Last week I introduced the game Naval Estimates and the competition I was running within it. The contest was entitled A better Invincible? and challenged the players to build just that. I gave them the original historical five line requirement for a big gun armoured cruiser provided by the Admiralty Board. There were 14 entries, all of them entirely feasible, even those few that would have looked somewhat bizarre to the Edwardian naval officer. I assessed each one according to a set of criteria, weighted with 600 points from quantitive performance data and 50 points from my judgement as a proxy Admiralty Board.
Clearly, the historical fidelity of this process depended heavily on how I weighted the performance data and set up the requirement for the competitors. Fortunately, the Committee on Designs is very well documented and there has been extensive secondary source commentary over the years - this gave me a good deal of confidence that I understood the real world design drivers1. The two aspects I rated most heavily were weight of all round fire power and speed2. The number of guns bearing, their rate of fire, accuracy and shell weight were all factored in, as well as raw speed and handiness. Protection, procurement cost, endurance, secondary anti-torpedo boat battery, upkeep costs and boat stowage were all assigned somewhat lesser weight. For all the factors, I normalised the data against the historical Invincible, which would have scored 600 points. I briefed the competitors that Admiral Fisher was very keen on maximum axial fire; that the Committee were very concerned about blast from the big guns disturbing the gun layers in adjacent turrets; and that steam turbines were preferred. I provided the blast templates used by the Committee to aid in their designs. Then I let them go away and do the work of the Committee. My only cheat was that I inflated the true cost of the real Invincible by 2% to give them more headroom for innovative design.
All the entries realised that, given the blast limitations, super firing turrets would greatly restrict axial fire opportunities. Broadly, the entries split into three groups. Firstly, there was those who eschewed offset turrets and decided to brave Jackie Fisher's wrath. The top two entries took this approach. Secondly, there were those who used variants of the historical en-echelon - both the third and fourth placed entries used this layout. And finally, there were those that just had a bit of fun - much to my surprise the most outre of these came fifth in the rankings.
The winner - HMS Incorrigible
This design was all centreline turrets, with better protection, superior anti-torpedo boat battery in casemates and slightly cheaper.
The leading wing turret design - HMS Inconceivable
Used an aft abreast wing turret arrangement rather than en echelon to get better arcs than the historical Invincible. Came third in the rankings.
The classic en echelon but better - HMS Irascible
This was the contest's real life Indefatigable clone, which it does very well and with more speed (25 knots full load)
A rather different solution - HMS Venerable
This was an attempt to imagine Invincible as a steam punk Victorian ironclad, a tongue in cheek 'meme' ship. To everybody's surprise it came fifth. Indeed, with only a single amidships mast and a bit more superstructure it would have done even better. Granted, the Admiralty Board would never have approved it, but it was an excellent bit of fun.
Finally, the staff answer
This was my staff answer, built with full knowledge of the algorithm and thus a cheat (like all staff answers). It is a 26 knot (full load) Indefatigable inspired en echelon.
So, what do we learn from this?
Firstly, Naval Estimates is already a pretty good construction simulator with a very respectable degree of fidelity - and it is going to get better. I gave the designers an in game brief and minimal contextual information. But with no particular knowledge of Edwardian warship design, all 14 designers produced effective alternative solutions to the Invincible design brief, all be it with varying degrees of plausibility.
Secondly, the fact that the winners eschewed the historical en echelon arrangement is interesting - essentially they went straight to variations of the centreline arrangement used from Lion onwards and produced better ships3. This illustrates the profound effect the Committee's focus on axial fire and blast had on all the first six battlecruisers, and indeed the first ten dreadnoughts.
Thirdly, the battlecruisers would have been entirely feasible with reciprocating steam engines. Both the leading designs used Vertical Quadruple Expansion engines. Parson's advocacy definitely swayed the Committee in favour of turbines, which were not strictly necessary to meet the requirement.
Finally, the cockles of my historian heart have been warmed by using a good game to spread good history to a wider audience.