Liberty's Provenance by John Henshaw

Author:John Henshaw
Language: eng
Format: epub
Tags: HISTORY/Military/World War I
ISBN: 9781526750648
Publisher: Pen and Sword

The agreed fee had been $750,000 for the first 200 – $3,750 per ship. The USMC increased the first order to 312 ships and expected the fee to remain frozen – reducing the fee-per-ship to $2,404. Gibbs held out for $3,077 per ship – $960,000 but settled on 24 June on the USMC’s terms.11 It was a swings-and-roundabouts equation. Whatever he figured they lost on that contract, they more than made up on the many other USN contracts.

CHAPTER 14: THE ESSENCE OF THE LIBERTY SHIP

So, what were the significant changes?

•Oil firing in place of coal. This meant deleting the bulkhead at Frame 81 that created the coal bunker and the size of Hold No 3 increased accordingly. Fixed ballast in the double bottom was removed and used for oil bunkers. This required oil filling facilities, extinguishing apparatus and various distribution piping, valves etc – quite a lot of complex plumbing but not, as they now say, rocket science.

•Water-tube boilers in place of Scotch boilers. The boilers were to be of the cross drum, straight tube type fitted with overdeck superheaters based on a Babcock & Wilcox design. These operated at 220 psi and 450°F (232°C) consuming about 30 tons of bunker oil per day at the hull’s economic speed of 11 knots. The boilers were, in effect, off-the shelf items but their installation and connections had to be worked out and documented. Again, not rocket science.

•Combining the previously divided accommodation into one centralised, midships bridge structure of three levels plus flying bridge. This was not a new or revolutionary idea. Refer, for example, to the British emergency war-built ships of the Type PF [B] and PF [C] which were of similar dimensions to the Liberty ship (448ft 0in LOA, 56ft 0in beam and 7,000–7,300 GRT) and which used the same basic hull and machinery but which had different superstructures, hold and cargo-handling arrangements to suit specific load requirements (see Chapter 6). Note how similar the two drawings are to the ‘Ocean’ class and the Liberty ship EC2-S-C1, respectively. One consequence of midships superstructure was that engineering and deck staff who had previously been well separated were still deliberately separated within the new bridge structure to suit British sensitivities. Lane says that the midships accommodation was more practical for North Atlantic crossings than the split accommodation and in addition to the safety offered was more economical with regard to piping and heating.

•Replacement of permanent and removable chain railing to the weather deck by steel bulwarks. This was a simple matter of continuing the frames up to bulwark height, extending the plating and installing scuppers as required.

•All-steel bulwarks to the bridge in place of canvas dodgers. The structure was already there, it was just a matter of infilling it with sheet steel.

•Replacement of round bar/radial davits with Welin-type davits. (Curiously, the ‘Ocean’ class were fitted with quadrantal davits but Liberty ships retained the simpler Welin type.)

•Reduction from seventy-five different thickness of plating to only twenty-seven. I have no details as to the effect on displacement.

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