Diana-- You are unwittingly mixed up. However, you are in good company. Even the crew mixed things up a bit when it came to the correct designations of boiler rooms, stokeholds, and bunkers.
Each boiler room had two stokeholds, except boiler room #1 which had only one. They were numbered moving forward. The lower number stokehold was at the after end and the higher number at the forward end of each boiler room.
BR #1 -- Stokehold #1
BR #2 -- Stokeholds #2 & #3
BR #3 -- Stokeholds #4 & #5
BR #4 -- Stokeholds #6 & #7
BR #5 -- Stokeholds #8 & #9
BR #6 -- Stokeholds #10 & #11
The bunkers were different. They were lettered, starting with "A" in boiler room #1 and moving forward to "b" in boiler room #6. In addition, there were two auxiliary bunkers on either side of the firemen's passage beneath hold #3, which were known as the #3 bunker.
Boiler room #1 -- bunkers A, B, and C
Boiler room #2 -- bunkers D, E, F, G, and H
Boiler room #3 -- bunkers I, J, K, L, and M
Boiler room #4 -- bunkers N, O, P, Q, and R
Boiler room #5 -- bunkers S, T, U, V, and W
Boiler room #6 -- bunkers X, Y, Z, a, and b
Most of the lettered bunkers were on a mezzanine level approximating the orlop deck. These were the bunkers where the trimmers broke large lumps into furnace-size coal and "trimmed" the bunkers servicing the boilers on the stoker level below.
Orlop Level -- bunkers A, B, D, F, G, I, K, L, N, P, Q, S, U, V, X, Z, and a.
The rest of the bunkers were vertical storage compartments that lined the watertight bulkheads. It was from these that the firemen drew fuel to feed the furnaces. Again, moving from boiler room #1 forward, they worked out this way:
BOILER ROOM #1
Bunker C
----Bulkhead J----------------------
Bunker E
BOILER ROOM #2
Bunker H
----Bulkhead H----------------------
Bunker J
BOILER ROOM #3
Bunker M
----Bulkhead G----------------------
Bunker O
BOILER ROOM #4
Bunker R
----Bulkhead F---------------------
Bunker T
BOILER ROOM #5
Bunker W
----Bulkhead E---------------------
Bunker Y
BOILER ROOM #6
Bunker b
----Bulkhead D----------------------
Bunkers #3 port & stbd
HOLD #3
So, there was no "bunker #10" in boiler room #6. There was, however, a stokehold #10 located at the after end of boiler room #6. Bunker Y served stokehold #10, while bunker b served stokehold #11.
After reading through the testimonies, I've come to the conclusion that the crew did not stick to these official designations with any precision. The boiler room numbers were used properly, but often as not the stokeholds (or "stokeholes") were often assigned the boiler room number, if identified at all.
The bunker letter designations do not seem to have been used by the crew. These seem to have been a convention of Harland & Wolff's drawing office. The letter designations were probably used by the engineers in calculating coal loading and burn rates. But, the "black gang" seems not to have been bothered by the letter designations.
-- David G. Brown