Extrait de THE EMPIRE SHIPS de W.H. Mitchell and L.A. Sawyer
‘TID’ type tugs
When urgent demands were made for small tugs for harbour and dock work, the terse statement made to satisfy the needs was simple: it stated 'design, organise and start work immediately toward achieving; in the shortest possible time, the delivery of one tug per week, using in the process, little or no shipyard labour'.
A survey showed that constructional engineering yards were already hard-pressed by the industry and could not accept orders for tugs, generally launched from conventional slipways. However, there was more capacity in manufacturing establishments for welded work rather than riveted work. It was evident that the planning must allow for the work to be placed with a number of different firms, and the basic design for an all-welded tug emerged.
Pre-fabricated construction in shipbuilding had risen to huge proportions in the United States but there was little, if any, in Britain. Now, however, its possibilities were investigated, with a tank-tested model requiring only minor modifications before acceptance. The result was a complete departure from normal British shipbuilding practice, in shape, in design detail and in the construction of pre-fabricated parts for the assembly of a vessel. It was an advance in technical and industrial development.
So came the TID tug -the Admiralty abbreviation of Tug, Inshore and Dock. It was to be mass-produced and of straight-line form, all design lines of the same strake of plate being parallel, giving frames in straight lengths. There were to be no bent frames and curvature in the shell would apply in one direction only, i.e., with no twist in the plates.
Initially, contracts for parts were awarded to four contractors, but quickly increased to thirteen. The design was subdivided to eight units, cut right across the vessel, with alljoints of units arranged to come midway between two frames. There were independent drawings for each unit, with the unit sizes restricted to maximums of 10 ft length, 17 ft width, 13 ft depth and a weight of six tons for transport by road, sometimes up to distances of 200 miles.
Some contractors were able to produce more than one unit, and with each the longitudinal seams of plates were left unwelded for a length of ten inches at either side of a joint, in order that the plates might be 'sprung' together if any slight deviation from the correct dimension occurred. Each separate unit was completed with many of its fittings in position: a special feature of the after-most unit being that it was completed with the rudder, propeller and tailshaft in place. At fitting-out stage -after completion and launch of the hull -the engine bedplate chocks were machined to dimensions taken from the engine after it had been packed and wedged up in alignment with the tailshaft.
However, with some fittings -namely engine room valves, pipework and auxiliaries -it was deemed unwise to have these fitted to the units by the sub-contractors, due to possible movement by vibration during transit. Therefore, such items were fitted at the shipyard, prior to the transverse all-round welding which turned eight separate units into a complete tug.
Hull measurements of the tug were 65 ft length (bp), 74 ft (oa), 17 ft breadth and 8 ft depth, giving 54 gross tons. The draught was 7.3 ft with bunkers and water tank full. Full displacement was 124 tons, bollard pull two tons and full bunker capacity eight tons (coal) or nine tons (oil).
Assembly of the hull was done by Richard Dunston Ltd., at their Thorne and Hessle shipyards in Yorkshire and late in the programme, to keep up with demand, by William Pickers gill & Sons Ltd., at Southwick, Sunderland.
A hull was put together every five days -the record was four -and the vertical boiler, two-cylinder compound engine which developed 220 ihp, and superstructure were fitted after the launching. For this purpose, units Nos. 4, 5 and 6 had their upper casings merely, tack-welded into position by the contractors. These were removed by cutting the tacks and were e~sily replaced afterwards.
With Dunston's constructions the first TID was towed to Hessle from Thorne, had her engine and boiler fitted, ran trials back to Thorne and as she left for delivery towed the next completed hull downstream for its machinery installation. This went on week after week, each completed TID towing the next one.
During the four years of TID building, their appearance changed little, only minor changes to the deckhouse, boiler room and accommodation being made, most of these on the Sunderland-built craft.
The initial order from the Ministry of War Transport for twelve TID tugs quickly became twenty-five; then, as production began, was altered to fifty, and as work quickly progressed the figure was doubled to 100. All were ordered as coal burners, to give 7-8 knots and with the liberation of Europe in mind, the main intention was for their use incsmaller ports and anchorages.
Then came the likelihood of the use of TID tugs in the Mediterranean and the Far East and another fifty were ordered. But it was necessary to modify the design to make them burn oil, this due to the lack of coal -or its generally poor quality -at prospective bases and to give increased range to the vessels. Such conversion, including lowering funnels, required only slight structural modifications to two of each set of eight prefabricated units. At the same time it was decided to convert similarly the second batch of fifty tugs ordered, but with these already in production it was found possible to change only ten of them to oil.
Finally, a group of thirty-two oil-burners for tropical service was built, with generators to operate ventilator fans and fitted with electric light. The tugs were numbered 1 to 12 and 14 to 183. Many were allocated to naval work and a number of them were shipped to Eastern waters as deck cargo aboard heavy-lift vessels. Such voyages can be exemplified by the departure from Liverpool on 22 May 1945 of the Empire Byng, with TIDs Nos. 125, 126, 131, 132 and 133 as deck cargo. She arrived at Bombay on 19 June.
Similarly, TIDs Nos. 122, 123, 124, 129 and 130 were shipped to the Pacific and, in June 1945, joined the British Pacific Fleet at Manus, in the Admiralty Islands. The islands had been established as a forward base in the January, enabling the Royal Navy and its associated Fleet Train of supply vessels to operate successfully thousands of miles north of its main bases in. Australia. A total of more than 800 ships -naval and merchant -were assigned to these operations, but the sudden end to hostilities in August 1945 caused many of the vessels to be diverted or dispersed.
By October 1945 a number of the TIDs had reached Hong Kong aboard the Empire Charmian, whilst others (TIDs Nos. 127, 128, 144-149 and 151) were despatched there from the U.K., as under-deck cargo on the Empire Marshal, on her maiden voyage in November 1945.
Earlier, in the July, a further batch of TID tugs, still in the U.K., were to be refitted and tropicalised for Eastern service, although in the event these plans were not carried out.
When the war ended some of the TID tugs engaged on naval work were given a permanent transfer to the Admiralty, for continued service at navy bases throughout the world. Most of those which had served with the Army reverted to Ministry of Transport jurisdiction before post-war disposa~ with a number allocated to various dock and harbour authorities and others to towage and lighterage companies. In addition, a considerable number were sold to Continental buyers in France, Belgium, Holland, Finland, Norway and Sweden -and even one as far away as Uruguay. However, it has not proved possible to trace the entire subsequent history of a number of them.
The fourteen TID tugs sold to Finland made the passage to that country in three 'convoys', eight of them (see TID 1) sailing in October 1946, three (see TID 69) sailing from Great Yarmouth on 25 April 1947 and three (see TID 19) sailing from Dover two days later.
A batch of eleven went to the French Government in December 1945, then passed to the civilian administrators of various Channel ports. In 1948 one of them (TID 20), was shipped to French Indo-China and three years later five more followed, still retaining their Till pr~fix but renumbered TIDs I to V. And by 1947-1948 another ten or so had also passed into French ownership.
TID tug orders summarised:
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