lessons learned? Put coal close to lift and propulsion systems.

First of the Pestilence battleship series. Lessons learned? Put your bridge inside the ship, not outside it.

Thor anti-dragon class. Easily destroyed by dragons. Lesson learned? Dragons don't sit still.

These are just a few of my failures. But please take note of mine as well as your own. All your failures failed for a reason, and you must learn from them in order to make better designs.

Use them. They can give you a lot of power. I recommend Whitefox's and DocPeabody's especially.