Tanjung Priok Dock of 8,000 tons was a floating dry dock built for Droogdok-Maatschappij Tandjong Priok (dry dock company Tanjung Priok) in the 1920s.
Context
Tanjung Priok, the harbor of Batavia/Jakarta The Indonesian capital Jakarta is on the shore of the Java Sea. For most of its history the 'harbor of Jakarta' was a place at sea where ships anchored, so they could load and unload via smaller ships. This changed when the newly constructed Port of Tanjung Priok (Dutch: Tandjong Priok) was opened 1881–1883. At Tanjung Priok ships could attach to a quay. The idea was that when the expensive transloading was no longer needed, the competitive position of Batavia would be strengthened.
Droogdok Maatschappij Tandjong Priok Tanjung Priok at first lacked a good repair facility, especially a dry dock. The repair shipyard of the Nederlandsch Indische Droogdok Maatschappij (NIDM) at nearby Amsterdam Island had Volharding Dock, but this was too small for most modern ships. The combination of a small dock and little traffic made that NIDM went into liquidation in 1884. The Maatschappij tot Exploitatie van Droogdokken en Scheepstimmerwerven in Nederlands-Indië then continued the business at Amsterdam Island into 1891. Just like her predecessor it failed to get the concession for exploiting drydocks in Tanjung Priok, and left Amsterdam Island in 1893.
What the Dutch government wanted, was to have a modern dry dock at Tanjung Priok. This required new capital that the public would not invest in the existing companies. In June 1890 it then made a deal that led to the establishment of the Droogdok Maatschappij Tandjong Priok (Tanjung Priok dry dock company). Part of the deal was that this company would lease Onrust Dock of 3,000 tons. It would also lease the cylinder dock free of charge. A new dry dock of 4,000 tons, i.e. Tanjung Priok Dock of 4,000 tons would be built in the Netherlands, and then be leased by the company instead of the 3,000 tons dock.
The Tanjung Priok dry dock company was an almost immediate success. In the company's first few years Onrust Dock of 3,000 tons was rather busy. After it started to use Tanjung Priok Dock of 4,000 tons in 1896, there were many years that this dock had more than 365 docking days a year. In 1904 the company got a patent slip of 2,000 tons. When the agreements with the government had to be renegotiated in 1915, government support ended, and the 4,000 tons dock was bought by the company for 350,000 guilders.
Ordering and construction
Ordering World War I was a happy period for Tanjung Priok dry dock company. In 1914 profit was 124,622 guilders, in 1915: 384,950, in 1916 185,402, in 1917 487,500, and in 1918 an astonishing 867.370 guilders. This trend continued in 1919 with a profit of 902,687, and over 1920 716,536 guilders These profits resulted in very high dividends for the shareholders. Nevertheless, by 1921 the company had a huge amount of cash available to invest.
On 3 December 1921 the order for Tanjung Priok Dock of 8,000 tons was placed at Burgerhout shipyard in Rotterdam. In relation to this order Droogdok Maatschappij Tandjong Priok emitted a loan of 1,000,000 guilders in bonds at 7%. The new dry dock would be 156 m long and would be able to lift 8,000 ton. It was claimed that it could also lift big ships like the Coen and Patria. It was to be ready in March 1923. The price was about 2,500,000 guilders, because it was on the balance sheet of 1923 for 2,509,526 guilders.
Construction For construction of the drydock Burgerhout shipyard cooperated with Hamburger Dockbaubüro of Paul Matthiessen and Max Müller, who also designed the dock. On 17 October 1922 the first part of the drydock, consisting of four pontoons, was launched. On 10 February 1923 the second part of the dry dock was launched. The shipyard did not make the planned end date in March 1923, because the plans were later changed to include a power station.
Characteristics
Tanjung Priok Dock of 8,000 tons was 156.40 m long overall. The pontoon deck was 146.40 m long. The beam was 29 m and the internal width on the pontoon deck was 21.4 m. The pontoons had a hold of 3.2 m. The sides were 10 m high. The 8,000 tons regarded the displacement of the ships which the dock could lift. The weight of the dock itself would be 4,000 ton. The maximum displacement would be 12,500 ton with a freeboard on the pontoon deck of 30 cm, which is what will happen if one puts a ship of 8,000t displacement on top of one of 4,000t: the combination will displace 12,000t.
The dry dock was self-docking. Each of the seven pontoons could be disconnected and be replaced by the reserve pontoon. After turning the disconnected pontoon 90 degrees, it could then be lifted by the dock. Meanwhile, the sides of the dock would stay in place. Each pontoon was divided in three parts, with the center part acting as air chamber. The amount of water in the side chambers could be regulated to make an exact fit during replacement of pontoons. The replacement operation was expected to be finished in 12 hours. It was an arrangement suited to the tropical circumstances, which required each pontoon to be maintained once a year. The reserve pontoon made it possible to delay actual maintenance till it could be lifted together with a ship which did not require the whole length of the dock.
The main pipe which was used for emptying the pontoons was placed in one of the sides, so it always stayed intact. Four electricity driven pumps of 400 hp were placed in the same side. Each had a capacity to pump 40,000 liter of water a minute The power would be enough to raise a ship of 8,000 ton weight in two hours. It also had the power station, and air compressors to drive tools were also placed in this side. On top of the sides there were two cranes that could each lift 5 tons.
The power station was added to the plans during construction. This was not the most obvious way to supply power to the dry dock, because a power station on land could be used for multiple purposes, e.g. powering two drydocks. Anyway the power station consisted of three big Diesel generators supplied by Mirrlees, Bickerton & Day. Each had 250 hp and they drove three 250 kVA generators supplied by Electrotechnische Industrie v/h Willem Smit & Co. The rest of the electrical installations was supplied by Siemens-Schuckert drydock construction from Hamburg.
Service
Passing the Meuse bridges
On 17 June 1923 Tanjung Priok Dock of 8,000 tons was planned to pass the Meuse bridges in Rotterdam. It would then be pulled to Batavia. Authorities and engineers were aware that passing the bridges could be problematic. The dock had a basic height of 13.20 m, and on top of it there were some deckhouses that were another 4 m high. A model of the riverbed was made by Burgerhout, and a model of the dock was combined with it to make calculations.
Smit International was to get the job done with 8 tugboats. The idea was to arrive before the railway bridge Willemsspoorbrug at 11:30 AM. Once there the top of one of the deckhouses would be removed. The dock would then be lowered till a draught of 6–8 m in order to pass under the railway bridge. After that, it would be lowered till a draught of 11–12 m to pass the (old) Willemsbrug. After that, the reserve pontoon would be pushed into the dock, and it would be pumped back up to its normal height.
On Sunday 17 June thousands had gathered near the bridges to view the spectacle. Press and camera were present, and there was even an airplane to do some aerial photography. At noon the two tugboats in front of the dock pass under the railway bridge, and the dock dives under it. Suddenly the current then grabs the dry dock, and push it sideways. The front of the dock is then a bit under the railway bridge while the rear is almost against the north shore of the Meuse. All tugboats present were then immediately pressed to pull back the rear. It was to no avail; even while 13 tugboats pulled, the drydock stayed put. The floating shearlegs Albatros was then brought upstream to remove the wooden deckhouse. Near three o'clock the tugs lost control for a moment and had to start all over again in their attempt to straighten the dock. The incoming flood then helped, and at 3:40 PM, the dock started to move again. At 4:00 PM, the dock was below the railway bridge. The sea tug Achilles was then able to help, and at 4:15 PM, the front of the dock was below the Willemsbrug.
Next the dock was solidly stuck in the bed of the Meuse. The sea tug Argus, which could not pass the bridges, joined in as the 15th tugboat. By seven o'clock the dock had progressed some dozens of meters. At 8 PM the dock was below both bridges, the stern under the railway bridge, and the bow under the Willemsbrug. At 11 PM it was still in the same place. All night long the tugs then pulled and pushed. Obstacles on the southern side of the dock were hastily cut off at 4:00 AM, so the dock could be brought up a bit. Finally, somewhat past 8 o'clock in the morning of the 18th, the dry dock came free of the bridges. In the end, it had passed the bridges at precisely the planned place. At 10 o'clock Tanjung Priok Dock of 8,000 tons was in the Waalhaven, where the pontoon would be loaded, the final deckhouses be fit, and the dock made ready for sea. Later an unexpectedly strong current from the old harbor was blamed for the mishap before the railway bridge, which made the whole plan go awry. Later the total damage was estimated at 30,000 guilders.
Tugged from Rotterdam to Batavia Tanjung Priok Dock of 8,000 tons now had access to open sea, but still had to be brought to Batavia. After a thorough inspection, and after all preparations had finished, the dock left the Nieuwe Waterweg on 12 July. She was pulled by two ocean-going tugs. Humber (ex Atlas) of 520 ton and 1,500 hp had captain Willem Verschoor, overall commander of the expedition, and navigator T. Vet. Poolzee of 300 ton and 750 hp was captained by Van der Hoeven, who had his nephew Van der Hoeven as navigator. The dock itself was commanded by dockmaster Strijbos. On board Humber the radio telegraphist Mr. Spruit would send letters about the voyage. The journey was expected to take four months. On 13 July the ships were 10 miles west of Beachy Head. On 16 July they were 50 miles south west of Start Point, Devon. On 20 July they were at On 24 July they were 60 miles from Vigo. On the 27th they were at the altitude of Cabo da Roca. On 2 August the convoy was 60 miles east of Cabo de Gata On 4 August the ships were near Algiers. On 10 August they were near Cape Bon (Tunesia). On 13 August the convoy was 70 miles east of Malta. On 16 August they were at .
On 24 August Humber and Poolzee entered Port Said towing Tandjong Priok. On 28 August they continued their voyage. On 30 August they passed Suez. On 8 September the ships were at in the Red Sea. On 13 September they passed Perim in the strait of Mandeb, exiting the Red Sea. On 15 September the dock was near Aden, where the tugs bunkered in turn. On 17 September the convoy left Aden again. On 20 September they were 125 miles west of Cape Guardafui. On 26 September they were 77 miles east of Socotra. On 2 October the convoy was at On 8 October they were 130 miles west of Minicoy. Near Minicoy the convoy was overtaken by SS Rindjani. She had Mr. D. Croll CEO of the Droogdok Maatschappij on board, and Rindjani thus searched for and found the dry dock.