Design question relating to Austal MRV...

[Todjaeger]

Yes, I have been doing something dangerous again, I have been thinking...

The question is primarily targeted for those members with maritime design/engineering experience, though imput from those with nautical experience is also very welcome. Please keep in mind I have no experience of my own aside from knowing that unless its a sub, sinking is bad...
Anyway, here goes the lead-up, the questions are at the end.

The MRV Corvette listed on the Austal site, click on Austal Trimaran Technology Brochure to view the specs, to me is an interesting concept.

More detailed discussion on the pros and cons can be found in the RAN thread, but I will just do a quick recap as I understand it.

The MRV Corvette specs are:
Length: 78.5m LOA
Sprint speed: 25+ kts
Range: 6,000 n miles
Deadweight: 320 tonnes
Mission deck: 540 sq m
Flight deck & hangar: can handle an NH-90 helicopter

The mission deck can be used as a flexible Ro/Ro mission or logistics deck
The flight deck & hangar can accomodate a multi-mission medium helicopter
The design can accomodate packaged mission systems modules.

As such, it is a fairly flexible little ship.

The downsides of the design, in no particular order are:
1. The armament is a 25mm Typhoon mounting, unsuitable for anything except some ship self-defence and patrolling, insufficient for a warship.

2. The hull is an aluminum trimaran hull built to the HSC code, restricting the ability (or suitability) of the vessel to operate more then 8 hours travel from port, as well as seaworthiness in open ocean or rough seas.

3. The range of the vessel has been questioned in terms of what the crusing speed is to achieve that range. The implication is that a trimaran hull is not able to achieve that range with the listed sprint speed, and traditional monohulls are able to achieve that same range while able to transport significantly greater amounts of equipment.

As I have mentioned before in the RAN thread, IMV such a design would likely serve quite well in greenwater environments like those found around Indonesia, Malaysia, the Philippines, Nigeria (for the delta area) and possibly some of the South Pacific island nations like Fiji, the Solomons, etc. Whether or not the nations mentioned could afford the design and/or adequately maintain them is a completely different issues. The other part of the concensus was that the inherent limitations of the design in terms of available areas of operation meant that it would be unsuitable for use by the RAN.

Okay, having gone through all that, here are the two questions.

1. If the design was constructed from mild steel, or whatever type steel is normally used for ship construction, would that improve the suitability of the design for use by the RAN and/or similar nations?

2. Would changing the design to a traditional monohull, possibly in conjunction to a change to steel construction, improve the suitability for use by bluewater navies?

3. Is there a use for small MRVs in the range of 80-100m?

I am sort of seeing this as being an Absalon-Lite type of vessel, some combat capabilities, the ability to transport and support a land force, deliver humanitarian aide, etc.

-Cheers

edit: Thought of additional questions that I had meant to ask.
AFAIK one of the features of multi-hull vessels is that they are comparatively broad-beamed relative to their length when compared to the length/beam ratio of a monohull. If the design were to be changed to a monohull, would it make sense to keep the same dimensions, and if not, what would likely need to be changed? As an addition to that, would the number of decks above the waterline have a negative impact on the vessels seaworthiness? I would think that concerns could arise over the design having a high centre of gravity, with having a Ro/Ro mission deck and then a separate flight deck above that.

 

[alexsa]

Yes, I have been doing something dangerous again, I have been thinking...

.......... the inherent limitations of the design in terms of available areas of operation meant that it would be unsuitable for use by the RAN..

Agree with all that while noting that the product wouel be very useful in the sheleter waters (archpaleagic) over realtively short ranges but for the cost is less effective fro the RAN than other options IMV given our operating area. it is also worth noting that Austal realy are at the cutting edge and produce and exceptional fast ferry design.

Okay, having gone through all that, here are the two questions.

1. If the design was constructed from mild steel, or whatever type steel is normally used for ship construction, would that improve the suitability of the design for use by the RAN and/or similar nations?

2. Would changing the design to a traditional monohull, possibly in conjunction to a change to steel construction, improve the suitability for use by bluewater navies?..

The problem is the hull is designed around high speed operations and has a limited scope for varaition in draft. Either mild (quite heavy) or HT steel (less heavy) construction will still be heavier than aluminium and will result in less carrying capacity if you wished to keep the vessel at the same relative displacement on the same type of design. There is quite a bit of structure to give the sea frame the strenght it requires and ths wouel still need to be replicated in steel.

For the same cost you could get a new quite a large RO-RO hull. As an example a brand new vehicle Carrier with about 26000 m2 of garage space will now cost you in the order of 80 to 100 million USD (cost have really gone up recently) with a service speed of 21 knots thsi provides an enomous uplift capacity with a crew of only 21.

Add a bit more money and the design could be modified to military needs. As an example a livestock carrier (beleive me these a complex vesels) built on the basis of a 24000m2 car carrier comes in at 125 million USD (with spares)

3. Is there a use for small MRVs in the range of 80-100m?

I am sort of seeing this as being an Absalon-Lite type of vessel, some combat capabilities, the ability to transport and support a land force, deliver humanitarian aide, etc.

I like the Abslon but think that if provides a decent frigate with too little capability in other areas for the cost, everything is a compromise. IMV we would be better spending some of this money focusing on builting on current project to build up our tier one assests (AWD and ANZAC/ANZAC replacement) noting there are economies of scale. For the other roles a more specialised vessel could provide could do the job better such as a RO RO sealift support vessel and purpose built partrol asset. For patrol some there is certainly a need for ice class OPV type vessels. For sea lift/ disaster relief etc a conventional vessel appears to have better economics, i.e:

Convenrted RO-RO design with:
1. Arrangement cut down by one deck and large helo flight deck added with superstrucutre off set to one side (you wouel need to lower the CoG if a flight deck was to be added).
2. Ability to carry lighterage equipment added (providing a discharge cpacity without port facilties)
3. A reasonable LCM8 (or its replacement) carraige facilty added.

If such a vesel could provide 20000m2 of garage space with 12500 tonnes of DWT with a service speed of 19 to 21 knots istwould be very capable and would match the effective operating speed of out other assets (noting the tier 1 will escort at this speed in any case). Even at 150 million USD this would be a steal.

http://www.shippingtimes.co.uk/itm105_ray-car-carrier.htm

I suspect the MRV is going to cost a great deal more than the ACPB which from memory were in the order of 40 Million AUD a copy. With a DWT in the order of 300 tonnes you need a lot of MRV to provide the same capability.

The MRV lighter draft offers advantages (off set by the fact it is quite beamy) but this can be off set by helo capcity and lighterage equipment noting the MRV needs a port to disharge in which is quite a limitation

-Cheers

edit: Thought of additional questions that I had meant to ask.
AFAIK one of the features of multi-hull vessels is that they are comparatively broad-beamed relative to their length when compared to the length/beam ratio of a monohull. If the design were to be changed to a monohull, would it make sense to keep the same dimensions, and if not, what would likely need to be changed? As an addition to that, would the number of decks above the waterline have a negative impact on the vessels seaworthiness? I would think that concerns could arise over the design having a high centre of gravity, with having a Ro/Ro mission deck and then a separate flight deck above that.

See above. The seaframe hull is quite stable given it beam but that has issues with hull strength in a seaway and will subject to greater torque due to is width and separated areas of buoyancy. The stablaised long thin monhull (which is the sea frame) is much better than the catamaran opiton but will wtill be more limtied than a conventional monohull in more challenging conditions.

 

[Todjaeger]

Thanks for the comments Alexsa.

Let me clarify my thinking a little bit and then if you could give me your opinion on that it would be appreciated.

What I was thinking of was taking some of the features of the Austal MRV like the Flight deck & hangar, as well as the Ro/Ro nature of the Mission deck and having that applied to a similarly dimensioned steel monohull.

Think of something like the HMS Clyde, with a full helicopter hangar instead of just the platform, and with a Mission deck able to accomodate landing some vehicles, etc. Then perhaps incorporating some of the Standardflex design elements found in the Danish Absalon or Flyvefisken-class vessels for the option of improving the offensive and defensive capabilities as needed, and perhaps ice-strengthening the hull as well.

Such a design, if viable, could be used to replace the Oceanic Viking on EEZ & fishery patrols in the Southern Ocean where an embarked helicopter and overall light armament (25mm cannon) would be sufficient. It could then be reconfigured and troops and/or humanitarian aide could loaded to assist in a regional crisis, be it natural disaster or breakdown in order like occured in the Solomons. It could also be re-roled into a combatant of sorts by loading modules (via SF300) with improved weapons, etc.

The real question would be if an ~80m x ~ 14m vessel displacing ~1,700 tons could be viably put together with these features, and if so, would such a vessel be useful. I am not sure if such a vessel would be large enough to carry and launch and LCM8 or similar, and if it cannot, would that mean it likely could not be used to land troops, vehicles or supplies in the event of a disaster or conflict in the region? Also, even if that was not an issue, is 540 sq m of deckspace enough for a useful number of vehicles? I am not thinking of using this as a landing ship, rather being able to deliver a detachment of peacekeepers or aide workers in a crisis and then be able to loiter in an area to provide support to the detachment via floating hospital/med bay, heli support, comms etc. For major disasters, then the Canberra-class LHD would be dispatched once they are in service, however the usage I would consider for what I have in mind is for smaller issues, or if there are a number of events where Oz and/or NZ needs to have a supporting presence in the region, yet larger vessels are not needed.

-Cheers

 

[Jezza]

how about this design

 

[Todjaeger]

how about this design

Interesting image. Not a ship designer or in any maritime industry myself, but there are a few things which strike me as problematical with the design itself.

It is hard to get an idea of just how large the vessel is supposed to be but I would guess at ~80m oa.

I do not see a funnel on the vessel, though it is possible the vessel vents the exhaust at the waterline. However, having a Coastguard vessel do so does not make sense to me. That sort of IR suppression would be more appropriate to a warship as opposed to a civil or paramilitary patrol vessel.

Another area I question is just how seaworthy the design is supposed to be. The superstructure seems to be awfully open and I would have concerns about functional this many openings would be in rough or cold weather. It appears that from the stern forward to beneath the heli platform amidships is exposed.

Another item is that there appears to be a well dock of sorts at the stern, though I cannot tell for what. I would think it too small for an LCM, yet too large for a RHIB, not to mention, what would be loaded onto it? There does not appear to be a vehicle deck and the vessel has little superstructure apart from the bridge and forward area.

Lastly, at least for what I have been envisioning, the model only has a heli platform, not a hangar. While this would allow landing and takeoffs between other vessels and/or shore facilities I am uncertain how functional a helicopter could be kept on such a platform during a patrol in the Southern Ocean or any other operational area away from other vessels or facilities.

Still, it does get one to think.

-Cheers

 

[StevoJH]

Interesting image. Not a ship designer or in any maritime industry myself, but there are a few things which strike me as problematical with the design itself.

It is hard to get an idea of just how large the vessel is supposed to be but I would guess at ~80m oa.

I do not see a funnel on the vessel, though it is possible the vessel vents the exhaust at the waterline. However, having a Coastguard vessel do so does not make sense to me. That sort of IR suppression would be more appropriate to a warship as opposed to a civil or paramilitary patrol vessel.

Another area I question is just how seaworthy the design is supposed to be. The superstructure seems to be awfully open and I would have concerns about functional this many openings would be in rough or cold weather. It appears that from the stern forward to beneath the heli platform amidships is exposed.

Another item is that there appears to be a well dock of sorts at the stern, though I cannot tell for what. I would think it too small for an LCM, yet too large for a RHIB, not to mention, what would be loaded onto it? There does not appear to be a vehicle deck and the vessel has little superstructure apart from the bridge and forward area.

Lastly, at least for what I have been envisioning, the model only has a heli platform, not a hangar. While this would allow landing and takeoffs between other vessels and/or shore facilities I am uncertain how functional a helicopter could be kept on such a platform during a patrol in the Southern Ocean or any other operational area away from other vessels or facilities.

Still, it does get one to think.

-Cheers

I have a feeling that it might be a BAe proposal for an Indian Coast Guard Vessel. It definitely looks......unique....

 

[alexsa]

I have a feeling that it might be a BAe proposal for an Indian Coast Guard Vessel. It definitely looks......unique....

The image is a Rolls Royce design. In this case it is a derivation of the UT700 serios with a claimed 20000nm range and the LOA in excess of 100m and a speed of over 20 knots. It also ahs the ability to tow damaged vesels rescue survivors (wiht a 100 man survivor facility) all on a crew of about 25.

The indian vessel is a UT517 hull and come in at 94m or there abouts. Still a nice vessel wiht a 6000nm range and a speed of 20knots.

http://www.rolls-royce.com/marine/systems_solutions/ship_design/naval_support/coastal_patrol.jsp

These ships are quite beamy and very stable being based on an North sea offshore vessel. If anything they are likely to be a bit too stiff but that is quite easilly fixed.

 

[alexsa]

Thanks for the comments Alexsa.

Let me clarify my thinking ...

The real question would be if an ~80m x ~ 14m vessel displacing ~1,700 tons could be viably put together with these features, and if so, would such a vessel be useful. I am not sure if such a vessel would be large enough to carry and launch and LCM8 or similar, and if it cannot, would that mean it likely could not be used to land troops, vehicles or supplies in the event of a disaster or conflict in the region? Also, even if that was not an issue, is 540 sq m of deckspace enough for a useful number of vehicles? I am not thinking of using this as a landing ship, rather being able to deliver a detachment of peacekeepers or aide workers in a crisis and then be able to loiter in an area to provide support to the detachment via floating hospital/med bay, heli support, comms etc. For major disasters, then the Canberra-class LHD would be dispatched once they are in service, however the usage I would consider for what I have in mind is for smaller issues, or if there are a number of events where Oz and/or NZ needs to have a supporting presence in the region, yet larger vessels are not needed.

-Cheers

Sorry, I was away hence the lack of response. A mild steel vesel of 80m plus wit the features of he MRV will weigh in at quite a bit more than 1700 tonnes I would suggest.

It is all a compromise. The MRV gives good volume but poor uplift (due to the light weight construction) while a mild steel hull would give you better up lift but posible less volume if you stayed with the 80 m limitation due to the narrower beam.

In other words the MRV maxes out on weight very quickly while a mild steel vessel of 80m with a beam of around 10m (quite beamy) would give less volume.

You would need to go for a longer hull (say 95m) and greater beam if you wanted to get near the volume with the advantage then being a large increase in mass that can be carried. (as an example the UT517 in my previous post can carry 300 tonnes of FO and 500 of recover oil alone..... the total dWT of the MRV is only about 300 tonnes)

Again what kit you fit (LCMs at 55 tonnes) that will also determine the design and capability of the ship. I think the reality is that on an 80 to 95m LOA you would only be looking at LCVP's if you wished to fit for a varaitey of other roles.