Kanguro was a Spanish Navy submarine rescue ship in commission from 1921 to 1939 and from 1940 to 1943. Although she never had an opportunity to recover a stricken submarine, she performed the roles of a submarine tender, a floating drydock, and a salvage ship during her time in commission. She served under the Kingdom of Spain until 1931, then under the Second Spanish Republic. Under repair when the Spanish Civil War broke out in 1936, she remained under the control of the Republican faction during the war, but did not operate during the conflict. After the Nationalist faction won the war in 1939, she was incorporated into the naval forces of Francoist Spain. She was scrapped in 1946.
Design
Kanguro was a large catamaran — the first catamaran to serve in the Spanish Navy — with twin hulls. Her builders designed Kanguro′s two hulls by splitting a standard hull form measuring in length and in beam and dividing it in half along its longitudinal centerline. A heavy structural framework joined the two halves, forming a forecastle at the bow and a quarterdeck at the stern and creating an central tunnel between the hulls. Despite her size and her unconventional design, she reportedly was very manageable, handled very well, and displayed good seaworthiness even in rough seas.
A central gantry crane spanned Kanguro′s tunnel. It had a system of four horizontal lifting mechanisms, each with a large block-and-tackle system with eight flexible 50 mm (2-inch) cables. Each lifting mechanism was powered by its own electric motor, and each could lift approximately 165 tons. This allowed Kanguro to lift submarines up to in length and displacing up to 650 tons from a depth of at least to a height of above sea level within the central tunnel. The lifting mechanism then could lower the submarine onto two keel blocks in the tunnel, creating in effect a floating drydock in which the submarine could receive supplies and undergo simple repairs. A submarine also could enter or exit the tunnel while partially submerged, if not while fully surfaced.
The structural framework joining the two hulls created a spacious platform which accommodated Kanguro′s bridge and a large central control room from which Kanguro′s crane operators could control the four crane motors remotely. The operators could operate each motor separately, allowing the operators to center the weight being raised and even tilt the submarine being lifted longitudinallyif that was necessary to rescue personnel from it. Two windows allowed the operators to view the cranes' cables while they were in operation. Each block-and-tackle system automatically compensated for differences in elongation between the cables so that the load would be distributed equally among them. Kanguro also had an underwater automatic hook-up system built into the bottom of the 7.5-ton lower pulley blocks designed to automatically latch onto a sunken submarine underwater without requiring divers to manually connect cables. This system did not prove to be useful, however, because it only worked if the submarine was constructed with bulky, heavy custom fitting points on her outer hull and if she was sitting upright on the seabed — a very unusual rescue scenario. Kanguro carried a geometric test block which could be filled with water until it weighed up to 700 tons; it allowed Kanguro′s crane operators to practice lifting operations without risking damage to an actual submarine.
To support a submarine once it had been lifted from the water, Kanguro had two 20-ton movable keel blocks. The ship's four steam winches could move the keel blocks using steel cables. To allow a submarine to enter or exit through the central tunnel's forward entrance, the bow keel block could be hoisted out of the way using a pair of davits. However, vertical clearance at the forward entrance was limited even after the block was lifted as high as possible, requiring even a small submarine with its periscopes lowered to enter and exit the tunnel's forward entrance while semi-submerged.
In addition to the main heavy-lift crane system, Kanguro′s central tunnel had a separate system of cargo-handling cranes. This consisted of four overhead cargo cranes — each powered by its own steam engine, each with a wheeled cargo trolley running along a beam, and each capable of lifting five tons — and a single electric overhead monorail crane which could move longitudinally along the length of a submarine in the tunnel and lift heavy components out of her. The electric monorail crane could transfer its load to any of the four horizontal cranes and vice versa.
Each of Kanguro′s two hulls was identical. The forward section of each hull had storerooms, crew accommodations, a chain locker, and water storage. Each hull had a winch at the forecastle level for the main rigging powered by a motor. Aft of the winch, each hull had a boiler room and coal bunker. Aft of that, each hull had, consecutively, a power plant, consisting of a 200-kilowatt, direct-current, 250-volt electric generator; a drum for the corresponding main rigging; and a triple-expansion steam engine that drove each hull's propeller. Further aft still were more crew accommodations, storerooms, water storage, and an aft chain locker. The only difference between the two hulls was that the starboard hull had a storage compartment for twelve torpedoes and a warhead magazine, while the corresponding space on the port side housed a workshop equipped with the tools for minor repairs and maintenance of submarines. In the structure joining the two hulls, a habitable space existed both in the quarterdeck section and beneath the forecastle. Kanguro also had accommodation space for submarine crews, compressors, a voltage booster for charging submarine batteries, tanks for naphtha, oil, lubricants, and distilled water for use in batteries, radiotelegraphic and submarine signaling equipment, and diving equipment,among other things, all features that allowed her to function in the role of a submarine tender.
Kanguro was long, with a beam of ; and a depth of hull of . Her draft with all cargo aboard was ; with a submarine aboard it was . Her two steam engines drove two propellers, giving her a maximum speed of without a submarine aboard and with one aboard. She displaced 2,480 tons. At full speed she had a range of , and at her economical cruising speed her range was . She had a crew of 97.
A significant drawback of Kanguro′s design was that her main and auxiliary services all depended on high-pressure, ordinary-type boilers for their operations rather than on main and auxiliary diesel engines. This meant that when shut down the ship required 10 to 12 hours to power up her systems, unacceptably delaying her response to a submarine accident. Thus, Kanguro′s crew had to keep one of her main boilers pressurized whenever Spanish Navy submarines were conducting training — four days a week from 09:00 to sunset — so that she could get underway quickly in the event of an emergency. This burned a great deal of fuel and led to excessive wear on her boilers and steam engines.
Kanguro'''s central tunnel was large enough to accommodate the Spanish Navy's first four operational submarines — and the submarines , , and — all of which were commissioned in 1917 and the last of which was retired in 1934. Her tunnel was too small to accommodate Spain's later submarines — those of the B class, which were commissioned between 1922 and 1926, and C class, which entered service between 1928 and 1930 — although she nonetheless served them as a submarine tender.
Construction and commissioning
On 17 February 1915, the Spanish Cortes Generales passed the Miranda Law, a naval construction program which called for a Spanish Navy force that included 28 submarines and provided for the acquisition of the Spanish Navy's first four operational submarines. The frequency of submarine accidents in the early 20th century and the resulting loss of life prompted the Spanish Navy to prioritize the acquisition of a submarine rescue ship capable of lifting stricken submarines from the seabed and bringing them to the surface in the event of an accident, and so the Miranda Law also provided for the acquisition of such a vessel.
Werf Conrad, a respected company in the Netherlands which specialized in the construction of dredges and special machinery, came forward on 1915 with an offer to build a double-hulled salvage ship with the capability to recover submarines of up to 650 tons displacement. The design was known commercially as a "Kanguroo" type, derived from the name of Kanguroo, a ship of similar design constructed in France for the Peruvian Navy. The Spanish Ministry of the Navy asked Werf Conrad for further details on the vessel it proposed, and at the same time invited the Sociedad Española de Construcción Naval (Spanish Naval Construction Society; SECN), an Anglo-Spanish conglomerate, to submit proposals for the construction of the ship. On 20 April 1915 SECN submitted two designs, one from Vickers called Design 653 and another from Armstrong Whitworth known as Design 741. Design 653 could lift a weight of only 450 tons, even though the Spanish requirement was a lifting capacity of 650 to 700 tons. Design 741 was a twin-hulled vessel of the "Kanguroo" type, but otherwise SECN provided little information about either design and no price information, SECN’s British partners preferring that the Spanish Ministry of the Navy first specify the type of salvage vessel it wanted so that SECN could tailor its design to those requirements.
Meanwhile, the Spanish Navy's technical departments reported favorably on Werf Conrad's proposal. In addition, the Spanish Navy found Werf Conrad's offer attractive partly because the Netherlands, like Spain, was neutral during World War I, which had been raging since the summer of 1914. This offered Spain the hope that Dutch neutrality would mean that construction of the ship in the Netherlands would not face the delays due to shortages of materials and competing priorities that it would if a belligerent country like the United Kingdom was involved in her construction. In June 1915 the Ministry of the Navy came to an agreement with Werf Conrad to build the ship at a cost of 79,000 pounds sterling, equivalent to 1,990,800 pesetas at the prevailing exchange rate. The Spanish Navy signed a contract with Werf Conrad on 1915 which called for the ship to undergo sea trials from a Dutch port within 12 months and then be delivered to the Spanish Navy at a Spanish port.
The ship received the shipyard project number 486, and her keel was laid in 1915 at Werf Conrad's shipyard in Haarlem as soon as the company could gather the necessary materials, a process delayed by wartime shortages despite Dutch neutrality. Construction fell behind schedule, and Werf Conrad did not launch the ship until 1916. Additional delays followed. When the ship was completed in July 1917, she was moored at Amsterdam, with plans calling for her sea trials to take place in the roadstead of the Nieuwediep, but the war situation on the Dutch coast made it difficult to obtain permission from Dutch authorities to conduct the trials. Permission to conduct them did not arrive until October 1917, after the Spanish Ministry of State interceded. Meanwhile, a severe coal shortage in the Netherlands had prompted the Dutch government in July 1917 — the same month as the ship's completion — to suspend the supply of coal to foreign ships in the Netherlands, so that when Dutch authorities finally granted permission for the acceptance trials it was difficult to procure coal with which to fuel the ship for her trials and eventual delivery voyage to Spain. Spain tried to work around the Dutch coal ban by positioning 600 tons of coal in the Netherlands in neutral ships, but this effort failed, and in the end it proved impossible to conduct the trials during the war, which did not end until November 1918.