The Ironclad age (the 1890 start in RTW3) has some marked differences from the time of the First World War, and brings its own interesting tactical challenges.
Combat ranges tend to be short. Gun sights and fire control are relatively primitive. The heavy guns that are in existence might sem impressive, some of them at 13 inches of calibre. However, these guns have short barrels with low ranges and are very slow to reload. This is denoted in game by a gun quality -2 or -3. They fire at less than one round per minute, and have poor accuracy to boot. Armor penetration is low, so even if they do manage to hit something, it is uncertain if they will cause much damage. This means that medium guns are relatively more important. They have better rate of fire compared to the heavy guns of the era, and even if they do not penetrate armor, they can wreck superstructure and cause fires. This is the reason ships from this time only have a few heavy guns, but comparatively large secondary and tertiary batteries.
French and Italian Ironclads in combat
Poor accuracy and low armor penetration tend to make battles of this era somewat indecisive. There can be a lot of firing , but not very much serious damage. Torpedoes are in their infancy, and have short range and slow speed. It is hard to hit anything with them, but when they do hit, they can cause crippling damage. Damage control is primitive and torpedo defence systems are not developed, which means that a single torpedo hit can be fatal to an ironclad battleship.
An after battle look at the French Battleship Carnot. One torpedo is bad news for a predreadnought battleship, and two means a guranteed rapid sinking. As you can see from the ranges in the log, combat in this era tends to be at short ranges.
Poor damage control coupled with a weakness to fire of ships of this time means that fires often spread and get out of control. It can be a viable tactic to try to cause fires on enemy ships instead of penetrating their armour. Hits by high explosive shells (HE) are more likely to cause fires to break out than hits from armour piercing rounds (AP). In the doctrine screen, you can set the ammunition used by your ships against variuos targets. Try experimenting with using more HE, especially for medium guns and at longer ranges where AP shells will likely not penetrate anyway. If you do try that, remeber to adjust the ammunition loadout of your ships to carry a larger proportion of HE.
The doctrine screen with options for ammunition type used against different targets depending on range
The steam engines of the era are reciprocating engines that can only keep up high speed for limited time. This means that full speed is something to be saved for when it is really needed. If you zip around at full speed before closing with the enemy, you may find that your ships cannot reach their full speed when you need it most.
However, tecnical development is fast, and already in the first years of the 20th century, gun design, fire control and loading mechanization have progressed to the point where long range fire by heavy guns becomes more practical. Also, with better guns and evolutions in armor piercing shells, armour penetration will start to catch up with armour quality, and big guns can score penetrating hits at longer ranges. Explosives have advanced too, and shell hits will cause more damage. It is not a coincidence that the dreadnought battleship is developed around 1905, as technological developments have by that time made the all big gun battleship a logical next step. This leads us to the dreadnought era, which will be covered in the next Dev Diary.