Bathurst Class Minesweepers (Corvettes)
- Payne, Alan
- Ship design and development
- None noted.
- HMAS Bathurst I, HMAS Deloraine, HMAS Katoomba, HMAS Koala, HMAS Kookaburra, HMAS Lithgow, HMAS Swan II, HMAS Sydney II
- Originally published in the Naval Historical Review (all rights reserved) of June 1980
HERMAN GILL IN HIS HISTORY of the Royal Australian Navy 1939-1942 stated that the Bathurst class minesweepers or corvettes were ‘an Australian modification of an Admiralty design’ and this view has generally been accepted as accurate. The design referred to was the Bangor class minesweepers, which were actually three separate designs with three different types of machinery.
As far as it is known only one Australian authority, Vice-Admiral Sir John Collins, has stated that the corvettes were in fact a purely Australian design. As it is extremely likely that Sir John is the only living authority on the genesis of the Australian corvettes it is most fortunate that his detailed account is available and is also backed up by the designer of the British Bangor class minesweepers.
“I would accept that the Bathursts were designed in Australia“, wrote Sir Roland Baker. “I do not suppose that there is anybody who really knows . . . . So far as I know the Bangor design was not sent officially to Australia but Commander Allison might have. Certainly at some point the Bathurst sketch design was vetted by me“. A sketch design is an outline design which gives little detail, and it is particularly interesting to note that Sir Roland makes no mention of seeing the final building drawings.
The Admiralty were certainly aware of the Bathurst design. It has been said that the Admiralty did not approve of the design and considered it inferior. This idea is totally unacceptable, as on the 30th June 1940 only five of the class had been laid down out of a total of seventeen ordered, and thirteen of these were to Admiralty account. It would almost appear as though it was the Naval Board and not the Admiralty who were unimpressed with the design. The Australian corvettes as built had a somewhat greater displacement than designed, and were somewhat heavier than the Bangors and had less power. Their maximum speed was only 13 knots and not the 15 knots for which they were designed. The Bathursts were twin screw for manoeuverability and also to make the reciprocating engines as small as possible, so that the engines could be built by railway engine builders and others not used to this type of machinery.
In 1938 Captain Collins was appointed Assistant Chief of the Naval Staff at Navy Office, Melbourne. Having served in the Plans Division at the Admiralty in 1933-34, Captain Collins knew that the Admiralty had earmarked hundreds of trawlers for local anti-submarine and minesweeping duties in the event of war.
“In dealing with local defence of ports I was concerned that we had no suitable trawler type vessels to earmark for local defence of ports. In fact little or nothing available in an emergency“, wrote Sir John Collins. “We had arrangements for the examination service and sea front defences and were busy planning for the boom and net defences (Boom Defence Vessels Kookaburra and Koala were laid down in 1938 and 1939 respectively). But we had no suitable M/S and A/S vessels to earmark for the approaches to Australian ports and the focal areas off these ports.
“We had just completed HMAS Swan, the last of the ‘first pair’ of Grimsby class sloops, and were considering building more of this type. These ships were ocean going, expensive and required skilled shipbuilders. The number needed for local defence M/S and A/S was beyond our capacity.
“With this in mind I wrote a paper entitled ‘A plea for smaller sloops in greater numbers’. To the best of my recollection it was approved by Admiral Colvin in June 1938, as I have a note in my diary that on that date I was busy on local defence planning.
“The essence of the paper was that, having no trawlers to earmark for local defence, we should build for local defence purposes a simple type of ship, small, reciprocating engines, one gun, elementary control with M/S and A/S capability suitable for use in the approaches to ports.
“As the programme proposal progressed through the Divisions and Departments, everyone wanted more put into the little ‘local defence’ minesweepers (we agreed to call them AMSs as a cover for their A/S capacity). The Gunnery people wanted better control and more guns, the M/S wanted shallower draught, the A/S more speed and etc. I took the view that the vessels, like the Admiralty trawlers, must be small enough to be built in Australian small shipyards, the engines must be simple and within the capability of Railway Workshops etc. and so the AMSs were developed from June 1938.
“As it turned out they operated in the seven seas and did a good job. I do not know the date of the original ‘parent paper’ of the Bangor class, but it is possible, as so often happens, that the same idea came to the two authorities at the same time. (But the British had their trawlers).
“I can state that the AMSs were not a modification of the Bangor class. They were evolved to fill the gap in the local defences of the approaches to Australian ports as we had nothing available from our peacetime merchant service for this M/S and A/S duty. Fortunately they proved capable beyond our dreams and became in fact, corvettes.
“So far as I can recall the Naval Constructor responsible was Mr. Leask, who certainly played a big role in their design.
“To sum up, whatever the dates of the Bangor and Bathurst designs, the AMSs were originated in Australia. It was fortuitous that a similar design developed in the United Kingdom, and that the AMSs were capable of ocean cruising“.
As Sir John remarked in his letter, Sir Roland Baker could have had no idea of the special Australian requirements or the great limitations of the Australian shipbuilding capacity. Although there is no evidence one way or the other that the Bangor plans were ever sent to Australia, the evidence of the designer of the Bangors and the instigator of the Bathursts is impossible to refute. It is perhaps ironic that the Australian designed a corvette that looked very much like a British minesweeper.
Captain Collins as Assistant Chief of the Naval Staff was too busy preparing for World War II to be deeply involved in the details of the AMS design and in any case he was appointed to the command of the cruiser HMAS Sydney in November 1939. Collins had nothing to do with the AMSs until he was appointed ‘Commodore Commanding China Force’ in Java in January 1942, so Commodore Collins had a number of AMSs under his command. It was most appropriate that it was in one of these small ships, the Burnie, that he left Java after that island was evacuated of those free to leave.
Today neither the Royal Navy nor the Royal Australian Navy has any corvettes, but the Royal Navy does has a class of Offshore Patrol Vessels, slightly bigger than the old AMSs. There is a design for a Mark II OPV and this carries a helicopter.
A modification of this design could be suitable for Australian requirements and it has a very long range.
Particulars of the Bathursts are given below:
Length overall – 186 ft 0 in.
Beam – 31ft 0in.
Standard Displacement – Approx. 800 tons (designed 650 tons)
Deep Displacement – 1020/1040 tons
Machinery – Twin screw Triple Ex-pansion 1750/2000 IHP
Maximum speed – 13.0 knots (designed 15 knots) at load draught.
Armament – One 4 in gun, One 40 mm Bofors, Two 20 mm Oerlikons & 40-70 Depth charges
Complement – 62 (As designed, 70 provided for)
Endurance – 2,640 miles at 10 knots.
As Sir John Collins has stated, the decision to call the Bathursts by the name of AMS was as a cover for their A/S capability. But in 1938 the term ‘corvette’ did not exist for modern ships, otherwise he might have called his paper ‘A Plea for more Corvettes’.
A total of sixty corvettes were built in Australia, thirty six being completed for the RAN and twenty on account of the British Admiralty. All the latter were manned by the RAN and commissioned as HMA Ships. The four remaining ships were built for the Royal Indian Navy. Bathurst, name ship of the class, was the first to be launched in August 1940 and was to Admiralty account. She completed on the 5th December 1940. It was fitting that the first Japanese submarine to be sunk by the RAN was sunk by three Australian built corvettes – Deloraine, Katoomba and Lithgow in company with the US destroyer Edsall on the 20th January 1942, about sixty miles west of Darwin.
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