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MULBERRY HARBOUR

Please note that this is an ongoing project and will be added to over what  could be quite a long period. The lists of tugs taking part may or may not be complete, but if you have any input then please contact me via the link on the home page. - Tug.
 
 
Photo RGR Colln
 
It became apparent in 1943 that in order to supply an invasion of the continent an artificial harbour would have to be constructed. There are many existing websites which can be viewed giving details of the planning of this operation, and construction of the  harbour, therefore I will concentrate only on the delivery of this harbour to the enemy coast by tugs. It may however help to understand the logistics of the operation  by briefly summarizing the various components involved in the Mulberry Harbour.

MULBERRY
This was the official name for the complete harbour installation. There were to be two complete harbours, Mulberry A for US forces and Mulberry B for British use.

PHOENIX
These were concrete caissons of five different sizes, the largest of which were 200’x60’x60’ and each unit weighed between 6044 tons and 1672 tons They were airtight floating cases open at the bottom with air-cocks to lower them to the sea-bed in a controlled fashion. Around 2 million tons of steel and concrete were used in their construction. They would form a breakwater to protect the harbour.  146  were constructed  by well known civil engineering contractors in 28 different locations  mostly in the south of England, including East India Dock [which had been drained for the purpose], South Dock, Millwall, Red Lion Wharf, Northfleet, Southampton Docks, Portsmouth Dockyard and Beaulieu River. When completed they were towed to locations off Selsey Bill and Dungeness and partially sunk on the sea bed to help avoid detection. An early trial  showed that a 750ihp tug could tow the largest units at 3 knots in ideal conditions.

GOOSEBERRY
A harbour of refuge for small craft  formed by sinking obsolete merchant and naval vessels on the 2 fathom contour.  70 obsolete merchant vessels and naval vessels  were amassed at Oban on the west coast of Scotland, stripped down, ballasted and primed with explosive scuttling charges. Some proceeded to the Channel under their own power, others were towed. They were concentrated at Poole Bay until required. This was known as Operation Corncob. 

BOMBARDONS
A floating breakwater comprising a steel cruciform structure which was used where the water was too deep to use either Gooseberry or Phoenix breakwaters. Each unit was 200’ in length. They  were the outermost barrier and therefore the first line of defence against rough seas.

LOBNITZ PIERHEADS
Constructed by the well known Clyde based shipbuilders and engineers in a special facility at Leith. These were complete pier head units, secured to the seabed by a ‘spud’ at each corner which could be mechanically adjusted to compensate for the rise and fall of the tide.

WHALE
The floating roadway which connected the line of Lobnitz units to the beach and were supported by floating pontoons called beetles.

It will be appreciated that with the exception of some of the Gooseberry vessels every component of the harbour would have to be towed from the manufacturing site to the operational area, either free floating or on barges or pontoons. Therefore a Towage Committee was instituted by the British Admiralty to procure and operate tugs for the project. A pool of 158 tugs was estimated to be sufficient. Agonising decisions had to be taken in regard to this procuring process, not least of which was whether to re-deploy rescue tugs then currently engaged in convoy rescue duties. The following pages  list  British, Dutch, French and US tugs known to have been involved in the operation.