Royal Australian Navy Discussions and Updates 2.0

[Scott Elaurant]

My understanding of the physics is that the risk of cavitation in a submarine declines as the water depth increases. At deep depths the water pressure is such that the air bubbles that cause cavitation less easily form on the propeller, hence no cavitation unless at a higher speed. Propeller design and devices like impellers also reduce the risk of cavitation. See this video by H I Sutton which explains how impellers work.

So if an SSN goes down below say 150 metres depth, it can scoot along at over 30 knots with only its engine and hydrodynamic noise. Of course that is still a lot noisier than at say 10 knots, so that SSN would still easily be heard at tactical ranges by an enemy sub.

The fastest cold war subs (Soviet Alphas) reportedly could do over 40 knots. These days quick SSNs can probably do 35 knots, the fastest SSKs can do 20-25 knots for a short sprint. I have never heard of any SSN that could do 50 knots.

The point is that the top speed of an SSN (much less than 50 knots) is NOT useful for tactical pursuit of an SSK. But it is very useful for the SSN escaping fire or rapidly redeploying to another location if in deep water. This is one reaspon why SSNs like deep water.

 

[Meriv90]

Wasnt also to evade torpedos that normally travel at 30+knts? (Mu90 and Mk48)

 

[Bob53]

My understanding of the physics is that the risk of cavitation in a submarine declines as the water depth increases. At deep depths the water pressure is such that the air bubbles that cause cavitation less easily form on the propeller, hence no cavitation unless at a higher speed. Propeller design and devices like impellers also reduce the risk of cavitation. See this video by H I Sutton which explains how impellers work.

So if an SSN goes down below say 150 metres depth, it can scoot along at over 30 knots with only its engine and hydrodynamic noise. Of course that is still a lot noisier than at say 10 knots, so that SSN would still easily be heard at tactical ranges by an enemy sub.

The fastest cold war subs (Soviet Alphas) reportedly could do over 40 knots. These days quick SSNs can probably do 35 knots, the fastest SSKs can do 20-25 knots for a short sprint. I have never heard of any SSN that could do 50 knots.

The point is that the top speed of an SSN (much less than 50 knots) is NOT useful for tactical pursuit of an SSK. But it is very useful for the SSN escaping fire or rapidly redeploying to another location if in deep water. This is one reaspon why SSNs like deep water.

Nice explanation thanks.

 

[ASSAIL]

My understanding of the physics is that the risk of cavitation in a submarine declines as the water depth increases. At deep depths the water pressure is such that the air bubbles that cause cavitation less easily form on the propeller, hence no cavitation unless at a higher speed. Propeller design and devices like impellers also reduce the risk of cavitation. See this video by H I Sutton which explains how impellers work.

So if an SSN goes down below say 150 metres depth, it can scoot along at over 30 knots with only its engine and hydrodynamic noise. Of course that is still a lot noisier than at say 10 knots, so that SSN would still easily be heard at tactical ranges by an enemy sub.

The fastest cold war subs (Soviet Alphas) reportedly could do over 40 knots. These days quick SSNs can probably do 35 knots, the fastest SSKs can do 20-25 knots for a short sprint. I have never heard of any SSN that could do 50 knots.

The point is that the top speed of an SSN (much less than 50 knots) is NOT useful for tactical pursuit of an SSK. But it is very useful for the SSN escaping fire or rapidly redeploying to another location if in deep water. This is one reaspon why SSNs like deep water.

Very true, part of the “shoot and scoot”ops but the problem is that while scooting the boat is totally blind and deaf and noisy and has no idea what aerial ASW assets are present and they will be there after an attack.
The real advantage of speed is that SSNs can be used in an escort role, clear the route ahead of a force with a speed of advance in the high teens early twenties (knots), something impossible for a non nuke, leapfrog listen, leapfrog listen ad nauseum.

 

[Armchair]

The point is that the top speed of an SSN (much less than 50 knots) is NOT useful for tactical pursuit of an SSK. But it is very useful for the SSN escaping fire or rapidly redeploying to another location if in deep water. This is one reaspon why SSNs like deep water.

Also (and presumably of keen interest to RAN) SSNs can more easily keep up with surface task forces they are attached to (or arrive in advance of slow transports as per the Falklands War).

 

[Scott Elaurant]

Very true, part of the “shoot and scoot”ops but the problem is that while scooting the boat is totally blind and deaf and noisy and has no idea what aerial ASW assets are present and they will be there after an attack.
The real advantage of speed is that SSNs can be used in an escort role, clear the route ahead of a force with a speed of advance in the high teens early twenties (knots), something impossible for a non nuke, leapfrog listen, leapfrog listen ad nauseum.

Yes of course. That tactic was also how the HMS Conqueror closed on the General Belgrano during the Falklands War.

The UK, France and USA all regularly run an SSN to escort their carrier task forces for this reason. An Australian SSN would be very valuable used the same way to escort a Task Force grouped around the Canberra or Adelaide.

The Collins was a great SSK in its day, and is still very good. But when you look at the huge areas of deep ocean surrounding Australia, SSNs would be incredibly useful to the RAN both patrolling and as a deterrent IMO. No other warship could redeploy as quickly in any weather. Even for peacetime ISR, they would be invaluable.

 

[devo99]

On a bit of a random note. Does anyone here know the name of the old greenish grey paint the RAN used to use?
Would that be Haze Grey?

 

[Wombat000]

On a bit of a random note. Does anyone here know the name of the old greenish grey paint the RAN used to use?
Would that be Haze Grey?

Storm Grey.
current colour is Haze Grey. (unknown if it has an RAN variant feature to it?).

 

[devo99]

Seems like I may have mixed up Haze Grey and Storm Grey.

 

[spoz]

And a much better colour to blend in with sea and atmospheric conditions in our north than Haze Grey; but apparently the current paint, which is just about the same as the USN, has some sort of absorbent quality that, for some reason, cannot be added to Storm Grey. Seems more like a fashion thing to me.

 

[Going Boeing]

Kim Beazley appears to understand that situation that the RAN is now in - and WHY.

Australia’s disappeared surface combatant fleet | The Strategist

 

[Volkodav]

Th

Kim Beazley appears to understand that situation that the RAN is now in - and WHY.

Australia’s disappeared surface combatant fleet | The Strategist

It appears to be an update of his podcast with Contact last year and is still spot on.

We replaced nine, obsolescent, first line ships with three second line ships, and pretended eight small, third line ships were first line ships.

We needed twenty plus major combatants, in a benign strategic environment, planned for seventeen, dropped to eleven and now are looking at eight as we enter the most challenging strategic situation we have seen since the late 1930s.

There is now no doubt that Liberals, Labour, or Liberals should have ordered a minimum of an additional two Hobarts or a second evolved batch of at least three. Too late now.

It looks the only options are continue with at least five Hunters to the original config before switching to an FFG or DDG, as well as aquiringing something far superior to the Arafura.

 

[iambuzzard]

Th

It appears to be an update of his podcast with Contact last year and is still spot on.

We replaced nine, obsolescent, first line ships with three second line ships, and pretended eight small, third line ships were first line ships.

We needed twenty plus major combatants, in a benign strategic environment, planned for seven, dropped to eleven and now are looking at eight as we enter the most challenging strategic situation we have seen since the late 1930s.

There is now no doubt that Liberals, Labour, or Liberals should have ordered a minimum of an additional two Hobarts or a second evolved batch of at least three. Too late now.

It looks the only options are continue with at least five Hunters to the original config before switching to an FFG or DDG, as well as aquiringing something far superior to the Arafura.

Kim Beazley is a man who understood his portfolio when he was DefMin. We need more of his type of insight if we are to get our defence back on track.

 

[Volkodav]

Kim Beazley is a man who understood his portfolio when he was DefMin. We need more of his type of insight if we are to get our defence back on track.

I wish we had a system like the US where there is a politically appointed head or secretary, instead of ministers, who is not elected, but is not necessarily a career public servant or industry appointee.

That would see people like Beazley, Bishop (Julie, not the Rottweiler), aswell as former military, scientists, medicos etc. assigned to these important roles.

The public service returns to providing fearless, impartial, advice, instead of being yesmen looking for promotion.

 

[Reptilia]

Th

It appears to be an update of his podcast with Contact last year and is still spot on.

We replaced nine, obsolescent, first line ships with three second line ships, and pretended eight small, third line ships were first line ships.

We needed twenty plus major combatants, in a benign strategic environment, planned for seven, dropped to eleven and now are looking at eight as we enter the most challenging strategic situation we have seen since the late 1930s.

There is now no doubt that Liberals, Labour, or Liberals should have ordered a minimum of an additional two Hobarts or a second evolved batch of at least three. Too late now.

It looks the only options are continue with at least five Hunters to the original config before switching to an FFG or DDG, as well as aquiringing something far superior to the Arafura.

Someone on this forum may know whether or not Luerssen/Civmec have cut steel on opv 7 by now, would be a good indicator of future plans.
With the F110s way ahead of schedule in Spain and the Saudi corvette order almost complete, what are the chances we do a deal with Spain in the short term to enhance our capability before 2030?, Tasman Corvettes(Navantia, Civmec, Austal Collab) or Hobarts / F110 (built here, overseas or split) or a purchase/leasing of a current in service Destroyer like the F105 and upgraded along with our current hobarts.(if purchased)

 

[Todjaeger]

I wish we had a system like the US where there is a politically appointed head or secretary, instead of ministers, who is not elected, but is not necessarily a career public servant or industry appointee.

That would see people like Beazley, Bishop (Julie, not the Rottweiler), aswell as former military, scientists, medicos etc. assigned to these important roles.

The public service returns to providing fearless, impartial, advice, instead of being yesmen looking for promotion.

I do not wish to rain on anyone's parade, but the US system does make it distinctly possible for 'Yes men' to get assigned to important posts. The US has, so far at least, managed to not have one end up in an important post at a critical time, but it has been close at least a few times even quite recently. Not going to go into it further as it quickly would become the stinking quagmire that is current US politics.

 

[Volkodav]

Someone on this forum may know whether or not Luerssen/Civmec have cut steel on opv 7 by now, would be a good indicator of future plans.
With the F110s way ahead of schedule in Spain and the Saudi corvette order almost complete, what are the chances we do a deal with Spain in the short term to enhance our capability before 2030?, Tasman Corvettes(Navantia, Civmec, Austal Collab) or more Hobarts (built here, overseas or split) or a purchase/leasing of a current in service Destroyer like the F105 and upgraded along with our current hobarts.(if purchased)

We are laying up ANZACs because we don't have enough engineers, technical sailors and combat systems operators, how would we crew and support these ships that have significant equipment, logistical and training differences to current RAN ships?

A lot of the issues we have now are due to the lack of understanding by decision makers in successive governments over what is involved in acquisition and sustainment of capability, in particular personnel and staff recruitment, training and retention.

They honestly seem to assume any idiot off the street can do this work. It's probably because they predominantly come from backgrounds where any idiot could do what they do, sales, marketing, hr, union officials, political staffers, management etc.

 

[Volkodav]

I do not wish to rain on anyone's parade, but the US system does make it distinctly possible for 'Yes men' to get assigned to important posts. The US has, so far at least, managed to not have one end up in an important post at a critical time, but it has been close at least a few times even quite recently. Not going to go into it further as it quickly would become the stinking quagmire that is current US politics.

Fair call and I understand what you are saying. I just see it as a waste in this country when many of our most talented individuals are lost to public service when the government loses office or they retire from the military. Many others don't get to serve at higher levels because they never seek political office.

 

[Reptilia]

We are laying up ANZACs because we don't have enough engineers, technical sailors and combat systems operators, how would we crew and support these ships that have significant equipment, logistical and training differences to current RAN ships?

A lot of the issues we have now are due to the lack of understanding by decision makers in successive governments over what is involved in acquisition and sustainment of capability, in particular personnel and staff recruitment, training and retention.

They honestly seem to assume any idiot off the street can do this work. It's probably because they predominantly come from backgrounds where any idiot could do what they do, sales, marketing, hr, union officials, political staffers, management etc.

The Tasman class was said to address some of those crew shortages is why I mentioned it, not in addition to the Anzacs but as a short term replacement before Henderson is upgraded and a greater capability acquired.

 

[Stampede]

Someone on this forum may know whether or not Luerssen/Civmec have cut steel on opv 7 by now, would be a good indicator of future plans.
With the F110s way ahead of schedule in Spain and the Saudi corvette order almost complete, what are the chances we do a deal with Spain in the short term to enhance our capability before 2030?, Tasman Corvettes(Navantia, Civmec, Austal Collab) or Hobarts / F110 (built here, overseas or split) or a purchase/leasing of a current in service Destroyer like the F105 and upgraded along with our current hobarts.(if purchased)

All good suggestions and questions however we are all on a holding pattern pending the outcome of the Naval Review.
Hopefully an anounced this quarter.
APDR suggested by late Feb.

We wait in the public domain as do many manufacturers eager for a piece of the Naval pie.

Land mark document or anti climax.
We'll know soon enough.

Cheers S