I am sorry for this rather short reply, as I am a bit busy this evening. I had not seen this earlier - I appreciate the votes of confidence, Sam and Tom.
Tom, it's good to see you posting here for the first time.
My question is how did the post-Titanic modifications to Olympic and Britannic add to their survivability beyond this? We know the first 6 compartments could be flooded and they would stay afloat. Does this mean they could survive with any 3 or 4 sections breached as well?
There are quite a number of possible scenarios, Brent.
If I remember correctly, Edward Wilding indicated that the new arrangement provided for any of the
original groups of six compartments to be flooded. (Recall that there was a new, additional watertight bulkhead installed dividing the original electric engine room compartment into two - hence the 'original' reference.) As an example, if the forepeak, forward holds, and boiler rooms 6 and 5 were flooded (the forward six watertight compartments), then Olympic/Britannic would continue to float. Similarly, if the six boiler rooms were flooded, then in theory the ship would survive, as the watertight bulkhead at the head of boiler room 6 now extended to B-deck, and the bulkhead at the rear of boiler room 1 extended to B-deck. Or, you could have the two engine rooms, followed by boiler rooms 1, 2, 3 and 4 flooded with the ship remaining afloat (and immobile, for obvious reasons!) The two engine rooms and compartments aft could be flooded... These were the theoretical calculations, of course, and let's assume no portholes were open! The watertight bulkheads that were extended to B-deck were also strengthened further, since they now had to deal with increased strains if that sort of flooding were to occur.
It can be argued that the standard of watertight subdivision was then quite exceptional - certainly future White Star liners did not match it. (One interesting point to note is that two of the original watertight bulkheads that extended to D-deck were actually
reduced in height, for they were only watertight to E-deck following the 1912-13 refit. This is
very rarely mentioned.)
Some comments from 1932-33, regarding the subdivision standard:
Her disc draught was 34ft 2 1/4in — such a very precise figure! — and it was ascertained that with the ship drawing this much water, ‘a three-compartment standard with margin is attained over approximately 34 per cent of the ship’s length amidships’, in the boiler and machinery spaces. The so-called ‘three compartment standard’ indicated that with three of her major watertight compartments flooded amidships, the ship would remain afloat, and with a margin at that. It was noted that ‘there is also an inner skin throughout the machinery space and eight of the [watertight] bulkheads extend watertight above the bulkhead deck’.
Best wishes,
Mark.
