What could one 10,000-ton ship carry?

After my recent posts describing the SC and HX eastbound convoy systems, I received an email that said, in effect, “What was the big deal about loosing one ship out a 50-ship convoy? With an average loss rate of between 0.6% (for HX convoys) and 2.1% (for SC convoys), surely the war effort wasn’t hampered significantly by such a seemingly insignificant number of sinkings?” The answer is to consider that the ship itself represented the output of a complex industrial system plus the cargo it carried was the product of a number of others.

The cargo of a 10,000-Dead Weight Ton (DWT) ship equated to the carrying capacity of 300 train cars. One voyage produced enough revenue to pay for the ship. A single ship’s cargo could contain:

  • food for 225,000 people in the U.K. for a week or;
  • military vehicles to equip one infantry battalion or;
  • bombs to load 950 medium or 225 heavy bombers or;
  • aluminium to built 740 fighters, plus, carried as deck cargo:
  • two twin-engine bomber aircraft; and
  • lumber to build 94 four-bedroom houses.

Ask any army officer if the loss of all the vehicles for a full battalion of infantry in a single engagement equates to a ‘good day’ or a ‘bad day’ on the battlefield and I am sure the answer will be categorically ‘a bad day’.

While the loss of even one ship was bad enough, here is what happened when it really went wrong. The Battle for Convoy SC-107 in Nov 42 is considered to be one of the greatest convoy actions of the war. This was a 42-ship New York-to-Liverpool convoy escorted by the Canadian Escort Group C-4, comprised of the destroyer Restigouche, LCdr. Desmond W. Peers, CO and Escort Group Commander (known at the time as SOE, or Senior Officer Escorts), plus the corvettes Amherst, Arvida, Celandine (RN), and Sherbrooke. The corvettes Algoma and Moose Jaw had also been attached for the passage to the U.K. and for subsequent employment on Operation TORCH. LCdr. Peers had been the commander of an escort group for seven previous convoys, and he had been on escort duty since September '39, so he was experienced at the essential elements of this business. In fact, he had not lost a single ship up until this time. Peer’s job was made considerably more difficult because of a number of problems: the group was missing a second destroyer (Ottawa) which was under repair after ramming a u-boat, only two ships had effective radar sets and one of these was not working, and two commanders of corvettes had been changed just before this voyage. Despite its long-standing, the C-4 group was not a cohesive formation.

German naval intelligence intercepted and deciphered routine HF radio signals from the convoy and vectored the 17 u-boats of Group ‘Veilchen’ (Violet) westward to intercept it. The Convoy Commodore made the German operational aim of concentration easier by remaining on a steady course, rather than using a long-leg zigzag plan to make the uboats’ interception problem more difficult, and by continuing to make routine long-range radio signals. Attacks began on the night of 01-02 Nov and continued until 05 Nov. Marc Milner, in his book North Atlantic Run, describes the defence of the convoy by Peers as “valiant,” but the truth is that it was an unmitigated disaster.

The convoy arrived in Liverpool on 10 Nov 42 after having lost 15 of its ships (35.7% loss rate) over three days (02-04 Nov) to U-84, U-89, U-132, U-402, U-438, U-521, and U-522. U-402, KptLt. Siegfried Freiherr von Forstner, Knight’s Cross, CO, and U-522, KptLt. Herbert Schneider, Knight’s Cross, CO, each sank three ships and assisted in the sinking of another ship. U-132, KptLt. Ernst Vogelsang, CO, was sunk when it torpedoed the ammunition ship Hatimura at very close range, which exploded. All of U-132’s crew of 47 men were lost in this incident. Escort Group C-4 did not sink or damage any u-boats.

The shipping lost during the Battle for Convoy SC-107 totalled 82,430 tons. The 96,800 tons of cargo lost included:

  • 32,400 tons of ‘general’ cargo,
  • 11,800 tons of steel,
  • 9,000 tons of fuel oil,
  • 8,500 tons of grain,
  • 8,000 tons of tanks,
  • 7,500 tons of military transport,
  • 7,400 tons of zinc concentrate,
  • 6,200 tons of explosives,
  • 6,000 tons of ammunition, plus
  • an undetermined amount of lumber carried as deck cargo.
  • One hundred and fifty merchant seamen lost their lives in this engagement.

As stated earlier, the Allies’ great fear was the increasing number of u-boats would make interception of every convoy a distinct possibility, which would spread these ‘spikes’ of losses across the entire system. With losses averaging between 0.6% and 2.1%, and with 3.0% losses considered unsustainable, there was not a lot of surplus capacity to absorb the losses of the ships plus their valuable cargoes and the merchant crews.

Canadian shipyards built 354 emergency cargo ships during the war in three variants, all of them displacing 10,000-DWTs, which was the weight of the cargo, passengers, crew, stores, fuel and water when loaded to the summer seawater ‘deep’ condition. They were divided into the North Sands, the Canadian and the Victory classes. The only difference between them was the type of fuel they burned: the North Sands-class used coal, the Canadian-class could burn either coal or fuel oil, and the Victory-class burned only oil. All of these ships were patterned on the Ocean-class 10,000-DWT cargo ships built in the United States for Britain under the Lend-Lease Agreement. In turn, the more numerous and famous American Liberty-class merchant ships were patterned after the Ocean-class cargo-freighter. The primary difference between Canadian- and American-built emergency cargo ships was that Canadian freighters were of all-riveted construction while the American ships were welded. Ships destined for service with the British Ministry of War Transport were given ‘Fort’ names while ships retained for Canadian service were given ‘Park’ names.

Canada built 90 North Sands-class freighters for American order under the Hyde Park Declaration and these ships were subsequently provided to Great Britain under the Lend-Lease Agreement. The Hain Steamship Co., Ltd., of London managed the ships for the British government. Twenty-four of these Canadian-built ships were sunk (26.6% loss rate) and another twelve were damaged (one ship was damaged a second time). Four of the ships damaged were beyond economical repair and were declared Constructive Total Losses, raising the loss rate to 31.1%. Two of the other ships damaged were subsequently lost, bringing the final total loss rate for the North Sands-class to 33.3%. Their history is was chilling premonition of what might have been had a few things played out differently.