Ship building is the first and most basic skill one must master to do well in this game. This is a general guide to help though some more in-depth ones do exist should you require a more specific design. Also, if you need help, feel free to ask around, there are plenty of very experienced builders on the wiki.
Basics
When building any ship in Battleship Craft that you want to use in GC or for the drills, make sure it is made fully out of armor. The larger 400 mm blocks tend to work best as they take up 6 or 8 times as much space as a 1*1*1 block, thus allowing you to build a far larger ship without going over the percentage bar. Another important factor, particularly for online battles, is speed. Unless you are join for realism, any surface ship should be able to reach speeds in excess of 150 knots. Using the techniques on the Speed Tweaking page, that can easily be achieved.
Stats
Note: tapping a word on the ship's stats screen show information on what that word is (e.g. if you tap Angle a message appears stating that the angle is the degree of the ships after it had sailed forward)
The Stat card that shows the infomation about your ship
Percentage
When constructing or editing a ship, you may notice an icon in the top-left corner with a percentage written on it. This indicator designates how big you can make your ship. This is the biggest limitation laid on the size of your ship. This number can be reduced by using fewer parts, such as large hull blocks/large armored hull blocks; or making hollow structures. Weapons also account for a minor amount of this number, but you should not exceed 80 to 90% before adding weapons. You can place 10 single blocks for each percentage, which is 1,000 total single blocks you can have. Some blocks (ex: cranes) take up more space than normal. All "body" blocks, however only take up 1/10 of a percent so when trying to build a large ship, it is advisable that you use the large armored blocks.
Speed
Speed is affected by weight, water resistance, and number of boilers. Speed can be increased by adding more boilers to your ship. Better or larger boilers have more horsepower(see the boilers page->Engines:)
The maximum achievable speed for most large ships is 194.4 knots, where it appears to hit some barrier. Most surface ships will be able to reach that speed if Speed Tweaking is employed.
Speed is perhaps less important than toughness and strength in the drills, but to compete online, it is advised that you have a ship that is capable of at least 150 knots.
Strength
Strength is the measure of how much damage you can inflict on the enemy, with the combined power of the weapons. The greater the number, the more damage can be inflicted in a given amount of time. Generally, a larger ship should have above 1500 strength; for example, the Yamato, a rather large battleship, has over 2300 strength.
The best method for increasing the strength of a ship would be to install larger guns, such as the 46 cm triple gun and the 38 cm quadruple gun, since they provide multiple powerful rounds per second. However, since strength measures firepower within one second, certain weapons, like the Type 96 25 mm AT/AA, which rapidly fires many rounds per second in the presence of enemy aircraft, can give a false impression of a vessel's true strength.
Many of these more powerful weapons are very large also, and therefore, the easiest way to accommodate them is with a ship with a wide beam or with a fortress, although this might decrease speed and maneuverability. With some effort and a plan, however, it is possible to construct a ship that is both fast and very powerful, with a strength well into the thousands.
Ships that carry planes (hybrids or carriers) also tend to have very high strength ratings as each aircraft has a strength of about 5000. Mines also increase strength by huge amounts.
Toughness/Armor
Both of these contribute to how long your ship can survive. Toughness is essentially the amount of damage a ship/ship part can take before it is destroyed. The higher the toughness level shown in your info chart, the more damage your ship needs to take before the health bar decreases. (For example, a ship with 0 toughness might take a 50% damage from a shot, and if that ship had a higher toughness, they might only take 25% damage from the same shot.) Armor is how much damage is subtracted from each hit. Obviously, the higher the armor number the less damage enemies can inflict. Both of these are increased primarily by adding armor blocks. Those come in 200 mm, 400 mm, and 600 mm types, with each type having a small variety of shapes and sizes. A good armor level should be pretty high, above 300 for a typical ship. But if possible, get that number even higher. Most large ships need a least 750 armor to be competitive in multi-player. Find a balance between armor and speed. A good toughness level for a light battleship would be at least 2500.
Some large ships such as super-battleships, can have toughness ratings exceeding the 6000 mark, and are therefore very hard to sink with anything other than another.
Stability/Angle
Keep track of this at all times when expanding your ship. Stability is how stable your ship is in the water. Keep this number as high as possible, since it ensures the survivability of your ship. The higher the stability number, the more of your HP bar must be taken away for your ship to capsize. A number above 75 stability and a zero-degree angle is recommended. As you've probably noticed, some ships sink before reaching 0% hp. This is due to low stability.
Stability also keeps your ship flat. When your ship is damaged, it may list, or tilt to one side. Higher stability reduces the listing, and thus keeps your guns above water longer or prevents capsizing, or tipping over, of the vessel. Larger ships should therefore have stability exceeding 150.
Angle is the tilt of the ship when it's not moving. If this number is anything but zero degrees, your ship will be more likely to capsize. It's not that difficult to keep the angle 0 degrees, but make sure it is before exiting the dock. When building asymmetrical ships such as aircraft carriers, one can use ballasts or heavy ballasts to counteract weight issues.
Types
As of version 1.6.1, there are an infinite combination of naval vessels. Some vessels are more common than others. Depending on your play style, you can choose which one you want to build. Stability is always an emphasis on any ship type. The listings only regard performance- armaments are left to their respective pages. Generally, when aiming to complete the game, one should lean towards the larger "battleship killers", though small, nippy boats can still be effective in GC. Step by step building guides can be found for many of these ships on YouTube.
Frigates/Fast Boats
These ships do not care about armor or toughness, since they rely on speed, small size and maneuverability to avoid shots. While armor may be helpful for taking an occasional lucky hit, they generally do not take sustained fire well. Thus, the emphasis should be on speed and maneuverability. Catamaran hulls are recommended as stability is important when making tight, erratic maneuvers.
These vessels are often the smallest functional combat vessels in the game. This attribute makes them very difficult to hit. With proper Speed Tweaking though, you can find a balance of good speed and reasonable armor. Speed should normally be around the 195 knot mark for an effective fast boat.
Destroyer
Similar to the Frigates/Fast Boats, only that these ships are slightly larger and trade some maneuverability for some firepower. However, mono-hulls are desired due to their ease of upgrading. Some armoring is necessary for increased durability.
Cruisers (Battlecruisers)
Apply a balance between armor and mobility, since cruisers are designed to be able to destroy smaller ships easily through armor and toughness and larger battleship through speed and maneuverability. Their larger size means that hits are more likely, but maneuverability is still an option. good armor and speed are necessary for survival.
Battleship/Battleship Killer
Emphasize armor and toughness over speed and mobility. However, do not be afraid to sacrifice a little armor for much greater mobility. Large 400 mm Lightweight and 3 x 2 x 1 400 mm Lightweight is recommended for optimum performance. With correct Speed Tweaking, even the largest battleship killers can reach great speeds, though maneuverability will never be great.
Fortresses
Forget about mobility in general. Emphasize armor and toughness. Stability will come naturally, since fortresses are inherently stable warships. However, if it is possible, employ some limited mobility for positioning. Also, ensure that your armament is spread evenly and facing in all directions as your opponent (in GC at least) will out- maneuver you with ease.
Rams
Rams will require an unusual combination of armor, speed, maneuverability and toughness. Stability is essential to prevent capsizing after an attack. A small, catamaran design is therefore recommended. Some point blank weapons should be fitted such as torpedoes, depth charges and, if possible, mines.
Monitors
Speed and maneuverability should be reasonable, given the ship's comparatively small size. Firepower is essential, usually of near-battleship caliber. Stability is also important, since large cannons will be difficult to balance. Monitors are best when decoration is spartan at most.
Aircraft Carriers
High mobility will be necessary to evade heavy guns. Armoring should be as good as possible, in case of hits. In the case of hull conversions, the speed, mobility and toughness would mimic the ship it was built on. Speed is the most important statistic for carriers if you are the type to run, but toughness is very important if you want to absorb the blows. The angle can tend to change from zero when adding islands (see the angle paragraph above).
Submarines
Since the submarine will often lie literally beneath the damage-dealing guns and ASW weapons are lethal in one-shot, submarine design should focus on speed and maneuverability. A good guide to follow for submarine building is SWC's MK.1 sub on YouTube The most important thing when building subs is patience. It is a very fiddly process, but becomes easier with experience. Also, your sub must have a density of 1.0.