The Collins Class Submarine Story

by Peter Yule

  tated during snorting and when sailing on the surface, mixing the

  oil with salt water, and it was almost impossible to avoid drawing

  salt water into the engines.5

  While the submarines’ designers concede that the fuel system

  was complicated, they believe that the crews were poorly trained

  in its use (training being an ASC responsibility as prime contrac-

  tor). In their view the crews tried to operate the fuel system in

  the same way as they had on the Oberons, rather than following

  the procedures laid down for the new submarines. Olle Holmdahl

  saw the main problem as being the crews’ practice of taking fuel

  from any of the tanks rather than following the recommended

  sequence. They were meant to keep the valves shut unless there

  were exceptional circumstances, but Holmdahl believes they rou-

  tinely opened them.6

  Eoin Asker and others connected with the project office tend to

  take a neutral view, conceding that the system was unnecessarily

  complicated, but also seeing poor crew training as exacerbating

  the problems. The problem of salt water entering the engines grad-

  ually lessened as the crews became used to the fuel system, but it

  was not until the system was supplemented with a navy-supplied

  fuel coalescer in 1999 that the problem was overcome.

  Crew members bridle at the claim that they were responsible

  for the failures of the diesel engines. Peter Sinclair says that the

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  crews were trained to follow procedures to the letter and ‘on the

  odd occasion [they] made mistakes but the problems that continu-

  ally occurred were due to design or manufacturing faults and any

  engineer or manufacturer that blamed the crews invariably knew

  he had problems’.

  The problems with the fuel system were exacerbated in the mid-

  1990s by persistent contamination of the fuel supplied to ASC by

  the navy. Throughout 1995 and 1996 the project office regularly

  reported that Collins’ trials were delayed by bacterial contam-

  ination in the fuel. This caused many problems in the engines,

  the most serious being damage to the fuel pumps. Swedish diesel

  engine consultant Olle Person recalls that he was asked by Hans

  Ohff to investigate the problems with the fuel pumps. After dis-

  cussions with the sub-contractors he decided that it was not a

  manufacturing fault but caused by a bacillus living in the fuel.

  Some products of the bacilli were corrosive and this caused the

  fuel pumps to stick. They had never had bacteria in diesel fuel

  in Sweden so this problem was new to them. The problem was

  eventually controlled by the addition of a biocide to the fuel.

  Salt water and fuel contamination were the most serious prob-

  lems with the diesel engines and lay behind many of the other

  difficulties, which included cracked or broken parts and exces-

  sive fuel consumption. However, there were other factors which

  are widely regarded as contributing to the failures of the engines.

  Quite early in the design phase, the decision was made to take the

  500-kilogram flywheel off the engines to save weight. Experts are

  divided over the effect this had, but many think that this made

  the engines less reliable and, by changing the natural frequency of

  the engine causing it to vibrate at its specified nominal operating

  revolutions, led to problems of cracking and breakages.7

  Greg Stuart, however, traces the excessive vibration to the fuel

  problems. He notes that:

  A number of studies were undertaken that showed the

  removal of the flywheel had no real impact on vibration. The

  proof of the problem was in fuel pump usage. The fuel

  pumps and injectors were a standard Bosch design. The usage

  and repair rate exhausted stocks of replacement pumps. The

  reason for replacement was corrosion. The corrosion had two

  sources; salt water and acid from bacteria. When fuel pumps

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  and injectors corrode they can do two things, the amount of

  fuel injected into the cylinder can vary and the point of

  injection can vary. Both of these effects cause irregular firing

  pressures which in turn causes destructive vibration. [This

  was] destructive to the diesel and all engine driven

  components including generator couplings and gear trains.8

  Excessive fuel consumption first showed up when Collins had its

  first full-power snort trial in May 1996, and meant that the sub-

  marine could not carry enough fuel to meet its endurance specifi-

  cation. Olle Person investigated this problem for Hedemora and

  concluded that the main cause was a manufacturing problem with

  the turbines leading to inefficiency in the operation of the turbo-

  chargers.

  The problems with the diesels led many to question the choice

  of Hedemora engines. Hans Ohff thinks that the Hedemora sub-

  marine engine was badly designed and suffered from numerous

  manufacturing defects. He believes Hedemora should never have

  been involved in the project because it was a small and declin-

  ing company that lacked the resources to develop and support

  submarine engines of the size required for Collins, or to remedy

  any defects. Ohff believes that most of the problems with the sub-

  marines were greatly exaggerated, but the diesels were – and still

  are – a genuine weakness, and he was angry that ‘the navy and

  DAO didn’t put their feet down and say “this is not the engine we

  want”’.

  On the other hand, Greg Stuart and others think that the

  Hedemora engines got a bad name because ‘we were trying to

  run them on salt water rather than diesel fuel’ and once the water

  separation was modified they improved greatly. Stuart concedes

  that the Hedemora ‘is a draught horse not a thoroughbred’, but

  he and other defenders of the selection of Hedemora point to the

  design advantage of being able to fit three abreast, the modular

  construction, which allows for easier servicing, and the fact that

  the engines ran with turbo-charged compressors driven directly

  by the exhaust gases.

  The diesel engines were a problem from the time Collins set off

  down the Port River for the first time, but noise only became an

  issue from the middle of 1996. Of all the problems the submarines

  encountered, this was probably the most unexpected. Swedish

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  submarines were extremely quiet and there was always the expec-

  tation that the Australian submarines would have the same char-

  acteristics. Further, the Swedish design had been assessed in 1987

  by the Australian evaluation teams as meeting the noise require-

  ments. In the Oberons the main noise concerns came from internal

  machinery, and consequently the Swedish technique of isolating

  all machinery from the pressure hull by mounting it on platforms

  was attractive for its potential to reduce machinery noise
to an

  absolute minimum.

  During the Cold War the Swedish submarine force was

  designed primarily to sit off the coast to attack a Soviet inva-

  sion fleet. The submarines did not have to cover great distances

  or run at high speed, so they were designed to be virtually silent

  at low speeds, in the ‘quiet patrol state’. In contrast, Australian

  submarines have long distances to travel to their operating areas

  and they want to do that as quickly as is possible while remaining

  undetected.

  While the requirements for range and endurance were clearly

  set out in the contract, the requirements for noise were less clear.

  This is indicated by the fact that there were bitter arguments at

  the time over what was actually required, and even today there is

  nothing approaching agreement on what the noise requirements

  really were.

  There is, however, general agreement that the original noise

  requirements and the way the requirements were expressed in the

  contract lay at the heart of the disputes over noise. Andy Millar

  suggests that the original specifications were vague because of a

  lack of technical understanding of noise issues in the Australian

  navy in the early 1980s. The Oberons were quiet, and when the

  specifications for the new submarines were being prepared it was

  decided to ask for them to be ‘twice as quiet’, even though it

  was not known whether this was achievable. Millar suspects that

  Kockums was uncertain whether the requirement was achievable

  but assumed it would get close.9

  However, even if the submarines had completely met the noise

  specifications set down in the 1987 contract, this would no longer

  satisfy the navy because expectations had grown. The contractual

  noise requirements concentrated on noise levels at quiet patrol

  state and when snorting, but were vague on noise levels at high

  speed, yet by the mid-1990s the navy saw an increasing role for the

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  submarines in directly supporting surface operations and wanted

  them to be quieter when travelling fast.10 Eoin Asker, an expe-

  rienced submariner who was involved with the project for many

  years, says that:

  The operators wanted to go faster and with less noise than

  the contract specified. They wanted to go at eight knots with

  a noise signature that was contracted for four knots but at

  this speed they made more noise and it was this that gave the

  perception that the submarines were noisy. The submarines

  got very close to meeting the contract – what changed was

  the operational requirement.

  Greg Stuart emphasises that the noise requirements specified in

  the contract were not changed, nor was the contractor asked

  to provide more performance than specified – ‘the operators

  may have wanted more but that did not flow to the contracted

  requirement’.

  The confusion about the contract requirements and the navy’s

  expectations was exacerbated by the difficulties of actually mea-

  suring the submarines’ noise. Ideally submarine noise is measured

  by a noise range in a deep fjord where the background noise of

  the sea is low, but Australia has few, if any, suitable sites, and

  none near the trials area off Port Lincoln. However, under the

  contract the navy was to provide a noise range and in late 1993

  the DSTO began surveying Spencer Gulf to find a site for a ‘shal-

  low underway radiated noise range’, eventually selecting an area

  near Thistle Island.

  The contractor for the noise range was a small Perth com-

  pany called Nautronix, which had been founded in the early

  1980s to develop marine signalling techniques based on research

  into the acoustic signalling of dolphins and whales. The tradi-

  tional noise range suppliers had no technology to measure sub-

  marine noise accurately in shallow water with a high level of

  background noise, but Nautronix worked out a way to adapt its

  technology to do this – although it was found that it was impos-

  sible to completely overcome the difficulties imposed by an inher-

  ently unsuitable site.11

  The first inkling that the new submarines might have noise

  problems did not emerge until June 1996, when the project office

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  expressed concerns with Collins’ noise levels. Six months later it

  reported:

  Investigation of problems relating to radiated noise are

  continuing . . . The opportunity was taken to put Farncomb

  over the [noise] range during December. Although defects

  at the range prevented an accurate set of results, the data

  collected suggested that Farncomb has a similar noise signature

  to Collins, suggesting that noise problems are class related.

  As this report indicates, the results of the noise range tests showed

  that the submarines were noisier than expected but there were

  arguments over whether the tests were accurate enough to estab-

  lish whether the submarines reached the contractual requirements.

  Hans Ohff agrees that ‘the submarines never met the hugely ambi-

  tious specifications for noise’, but argues that ‘it was hard to prove

  this because the background noise in the sea is greater than the

  noise level specified for the submarines’.

  While there is nothing approaching consensus on the noise

  levels of the first two submarines during their trials in 1996 and

  1997, the ‘median’ view is probably that of Peter Clarke, who

  judged that:

  The boats did not meet the noise specifications though they

  were not as far away as the navy tried to make out. At slow

  speed the boats exceeded the contract specifications for noise,

  but above seven knots it was iffy and at high speeds it was . . .

  over the contract.

  Whatever the exact noise levels, there is no doubt that the sub-

  marines were not as quiet as had been hoped and expected. What

  were the sources of the unexpected noise?

  Early in Collins’ trials there were some minor problems with

  mechanical noise, notably from the weight compensation pump,

  but these were quickly resolved. The main concerns were with

  hydrodynamic noise made by the flow of water over the hull, and

  noise and cavitation from the propeller. Critics like Mick Dunne

  and Bill Owen argue that the design of the submarine is inherently

  and irreparably noisy. While this view has been taken up by the

  general public, it is not shared by either the submarines’ builders or

  their operators. Peter Sinclair, as the first skipper of Collins, bore the brunt of the ‘first of class’ faults, but he is adamant that ‘she

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  is super quiet, really, really super quiet at slow speed, quieter than

  anything else in the world’. However, most agree with Sinclair’s

  observations that the submarines’ flow noise increased greatly as

  their speed increased
and share his view that the shape of the

  casing was the main cause.

  When the Type 471 was first designed the casing was smooth

  and even, being virtually indistinguishable from the Swedish

  V ästerg ötland class.12 A one-sixteenth scale model of this design

  was extensively tank tested in 1986 during the project definition

  study, showing hydrodynamic flows and noise levels nearly iden-

  tical to those of the V ästerg ötland.13 However, after 1987 the

  designers at Kockums were forced to make changes to this tested

  design. The most important of these was the sonar dome in the

  bow, which Kockums wanted to place low down, but the project

  office insisted that it be high to minimise the ‘blind’ area behind

  the submarine. The initial plans had a low bow but the changes

  resulted in a large and bulbous bow that is generally believed to

  be the major cause of turbulence and noise.14

  The changes to the bow were made with what appears to have

  been remarkably little consideration of the consequences for water

  flow. Although the issue was raised by members of the navy team

  in Sweden, they were told money was not available for a new

  model or test program.15 Consequently, the revised design with

  the larger bow was not tank tested. This reflects an early failure

  of communication between Kockums, the project office and the

  Australian navy. It was not until after tank testing and air flow

  analysis was carried out in the late 1990s that some relatively

  simple modifications were made to the casing that appear to have

  reduced the flow noise.

  The other noise-related concern was the cavitation from the

  propeller. Peter Sinclair recalls that during Collins’ trials they gradually became aware that at some speeds there was no cavitation,

  but at other speeds the water flow over the control surfaces onto

  the propeller did cause cavitation. Although the propellers and

  cavitation were hardly mentioned in the project office’s reports

  of the early trials, by 1997 they were among the major concerns.

  The chief of the navy, Don Chalmers, and American submarine

  expert, Admiral Phil Davis, both saw excessive cavitation as mak-

  ing the submarines unfit for combat. Don Chalmers recalls that

  the contract did not specify cavitation levels but:

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  What it said about cavitation was along the lines of ‘the boat