ArmChairCivvy wrote:- why would the crewing, in the patrol variant, be much higher than in the Hollands?
My concern is mainly with damage control, the Absalon hull is vastly bigger than the Holland class. The Holland class is great example of what an OPV can be and is often compared to our very own RB2's. At 3750t, almost twice the displacement of the RB2's I'm not sure it's a fair comparison although they are undoubtably much more capable in the global patrol role mainly due to the embarked helicopter. With a 16m beam the Hollands are 2.5m wider than the RB2's and at 108m, a full 18m longer.
Game, set and match to the Hollands then. Not quite, their top speed is a mere 21.5knts, that doesn't compare well to the RB2's 25knts. The Holland class make up for this lack of speed with the FRISC rigid inflatables which are capable of 40knts and can be deployed quickly whilst still underway via the stern ramp. When combined with the embarked helicopter it all makes for a potent patrol package for low threat level environments. (Note, 76mm main armament and 30mm secondary)
In the HADR role however the Hollands are much more limited, a small number of ISO containers can be stored under the flight deck and although the deck mounted crane is a great addition, due to the lack of storage space it's unlikely to have much to unload unless the small craft or the helicopter is not carried (Note, the ISO and pallet sized deck hatches are clearly visible in the graphic)
So is 25knts really necessary for the 'Patrol' role?
Could an MHC vessel with a top speed of 21knts also perform well in the patrol role if it carried high speed rigid inflatables and embarked a helicopter?
donald_of_tokyo wrote:I do not think common hull is so important......
Building ships with hull design specific to their tasks will be more important.......
Make them common ONLY IF their requirement it very similar......
Personally, I think it's worth exploring, if it was possible to design a common hull form for the T31,MHC and Global Patrol vessels it would undoubtedly save money and may mean more hulls in the water but I agree, it must work for each specific role.
Are the specifications for the 3 variants really that different?
The latest MHC concept, the Venari 85 is pretty wide beamed to ensure stability when deploying the increasingly bulky MCM equipment. Would a vessel with an 18m to 19m beam be suitable for the MHC role, I would say it may even be preferable. The narrow beam of an OPV is one of the reasons BMT uses to suggest that OPV's are less than ideal for the MHC requirement.
So is a 19m beam suitable for the T31?
BMT and Babcock must think so as their Arrowhead 120 concept has a 19m beam. So if the 19m beam is suitable for the T31 and MHC vessels surely it would be much too wide for the Patrol role?
In the past the answer would be 'much too wide' but looking ahead I'm not so sure.
In my opinion going forward all RN vessels will have to be as multipurpose as possible. For example, why base a Bay in the Carribean when a cheap multipurpose patrol vessel with an embarked helicopter(s) could perform the patrol role more efficiently and also excel in the HADR role if needed with only half the crew allocation. These multipurpose global patrol vessels could patrol and then provide the first response to any humanitarian crisis and thereafter the Bay's could be dispatched if the situation is deemed serious enough to warrant that level of response.
How is it possible to combine all these various requirements in a single hull form?
Caribbean wrote:I certainly meant that we should be looking at assembling ships from common "component blocks", so that, for instance, two different variants might have (as an example) common bow and amidships hull and superstructure sections, but different aft superstructure blocks and stern.
In my opinion the modular construction process opens up a world of possibilities. It's quite simply the only way 3 variants on a single hull form is even remotely possible however unfortunately I don't think the Absalon hull form is suited to a modular construction process. It could easily be built in blocks but if for example a 105m and 120m version was required it would probably lead to a complete redesign of the hull form.
Caribbean wrote:I I would suggest that it's probably not necessary to try to shrink the design down to 100m as you discussed.....103-105m would seem the minimum desirable.........If you couple that with reducing the beam slightly as well (for all variants), could we arrive at a design that could maintain 25kts without huge expenditure?
In my previous post I proposed roughly 100m, within 5m or so. I have been advocating a 105m vessel with embarked helicopter for the MHC programme for a while now so let's proceed on that basis and look at the 105m and 117m to 120m variants.
When shrinking the Absalon by 20m down to 117m it quickly becomes apparent that the tall superstructure is likely to cause problems with stability. As this amount of superstructure is not required for lean crew allocations I have also reduced the height of the bridge and the superstructure aft of the bridge to lower the CoG.
It hard to know how much of a hull redesign would be required for a 117m Absalon without tank testing but on paper it looks pretty good. These images are a pretty rough attempt to illustrate what these shortened Absalon concepts would look like. With the option of a Mk45 main armament, lots of space for VLS cells forward of the bridge, twin Merlin capable hanger and over 50m of Flex deck what's not to like for the T31. The reduced height of the superstructure helps balance the shorter design and in my opinion this looks like a much better option than any of the current T31 concepts.
The 105m concept is as expected much more problematic. I feel this would definitely require a complete hull redesign but the general concept remains sound. Although it's clear that at 105m the hull form is all wrong, it's not without its charm
The overall configuration of 105m length, 19m beam, twin hanger and 50m of flex deck is clearly viable if built on a suitable hull. This configuration turned out more successful than I initially expected.
So if not the Absalon hull, what else might be suitable?
The Arrowhead 120 hull form looks perfect for the modular construction process but the easiest way to explore the modular 3 variant concept is with the Damen Crossover. The Damen design adds a welcome bulkhead and divides the Flex deck into 2 separate spaces. This is probably preferable to the simple RoRo Absalon design. The central multipurpose space could be configured in various different ways depending on the deployment whilst the aft amphibious compartment could house the small craft up to the size of LCVP's. The port and starboard side doors would allow simultaneous deployment of MCM equipment and the deck crane and associated hatches in the flight deck could also aid unloading.
With the modular build design almost anything is possible but the graphics below give an indication of the ease that different variants can be produced with maximum commonality and minimum redesign.
The 105m, 19m beam, 4000t MHC and Patrol variant. Single spot flight deck, twin helicopter hanger. This looks much better balanced than the Absalon design whilst maintaining the benefits of the flex deck concept.
The 120m, 19m beam, 4600t T31 or Patrol variant. Double spot or Chinook capable flight deck, twin hanger and increased Amphibious capacity. Lots of space for VLS cells forward of the bridge. In the Patrol configuration, equipped with up to 2 Merlins, 4 LCVP's and vast amounts of HADR supplies, this variant could be a true multipurpose vessel. With up to 2 Wildcats and multiple high speed rigid inflatables these vessels could also excel in the Patrol role.
As an example of how versatile these modular vessels can be, this is the 147m, 5600t Tier 1 Frigate variant. Again lots of space for Mk45, ample VLS cells, 2 landing spots or Chinook capable flight deck, twin Merlin Hanger and over 70m of Flex Deck or multipurpose space. If this hull form and propulsion system was optimised for ASW and combined with 2087 sonar, it could be a very useful multipurpose platform and a good benchmark for any second batch of T31's. .
I am not necessarily advocating the Damen Crossover or the Absalon designs as the basis for the T31 or MH(P)C programmes but the general concept of the modular reconfigurable design is certainly worthy of serious consideration. It is a truly versatile concept especially when designed from the outset to prioritise maximum modularity and commonality across the variants.
Obviously cost is the determining factor but is it possible to produce two different build standards within the same design? For example the Patrol variant to be built to OPV standards with watertight doors and standard bulkheads and the T31 variant to be built to full naval standards with watertight doors and reinforced/blast proof bulkheads. What standard should the MHC vessels be built to?
Until it is confirmed how the MHC vessels will operate in future it is difficult to identify the most suitable design. For example the Op Kipion MCM deployment normally comprises 2x Hunt class, 2x Sandown class and 1x Bay Class. That's over 250 crew and 5 vessels including the Bay.
When the MHC ships enter service will it still be 4 MHC vessels acting with a mothership or will it be 2 or 3 MHC vessels with embarked helicopters acting as a team without a mothership?
If the Kipion MCM deployment evolves into 2 self sufficient 4000t MHC vessels with a combined crew allocation of 120 to 140, fully capable of self defence and even possessing some offensive capabilities via the embarked Wildcats it could prove to be a significant step up in capability as well as provide a long term financial saving for RN.
The Global Patrol Vessels could also be a real game changer for RN, a cost effective patrol vessel designed to provide security in low threat areas that is also fully equipped to provide rapid HADR assistance if required. A true multipurpose vessel.
If the current MCMV's were replaced with 12x MHC/Patrol vessels along with the 5x T31 vessels it would make for a healthy order of 19 ships.
8x. 105m MHC variants
4x. 105m Global Patrol variants
5x. 120m T31 variants
A combined 3 variant approach built using modern modular methods of construction could really begin to reverse the decline and may help to Initiate an increase in hull numbers once again. As I have commented previously, if RN wanted to do something radical this would be a very good place to start.
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