Why are RN Capital ships Complements

[bill24chev]

I have noticed that the complements of RN Battleships and Battle Cruisers are about 250 men less than German and USN ships of similer size and date of completion.

RN BB's around 750 to 800 German and USN BB's over 1100

Also the latest WW1 RN battleships The "Queen Elizaberths" and "R" classes (anout1000) have more than the earlier BB 's except for the "Iron Dukes" who have about 50 more men. I appreciate that the Queens E's and R's were bigger than the earlier ships but they were oil fired which should need fewer Stokers and had only four Gun turrets which would save the man power of one turret compared to early ships which had at least five twin turrets.

Can any one explain why theses differences?