UK Defence Forum

Great news from "our foreign correspondent", thx!

Can someone remind me of how the B2s are better than this B1.5 singleton?
- I remember the more warship-like construction std, and enlarged/ more numerous mag's for weapons (including one for use on the helo deck)... not much more (there must be?)

Brasil wrote:Brazilian Navy to receive patrol vessel HMS Clyde in 2019

Good news!

Depending on the future fishery requirement, Clyde might be needed in UK. But if not, Brazil is a good place. Although this is not for export (just a lease), it shows a good future "possibility".

- River B1.5 has good commonality with Amazonas (and River B2). Although its outlooks differs a lot, the two designs' cross section is very similar (while the main engine differs). = might be easier for Brazil to use it.
- Brazil is a good export customer for UK for long. Good relation is very important.
- If Clyde is "good", when in future UK are to replace or reduce 3 River B1s, it will be a good export candidate.

ArmChairCivvy wrote:Can someone remind me of how the B2s are better than this B1.5 singleton?
- I remember the more warship-like construction std, and enlarged/more numerous mag's for weapons (including one for use on the helo deck)... not much more (there must be?)

River B2 has CMS, Clyde does not. (This is big difference)
River B2 top speed is 25knots, Clyde is 20knots.
River B2 has an optical FCS on the mast, Clyde does not. (Am I correct?)
River B2 has an EMF accommodation space for 50 soldiers (below flight deck), Clyde does not.
(But, Clyde does carry 50 or even more soldiers in short-period transport tasks in Falklands Islands).
River B2 can carry 2 20ft ISO containers not on flight-deck (up to 6 including flight deck), Clyde I have no info.

An impressive list. The CMS on early Rivers you can count as a 'training facility':
"CS-1 is inherently scalable, over 25 consoles are being fitted in Type 45, a single console variant has been delivered to the Royal Navy's Offshore Patrol Vessel (Helicopter) program and a five console variant will be fitted to RFA Argus"
from BAE in 2007 (, as there was only one OPV prgrm at the time)

Not really news but surely now a containerised CAMM/SPEAR3 system should be developed. Could be fitted to all RFA and minor vessels as needed if CMS2 is standard as it seems.

At 3:55 the reservist states the RNR will be manning the OPVs, which means the the personnel from e.g. HMS Calliope will be manning them by the sounds of it, like we did with the Ton Class until the 90s. They only require a crew of 35 anyway so not much of a strain on manpower, of course there is the support and maintenance team as well, I assume they'll return to Portsmouth for anything serious! Fantastic news for the RNR and it shows how innovative Gavin is being by utilising all the assets at his disposal.
Im sure it'll only be part time, working at the weekends, or when there is a need for more, similar operation to the Ton Squadrons in the past!

Excellent video. Thanks for sharing.

KDW579

Only the 10th MCM Squadron was manned by the RNR. All the other "TON" MCM squadrons were RN manned.

P-121 APA
River class

HMS Mersey in drydock in early November....


And now....

HMS Medway (P223) has passed initial sea trials.
https://www.royalnavy.mod.uk/news-and-l ... sea-trials

Saw this on SNAFU today. This might be the way forward for the Rivers especially if we keep the B1/2 groups. They could be used as forward support especially of you upgrade the 30mm mount to the SIGMA Seahawk. Add in a NEMO or CAMM/Spear 3 Container and you have something not all that far off the Black Swan idea from 2010.

Is it reasonable to place a big slow vessel that close to a hostile coast when a patrol boat has a very limited self defenced capability?

I do like the NEMO system, it could be a great candidate for a modular weapon fit to fast landing craft. I'd suggest its better to adapt the Rivers to support some fast combat boats, rather than sending an OPV directly into battle.

shark bait wrote:Is it reasonable to place a big slow vessel that close to a hostile coast when a patrol boat has a very limited self defenced capability?

I do like the NEMO system, it could be a great candidate for a modular weapon fit to fast landing craft

I agree, but would rather drop the NEMO container on a deep-skirt hovercraft (fairly immune to mines, as trialled by the USN for clearing them):
Type: Hovercraft
Displacement: 84 tons
Length: 27.4 m (90 ft)
Beam: 15.4 m (51 ft)
Draught: -
Installed power: 2 × Vericor TF40 gas turbines (6,000 kW)
Propulsion: Two air propellers
Speed: 50 knots (93 km/h; 58 mph)
Complement: 10
Sensors and
processing systems:

EADS ANCS 2000 combat data system
SAGEM EOMS
- on the sides there would be room left to have e.g. the 23 mm Mauser (with its insane rate of fire) for self-defence... would deal with attack helos, too, with ease
- 84 t displacement would surely accommodate tons of mortar bombs... that the NEMO can also eat "at speed"

So: at 50 knots, 7 mortar bombs a minute (continuous rate) to shore - out to 10 km, and 1700 rounds per minute pouring out from either/ both side(s) should any pesky attack boats/ helos appear... and did I mention it yet : who cares if that stretch of coast has been mined

Is she due to follow Mersey in to dry dock for a much needed repaint?

Here's a little boxing day discussion topic.

In a discussion elsewhere some one suggested adding a sonar module that could be operated from the deck of the some of the River Class. The motivation was to create a cheaper alternative for local patrols, allowing the shrinking escort fleet to focus on the carrier group. What do people here think?

If the Rivers had a quiet-running mode, I would say that it might be worth a trial. But, as far as I am aware, they don't. Does that make a huge difference in the sort of littoral ASW that I think we are envisaging, though? Would a decent HMS and an offboard towed array be more successful?

Caribbean wrote:an offboard towed array be more successful?

3 t in all and specifically for shallow (noisy) waters:
"weighing under 3 tonnes and can be rapidly deployed for high speed manoeuvring in addition to full stop (dipping mode). The unique ST2400 VDS is a compact package with Omni-directional coverage and performance that can overcome challenging acoustic environments while not limiting the vessels manoeuvrability.

Kongsberg Maritime Subsea Naval, Director of Sales, Thomas Hostvedt Dahle said: “The Finnish Navy has been our key partner from the early development of the first ST240 VDS in the 90’s to the latest version of the ST2400 VDS that we have today. It has been field tested in challenging conditions in the very shallow parts of the Baltics where reverberation issues and layers are dominant. We look forward to continue to improve and develop our system to operate in probably the world’s toughest ASW environment"

ArmChairCivvy wrote:3 t in all and specifically for shallow (noisy) waters:
"weighing under 3 tonnes and can be rapidly deployed for high speed manoeuvring in addition to full stop (dipping mode). The unique ST2400 VDS is a compact package with Omni-directional coverage and performance that can overcome challenging acoustic environments while not limiting the vessels manoeuvrability.

Kongsberg Maritime Subsea Naval, Director of Sales, Thomas Hostvedt Dahle said: “The Finnish Navy has been our key partner from the early development of the first ST240 VDS in the 90’s to the latest version of the ST2400 VDS that we have today. It has been field tested in challenging conditions in the very shallow parts of the Baltics where reverberation issues and layers are dominant. We look forward to continue to improve and develop our system to operate in probably the world’s toughest ASW environment"

Hmm - that sounds like it might be worth a try, at least

I would like to see some testing of littoral ASW done from the Rivers if for no other reason than to see what would be needed from the new MHPCs to take on this task

That was my thoughts, it could be a useful experiment to help inform the decision making on the future MCM program. Easy to see a large electrically driven utility platform towing a sonar around Scotland.

In the mean time the new River's are big platforms, and supposedly have good sea keeping ability, so perhaps they could help release a little pressure on the escort fleet.



The French trialed a towed sonar off the back of their landing craft, so fitting one to the stern deck of our patrol boats it technically feasible. A River OPV would have to go slow to limit the effects of self noise, which is probably ok for patrolling territorial waters.

shark bait wrote:A River OPV would have to go slow to limit the effects of self noise

The vessel on the left is fitted with the said Norgie sonar, and the one on the right will get it (in place of the RIB shown on the photo) https://www.km.kongsberg.com/ks/web/nok ... penElement
- the point though is that signal processing for eliminating self-noise must be pretty good
- as both types shown are driven by waterjets (awfully noisy; even when gurgling in a slow gear?)
However RR has had access to this all electric demonstrator https://www.globalsecurity.org/military ... -081-s.jpg to try out a new type of water jet (all electric, minimising the internal noise and the waterjet itself designed to clearly beat propeller cavitation noise levels) where also flow noises, around the hull have been minimised: https://www.globalsecurity.org/military ... 6w-052.jpg

All you need to do is to put a suitable lifting arm in place, to get a working deck: https://www.globalsecurity.org/jhtml/jf ... 6w-103.jpg|||

... and because of the moderate size of the vessel, when there is a contact, task a land-based asset (or simply a Wildcat from a frigate) to deliver the torp ... the ASW kit on Merlins doubles their unit price (and we don't have enough of them anyway)
- so a tired term, a" force multiplier" might come to apply here

Compact VDS/TASS examples:

As the ship noise is not strong above ~1 kHz, while those VDS/TASS in active mode is using ~2 kHz (CAPTAS-1) or 22-29 kHz (ST2400), maybe "River B2 noisy" issue will not be a big problem.

Thales CAPTAS-1 (<2 kHz)
With Blue Watcher (hull-mounted FLASH), it is specifically designed for adding ASW capability to OPV-class ships.
From this brochure, we can see it can be carried on 10-ft container (3 m long, 2.5 m wide, 2.5m high), with another 10-ft container for signal processing. https://www.thalesgroup.com/sites/defau ... ptas-1.pdf

ATLAS ACTAS (?? Hz)
From ATLAS electronic. Containerized version exists. This is also proposed for ARCIMS USV drones. https://www.atlas-elektronik.com/filead ... _ACTAS.pdf

Kongsberg ST2400 VDS (22-29 kHz)
Shallow water VDS, widely used in Baltic sea. https://www.km.kongsberg.com/ks/web/nok ... ion_lr.pdf

Reference: Accoustic noise at sea

Ultimate the systems now exist to deploy these kind of systems (mcm/asw/surveillance) on usv’s primarily directly from shore especially from around the uk overwatch could even be provided by a protector uav. You don’t need a river, though it could meet up with one and take on fuel to extend endurance. If more sophisticated asw is required then we assign an asw frigate, as this is our primary defence requirement the descretionary tasks of mid and Far East come second.

SW1 wrote: If more sophisticated asw is required then we assign an asw frigate

Or we make them to work as hubs and usv's would then work around them as spokes... greatly increasing the area(s) that can be covered as frigate sized ships will always be at a premium
- now, for that greater area (one frigate, one helicopter - so not always immediately available) the Japanese version of ASROC might hold some appeal (with its extended range and supersonic flight)