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Australian Patrol Boats, now it the time to get it right


Australia, yes its a big place

Australia is a big place, in fact real, real big. If you were to measure every bay and headland and measure the length of coastline Australia has you would arrive at a figure of 35,877km or 22,290 miles. Australia has an area of 7,692,024 square km or 2,967,487 square miles. Australia is 4000km from East to West at its widest 3100km from the farthest point North to its lowest point South. Australia has a small population of about twenty two million people as of the year 2012

Many parts of Australia are uninhabited and much of its coastline is devoid of people. Of Australia's 22 million people, most live in the South East corner. In fact as of 2006 only 960,000 people live north of the Tropic of Capricorn in an area of 3 million square kilometres. It is true that Northern Australia is growing fast in terms of population and also massively in economic terms. Despite this growth it would be a most fair generalisation to say that northern Australia is very big and is very sparsely populated.



How does Australia protect its borders

The organistaion that is meant to protect our borders is border protection command From its website it is meant o to the following

Border Protection Command is responsible for coordinating and controlling operations to protect Australia's national interests against the following maritime security threats:

  • Illegal exploitation of natural resources
  • Illegal activity in protected areas
  • Unauthorised maritime arrivals
  • Prohibited imports/exports
  • Maritime Terrorism
  • Piracy
  • Compromise to Bio-security
  • Marine pollution.
Assets of Border Protection Command

BPC has assets of the Australian Customs service and the Australian Navy
  • These include 15 Royal Australian Navy (RAN) Armidale class patrol boats
  • 14 aircraft operated by Surveillance Australia, mostly Dash-8 aircraft and similar types
  • Eight 134t Australian Customs Bay class customs boats
Now the BPC could in theory call upon other Australian Navy ships if they happen to be in the area, additionally they can call upon 19 Royal Australian Air Force Lockheed Orion PC3-II anti submarine aircraft of which Australia, though these have other tasked such as looking for submarines, surveillance in Afghanistan, the Persian Gulf and also in training for their main role





Now with these 37 platforms Australia is meant to protect its borders. It is not quite as bad as it first sounds as the aircraft are quite good and can reconnoitre a huge area. Other Navy ships can be called into play on occasion but this is not their main job. The planes are best for seeing what is out there, but they can't stop a vessel or plane and see what is going on inside the way that a boat can. Furthermore boats from Indonesia have a way to go and are likely to be detected by aircraft (though certainly not always). The Customs bay class are small at 134t and it seems operate fairly close to home ports. Another little factor to consider is that of these 37 platforms several will be in maintenance at any one time. Last but not least Australia has the Jindalee over the horizon radar network (JORN), this is apparently quite good at detecting aircraft, but not quite as good as at detecting small slow moving wooden boats (assume this to be due to lack of Doppler effect and radar clutter)



What is a Patrol Boat and how is it different from a corvette or FAC?

A patrol boat is a simple low cost craft that performs a variety of patrol functions. Its primary purpose is not to fight the armed forces of other nation states in warfare. A corvette or even a Fast Attack Craft (FAC) is a different type of vessel. Its main aims are to attack enemy surface ships and also be able to protect itself from enemy planes whilst doing so. In short an FAC or Corvette is designed to fight a war against another nation state. Now in recent times FACs have fallen out of favour to a degree as they have limited survivability from air attack and provide poor weapons platforms for their SSMs, this being due to their lack of intrinsic SAMs and the position of their search radar for SSMs which is lower to the horizon, smaller and also more subject to ship movement, further degrading radar performance.

FACs are still used in some countries, often for nations without the money to afford 'proper' warships, and also for nations where the enemy might be close-bye high speed and ability to hide are important factors. Places that come to mind are the Baltic, the Agean, and SE Asia. A reasonable assumption to make is that FAC are not really suited to Australia, and hence we have concentrated on larger surface warships and submarines to fight nation states, and on relatively simple and cheap Patrol Boats for routine tasks where a highly sophisticated larger surface combatant would be wasted. I think it is fair to say that this has been a smart move.

To summarise, a patrol boat is relatively simple and costs a tiny fraction of a destroyer or frigate. FACs and corvettes are for fighting other warships (nation states) whereas patrol boats have much more mundane duties. These mundane duties include

  • Patrolling waters
  • Maintaining a presence in territorial waters
  • Stopping and interdicting suspicious vessels
  • Stopping drug traffickers
  • Stopping terrorists (Mumbai anyone?)
  • Multi Force Covert Operations

  • Preventing illegal fishing
  • Assisting with biosecurity (foot and mouth disease etc)
  • Assisting vessels in distress, sinking yachts etc
  • Interdicting and boarding suspected illegal entry vessels (asylum seekers / illegal immigrants)
  • Protecting offshore oil and gas instillations
  • Protecting merchant vessels against pirates
Now it is true that larger vessels can do these tasks but often at much higher cost something that is explored more fully below



Costs of larger ships vs smaller Boats

Ships and patrol boats all cost a lot of money. However this is all relative. The Australian Economy has an annual GDP of 1.57 trillion dollars (average GDP per head = $69,000). The defence budget as of 2012 is 24 billion dollars or a fairly low 1.57 percent of GDP. With the federal government set of achieveing a surplus this financial year money for defence is tight.

So we know that money is tight and additionally we know that the Australian economy is pretty large and doing fairly well (much better than Europe and USA). Thus we now come to ships and boats we can look at costs, both initial and ongoing.

Costs of naval vessels (unit cost), some examples

  • Armidale class patrol boat - Australian built 270t - 25 million dollars
  • Kilic FAC - Turkish built - 560t - 40 million dollars
  • Gumdoksuri - Korean built - 570t - 38 million dollars
  • Knud Rasmussen OPV - Danish built - 2050t - 50 million dollars
  • Anzac class frigate - Australian built - 3600t - approx 700 million dollars

Looking at the above list shows that size of vessel is not a good indication of cost. Proper warships designed to fight in a high threat environment tend to cost a huge amount, but this money is essential otherwise they would not survive in conflict. On the other hand, relatively simple vessels are much cheaper and also as the size increases the cost only increases slowly. Another way of thinking of this is that steel is fairly cheap and weapon systems and sensors are very expensive. Thus knowing that increasing the hull size increases costs only slightly, there seems no logic in making vessels small and cramped, better to make them a bit bigger to assist with sea-keeping, habitability, range, speed etc

Example of a large ship that is relatively affordable: Danish Knud Rasmussen class OPV
  • 2050t full load
  • less than 17 knots max speed
  • unit cost 50 million dollars (only twice that of a 270t boat)
  • Nice simple ships, low capital cost though speed is slow



History of Australian Patrol Boats

The history of Australian patrol boats can be summarised very simply as Attack class, then Fremantle class then Adelaide class

Attack Class

The Attack class were small boats of 146t fully loaded, and built from 1967 to 1969. They were relatively small steel hulled boats used mostly to patrol Australia's northern coastline. It should also be remembered that at the time these boats were built Papua New Guniea was still an Australian protectorate, and thus a presence was required in those waters. Apparently they were solid reliable boats, though quite small and cramped and did tend to roll a great deal in any weather. They were apparently well built with some still in service in Indonesia (they were given away) in 2012 which is 45 years after they entered service, though it seems that thesedays they are probably mostly used for short patrols not far from home port

Attack class patrol boats

  • size of class = 20
  • 100 tonnes unladen
  • 146 tonnes full load
  • all commissioned from 1967 to 1969
  • most paid off in mid 1980s
  • seven transferred to PNG and Indonesia in mid 1970s
  • Steel hulled, some still serving in Indonesia as of 2012


Fremantle Class

The next boats to enter service were the Fremantle Class. These were a class of 15 boats built from 1977 to 1984 and retired in the mid to late 2000s. These were 220t boats and much larger than the preceding Attack class. They were built of steel and although there were some teething problems early on they still worked fairly well. One boat HMAS Wollongong ran aground near Gabo Island when whe was attempting to shelter from heavy weather. They exceeded their design life by six years because there were no replacement vessels available and their services were in demand

Overall the Fremantle class was quite good however in retrospect it was seen that they were a little small for the ideal.

  • Number built - 15
  • Complement - 23
  • Length = 42m
  • Displacement = 220t
  • Durability = Exceeded design life by six years
  • Status = All have been decommissioned


Armidale Class

  • Displacement, Tons: 270
  • Dimensions, Feet (metres): 184.6 29.5 10.0 (56.8 9.0 3.0)
  • Main Machinery: 2 MTU 4000 16V diesels; 6,225 hp (4.64 MW); 2 shafts
  • Speed, Knots: 25. Range Nautical Miles: 3,000 at 12 knots
  • Complement: 21
  • Weapons: 1x25 mm Rafael M242 Bushmaster, 2 x 12.7 mm Machine Guns
  • Habitability is substantially better than the current Fremantle Class Patrol Boats.

  • Separate additional accommodation for up to 20.
  • Conduct all tasks up to the top of sea state 4 (2.5m waves).
  • Conduct key surveillance tasks up to sea state 5 (4m waves).
  • Continuous speed 25 knots in sea state 4 (waves to 2.5m) for 24 hours.
  • Range 3000 nautical miles (with a 20% fuel reserve) at a cruise speed of 12 knots.
  • Capable of being deployed for up to 42 days



Problems with the Armidale Class Patrol Boats (ACPB)

The Armidale class is a good design, however they have been asked to do much more than they were designed for. Thanks to the asylum seeker issue one ACPB is stationed at Christmas Island all the time. They are often asked to travel at very high speed in rough conditions to save the lives of overcrowded leaky vessels in rough seas. Additionally their radar is a little limited and a superior radar would give better detection ranges. Furthermore there have been cracks in at least three ACPBs, probably due to the huge amount of use they have had and the conditions in which they have to operate. Maximum speed is rated at 26 knots, but my guess is the real figure is a fraction higher.



What sort of Patrol Boat does Australia need

The need for Patrol boats is not going to go away. However sophisticated aircraft can be, they cannot interdict other ships and boats. In short they cannot make them stop and search their holds to see whether they are law-abiding or otherwise. Now there is a saying that steel is cheap and air is free, thus building a larger ship does not necessarily mean a large increase in cost. However the larger ship requires bigger engines to achieve the same speed, resulting in higher fuel use, higher capital cost and also docking space can become very problematic

What would be the requirements of our ideal replacement patrol boat

  • It would have to be fairly fast to interdict boats (35 knots plus)
  • Have good sea keeping
  • Have a good speed in a sea states 4 and 5
  • It would have a small gun forward
  • It would have a helicopter pad aft, though no hanger
  • Would have spare area for guests
  • Deploy two large RIBs (rigid inflatable boats)

  • Probably be powered by diesel engines
  • Use existing technology wherever possible (no carbon fiber)
  • Be affordable
  • Ideally be a modification of an existing design
  • Have a long structural life
  • Have modest ongoing costs
  • Large enough to withstand very rough weather

Now we get to the hard part, trying to make a compromise between all the competing factors. We want a fast, affordable boat, with a good surface search radar, ideally we also want a helicopter pad for taking off injured crew or vertical replenishment or aerial reconnaissance. We definitely want superior sea-keeping, habitability and ideally range and endurance. (stay at sea longer). One way would be to go very large like an OPV. The trouble with this route is that it can lead to very expensive boats. There is the real chance that one OPV would cost more than the entire ACPB fleet in terms of initial cost, not to mention the problems of trying to find docking space in northern ports.

Another route might be to go to a slightly enlarged version of what we already have. Now Australia has progressed from 146t boats to 220t to 270t. In each and every case it can be seen in retrospect that however good and cost effective the boats have been, they have all been a little too small than the ideal for their roles. Now we know that going a bit larger has fairly low downsides in terms of intitial cost. Now we could try for say a 350t boat but we risk the chance that it too will be a fraction too small. In my opinion we should 'bite the bullet' do it right and build much larger patrol boats, in the region of 600t. This is explained further below

600t the ideal size, explaining why

Now we could perhaps go for a boat without a helicopter pad, but that reduces flexibility. Additionally a smaller vessel will have trouble achieving higher speeds in a reasonable sea state. If we seek high transit speed, good habability, good seakeeping combined with the flexibility of a helicopter pade, then we really need to enlarge our vessel to 600t

The advantages of a 600t patrol boat over a 270t patrol boat can be summarised below

  • Has more interior volume and better crew habitability
  • Can maintain a higher speed with for a given sea-state
  • Can operate in larger sea-states
  • Has a longer structural life
  • Operate further from shore

  • Can have a much, much longer structural life
  • Give a more comfortable ride in rough seas
  • Can stay at sea longer
  • Can deploy a small unmanned helicopter
  • Can land larger naval helicopters for short periods

The advantages of several 600t patrol boats over fewer 2000t offshore patrol vessels
  • Be cheaper to run
  • Have a lower capital cost
  • Be in more than once place at once
  • Better fuel economy
  • Easier to find docking space for

  • Would need a smaller crew
  • Is a relatively simple vessel
  • Can be used for mundane tasks without taking larger vessels from important tasks
  • Have comparatively few expensive electronics that need maintenance and upgrades



What the Navy wants to do, and what I think they should do

Now the Navy has a plan. It kinda goes something like this. The eight Custom Bay class boats will be replaced with larger 58m Cape Class Patrol Boat. Max speed will only we 25 knots. It will be a fraction longer than the ACPBs. Next the ACPBs will be replaced with something called SEA 1180 vessels.

Now these SEA 1180 vessels are meant to be a class of 20 vessels using a common hullform for a hydrographic research vessel, MCM vessel and an OPV. Size will be up to 2000t. They will be fitted with a helicopter pad but no hangar. The trouble I see with this is that I suspect the Navy will see a 2000t OPV and deem that it is essential to fit it with SSMs, SAMs, ECM equipment, sonars, torpedos, CIWS etc etc. The unit cost will no doubt be best part of 400 million dollars. No doubt they will attempt to disguise the unit cost by combining all the vessels into one large program.

In my opinion the Navy should do the following

  • Build a commom MCM and Hydrographic reseach ship at 2000t to however many units needed
  • Build four 2000t OPVs with a helicopter hangar and deck, using the same 2000t hull
  • Build ten 600t patrol boats
  • Deploy a small helicopter to these OPVs, a helicopter that can land on the 600t patrol boat (eg Bell 429)
Such a mix of vessels would be very flexible, cost effective and durable. The larger OPVs could act as motherships for the smaller vessels, to accept guest transfers etc. Small Dauphin sized helicopters could operate between the OPVs and the patrol boats. The capital cost of ten 600t patrol boats would be only 400 million dollars, which works out at less than 15 million dollars per year when divided by a 30 year hull-life. Operating costs of the larger OPVs would be minimised by giving them an austere armament and modest max speed. Operating costs of the smaller 570t patrol boats would be minimised by simple armament and the long lead time required until they need replacing



Designing our ideal 600 tonne patrol boat

Option 1 - Take a slightly smaller design and scale it up

In this case we might look for a 550t patrol boat and scale it up slightly. It so happens that such a vessel does exist in the modern Turkish FAC the Kilic Class

  • Displacement: 552t
  • Length: 62.4 m (204 ft 9 in)
  • Beam: 8.6 m (28 ft 3 in)
  • Draught: 2.82 m (9 ft 3 in)
  • Propulsion: 4 MTU diesel engines 15,120 bhp (11.27 MW) 4 shafts
  • Speed: 40 knots (74 km/h; 46 mph)
  • Crusing ability: 24 knots in sea state 5

And what would out 'modified' vessel look like, well perhaps something like this, original craft at top, a crude modifed design below. Note that unit cost is around 40 million dollars. Removing the missiles would save money, but having them built in Australia would add money, thus a rough estimate of the same 40 million dollars unit cost seems fair

Note that the modifications include

  • Raising the foredeck a little
  • Removing the missiles and guns aft,
  • Adding a large helicopter deck
  • Adding two large RIBs amidships
  • Note the high speed, max 40 knots, and sustained 24 knots in sea state 5
  • Overall a good large, fast and capable patrol boat on 550 to 570t



Below, a slightly wobbly drawn modified design, a bit rough but you get the idea. No I will win no prizes as a graphic artist

Option 2: Take a slighty larger design and scale it down

To do our sketch we are going to cut corners. What we are going to do is look for a 600t boat that is similar and see if we can use that as our base. Now does such a vessel exist that could be our starting point. Well the answer is yes, and the place we have to look at is in of all places Ecuador.

Ecuador has a family of corvettes called the Esermelda class, some particulars are

  • Propulsion - 4 diesels giving 20,400shp
  • Construction - steel hull, designed and lauched in Italy
  • Launched 1982-1984
  • Max speed - 4 diesels for 37 knots
  • complement 51
  • dimensions 62.3 x 9.3 x 2.9m

  • Sonar - 1 hull sonar
  • Displacement 685t full load
  • Range at 12 knots - 7040km
  • Range at 18 knots (33 km/h) is 2,300 nautical miles
  • Aircraft capability, pad for small helicopter
  • Armaments, Exocet SSMs, two triple torpedo tubes, Albatros SAM, 76mm DP gun, twin 40mm gun



Now the first thing to notice is that this class has a lot of unneccessary equipment that could be removed. Removing this equipment would reduce weight and allow for a smaller craft. Now lets see what we can remove, given that the task for Australian patrol boats is to act as patrol boats, and not as small corvettes. It should be noted that we are mainly looking at the hull here, not the equipment onboard.

Items we could remove and then determining vessel displacement

  • The two triple Mk 32 torpedo tubes saving 3.5 tonnes (1750kg each loaded)
  • The hull mounted sonar - say 300kg
  • The four MM40 Exocet SSM - approx 5 tonnes (2.7 tonnes for missile, 2 tonnes for launchers)
  • The aft twin 40mm guns - approx 6 tonnes (estimate)
  • The 8 cell Albatros SAM, - estimate 6 tonnes - missiles 8 x 225kg, launcher and radar say 4 tonnes
  • One of the four 5000hp MTU diesels, gearbox and shaft - approx 18t (15t for engine and gearbox)
  • Control equipment for sonar, SSMs, SAMs - estimate 10t

Now given the above ommissions we could save 47 tonnes of weight. Additionally their would be other savings in that the hull would not have to be as large to carry this extra weight, allowing for a finer and lighter hullform forward that in turn requires less power to achieve a set speed. Now we have a much, much less cluttered hull. This could be accomplished by using fewer engines and/orlower powered diesels, also reducing weight. On the upside we might have to strengthen the helipad to accommadate the occasional deployment of a larger helicopter and also deploy larger RIBs. It should be noted that by removing all these weapon systems would reduce the need for crew, also lowering costs and weight. What we would be left with is a large seaworthy hull, with lots of space which would give plently of room for a crew of about thirty.

It thus seems very reasonable that we should be able to achieve our capacity, seakeeping, endurance, speed and range requirements fairly easily on a 600t hull.



Estimated specifications for proposed vessel as shown above

  • Propulsion: 4 diesels for 15,000hp giving 32 knots
  • Dimensions: 63m x 9.6m x 2.5m
  • Displacement: 600t
  • Aircaft: Capable of landing 5t helicopter
  • Designed for structural life: 30 years
  • Better motion in seaway compared to Armidale class
  • Short term accommodation for 120 evacuees



Option 3 - Modify the Tenix 56m Search and Rescue Patrol Boat


Specifications of the Tenix 56m Search and Rescue boat

  • Name: San Juan Class - 4 built for the Phillipines Coast Guard
  • Displacement: 560t
  • Dimensions: 56m x 10.55m x 2.5m
  • Propulsion: 2 MTU diesels totalling 11,000hp
  • Ability to survive in seastate 9
  • Max Speed:26 knots
  • Max sustained speed in seastate: 12knots in seastate 4
  • Features: short term accommation for 300 evacuees
  • Helicopter Facilities: Landing for 4.7t helicopter


Obviously this craft has some excellent features, most notably the huge temporary accommodation capability, and the helicopter pad. The downside of this craft seems to be its relatively slow speed, especially when compared to the Kilic FAC. Of course a FAC really needs fast speed to do its job, whereas for a SAR it is not essential to go quite as fast. However a higher transit speed, especially in a moderate seastate would be most welcome.

Extra speed could be obtained by the following changes. Increasing engine power from 11000hp to 15,000hp. Reducing beam from 10.55m to 9.7m, increasing hull length from 56m to 62m, increasing dispacement from 560 to 600t. Such changes would make a vessel with capabilities much closer to the FAC in terms of speed. The downside of course is that the reduced beam means less topweight can be carried, thus superstructure and hence internal volume is much reduced. However the vessel would still be much, much larger than the existing Armidale class (more than double), have better seakeeping. A rough estimate is that 100 evacuees could be carried for a short while, a very very useful capability.



Propulsion, engine power, hullsize, seasate, speed etc

A quick note about propulsion. Speed vs power is not linear, it tends to follow a parabolic curve such that doubling the speed requires a quadrupling of power, thus the extra few knots of speed can demand much greater power. Additionally a fuller squatter hull will generally require more power for a given speed than a sleeker finer hull. Using a finer hullform and hence an 85t reduction in displacement whilst retaining overall length would assist with speed, it seems quite reasonable that such a hull could be powered to 38 knots with 15000 shp. Now ideally a hull speed prediction program will give better answers, I am fairly confident that this speed stated speed could be attained from the lower power quoted. A little aside the Turkish 550t Kilic FAC are quoted at 40 knots and maintain 24 knots in seastate 5 (2.5 to 4m waves). The ACPB has an official maximum speed of only 26 knots.

One good method for determining hull speed is to use a hullspeed calculator.

I have tried the following calculator and found it very accurate even up to large patrol boats described on this page. Of course it does not delve into seastate, where for example a boat with 40 knot max speed is limited to 24 knots in seastate 5. The calculator that I like can be found HERE


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