Big and Small Sisters

The Finnish naval news keeps dropping at a high rate following the contract signing ceremonies two weeks ago. A few further details have emerged on the Pohjanmaa-class, while the FNS Tornio is currently undergoing acceptance tests as the first of the four Hamina-class sisters to pass through their mid-life update.

Screenshot 2019-10-01 at 20.21.54
Still from Saab’s system video, featuring a NH 90 on the helideck. Source: Saab

Saab released a video highlighting the different systems they supply to the Pohjanmaa-class. An interesting detail is the inclusion of a grey-painted NH 90 on the helicopter deck. It nicely illustrates the size of the Finnish Army’s main helicopter relative to the ship, showing that while it can touch down on the deck, it is too large for the hangar and won’t be based aboard. The fact that the helicopter is grey is curious. All Finnish NH 90s are painted in a three-colour green-black camouflage, so either the color is an oversight (likely) or it may portray one of the Swedish Air Force’s maritime Hkp 14F on a visit. This will likely be a somewhat regular occurrence beginning in the last years of the next decade, considering the tight cooperation between the two navies. The Hkp 14F are also the sole non-Russian ASW-capable helicopters of the northern Baltic Sea region, meaning that once they have achieved FOC they will certainly be welcome visitors.

HKP14F
The Hkp 14F showing its whole-grey look and search radar. Source: Lasse Jansson/Försvarsmakten

Speaking of sub-hunting, it had escaped my attention (or memory) that a rather detailed description of the propulsion arrangement had been found in Maanpuolustuksen osto-opas 2/2018. The system will be twin-shafts with controllable-pitch propellers (CPP), powered by combined diesel-electric and gas turbine (CODLAG). Four diesel engines will be working as generators, producing electricity to two electric motors which power the vessel during normal operations. When requiring max speed the gas turbine is fired up, and it will be connected through gearboxes to the two shafts. The total power will be around 30 MW (40,200 hp). An interesting comparison is the German F125-class frigates which sport a very similar CODLAG arrangement rated at 31.6 MW, and consisting of a single LM2500 gas turbine from General Electric (20 MW), four 20V 4000 M53B diesel gensets from MTU Friedrichshafen (totalling 12 MW), two electrical motors (totalling 9 MW), and Renk gearboxes. For those wondering where the rest of the power from the gensets go, there’s quite a bit of electronics aboard a modern warship, as well as a 1 MW bow thruster in the bow of the F125. While no manufacturers have been announced for the Pohjanmaa-class, the F125-suppliers can be considered low-odds candidates. The Rolls-Royce MT30 has scored a few impressive references recently, including replacing the LM2500 on the ROK FFX Batch II, but it might be a tad too big for the Pohjanmaa. For sub-hunting, two of the gensets on the Pohjanmaa will receive additional signature reducing features (acoustic and vibration). This allows slow-speed operations in extreme silence, in essence providing the corvettes with a trolling mode to use a boating analogy (even if the gamefish is on the bigger side in this case). The Pohjanmaa-class is also equipped with twin bow thrusters, a crucial feature to ensure that the vessels can get around unassisted in the narrow waterways of the archipelago, including when mooring at the spartan infrastructure used for dispersed operations.

codlag-diagram
Principal view of a twin-shaft CODLAG system with one gas turbine, twin electrical motors, and four diesel generators. Source: Alureiter via Wikimedia Commons

Commodore Harju, CinC of the Finnish Navy, also published a blog post on the Finnish Defence Forces’ blog discussing the vessels. While giving few details, the blog hints at an endurance of at least two full weeks at sea, quite possibly longer. Considering that the operational environment will rarely sees the vessels being further than half a day of sailing away from the nearest friendly port, this is a significant number and a game-changer compared to the Hamina-class.

Perhaps the most significant message of the post was that the commodore acknowledges the strain currently being placed on the servicemen and -women of the fleet. The service has seen the workload increase with the increased level of readiness that has become a staple of the Finnish Defence Forces post-Crimea. This has hit the small number of vessel crews particularly hard, especially when coupled with the fact that few of the vessels are available during wintertime as well as the prolonged absence of the Rauma-class during their MLU and while dealing with the issues caused by hull cracks following it. This has placed even higher demands on the crews serving aboard the mineships and the Hamina-class FAC. With the change over from the Hämenmaa- and Rauma-classes to the Pohjanmaa-class, crews will have to be trained for the new vessels in parallel with keeping up the operational tempo with ever older vessels. It is most welcome that the Navy leadership already at this early stage of the Pohjanmaa-project acknowledges this, and are making plans to handle this additional requirement.

The Hamina-class MLU this has also seen improvements in this regard. The cabins and berthings of both the sailors and the command have been revamped and moved, allowing for more space. In addition the crews will increase by a few persons, though mostly caused by new functions being added. However, the introduction of newer systems will allow for longer rest periods for the crew members. The ergonomics of the bridge has also been improved. Hopefully these changes will together play their part in lowering the workload aboard the vessels. However, for the Navy as a whole there is unlikely to be any quick fixes, but rather a long and dedicated process is needed to bring the workload down throughout the force. The signs now point to the work having begun, hopefully it will prove successful.

FNS Hanko escorting Kvitbjorn
FNS Hanko (’82’) showing the pre-MLU configuration with the large deck gun and small tower on the rear part of the superstructure. Here the vessel is escorting ro-ro ship Kvitbjørn as part of the buildup to Exercise Arrow 19, a mission that works well close to port and as long as there is no ice. Source: Merivoimat FB

As has been mentioned earlier, the Hamina-class post-MLU will be small but highly competent ships, employing many of the same sub-systems as their larger corvette sisters. The replacement of the large 57 mm deck guns with the smaller 40 mm Bofors in their truncated hexagonal trapezohedron-shaped turrets has freed up weight to allow for the Kongsberg towed arrays to be installed, something that together with the torpedoes (TP 45 for the time being, to be replaced with the NLWT/TP 47 in a few years) gives the vessels serious sub-hunting capabilities. The physical installation of the PTO 2020 (Gabriel) on the other hand proved a bit challenging, with the ceiling having to be raised and new doors being installed. This further underscores exactly how significant an improvement the new missiles has to be, as the RBS 15 Gungnir they beat would have been a drop-in solution when it comes to the physical dimensions. The vessels will get the same combat management system, the 9LV, as the Pohjanmaa-class, allowing for synergies in training and joint operations. The ITO 04 (Umkhonto) in their individual VLS-tubes remain the primary air defence weapon, but the Saab Trackfire has made it onto the rear part of the superstructure. Likely to be fitted with the NSV heavy machine-gun as standard, the remote weapon station allows for better close-range defence against small targets such as small craft, drones, or low and slow aircraft and helicopters compared to the earlier pintle-mounted versions of the same weapon.

Speaking of the Navy’s favorite RWS, the inclusion of two Trackfires on the Pohjanmaa instead of any dedicated hard-kill CIWS raised some eyebrows. The exact capabilities of the Trackfire naturally depend on the sensors and weapon carried, but I decided to place the hypothetical question to Saab: if the RWS carried a suitable weapon and was hooked up to a suitable sensor, would it be able to bring down incoming anti-ship missiles?

In an impressively long answer, the Swedish defence company explained that the system is “designed for very high stabilisation and fire control requirements”. This provide the system with “extremely good performance” when tracking and engaging airborne targets. However, it also notes that the system is set to receive new counter-missiles capabilities in the future, upgrades that will “commensurately increase” the system’s capacity for engaging incoming missiles. In short, Trackfire isn’t yet a mature CIWS-platform against incoming missiles, but the technical possibility is there. Another question is if the Finnish Navy is interested in getting yet another calibre in its arsenal, as the CIWS role would require at least a 20 mm gun, but preferably a 25 or 30 mm one. Something like the 30 mm M230LF could likely be fitted to the Trackfire, but it is questionable if the Finnish Navy would find such an integration project worthwhile. The more likely path is to continue with the NSV, and once the money is available fit a dedicated autocannon (likely as part of a future MLU, which would also include the fitting of a second Mk 41 VLS-module to increase the number of cells to 16).

pieni_PGG TORNIO MLU.JPG
FNS Tornio (’81’) with her new and significantly smaller deck gun. Also note some minor changes to the rear parts of the superstructure. Source: Merivoimat.fi

For the time being, the defence against incoming missiles rests largely on soft-kill systems based on electronic countermeasures and decoy launchers. This isn’t necessarily a purely budgetary decision, as the value of small calibre cannons against incoming missiles at high speeds have been questioned. In essence, if three tons of metal and explosives are hurling towards you at Mach 2, even if you hit it and break something you still have a good chance of getting hit by a lump of scrap metal weighing three tons and bringing a healthy dose of energy (around 706 MJ in our example) into your superstructure. Since that energy transfer is undesirable, having the missile go somewhere else in the first place is preferable.

And what about it being a frigate? To quote commodore Harju’s post:

Some of those who have recently analysed the class have stated that the Pohjanmaa-class corvette is the same size as a frigate and has almost destroyer-like weaponry. A frigate is generally understood as a vessel capable of operating in oceanic conditions […] For us in the Navy, more important than the orthodox definition of the ship class is the military capabilities of the vessels […] And finally, the Pohjanmaa-class is part of our defense system, meaning that evaluating the performance of an individual vessel does not give the whole picture of the vessel, nor the significance and impact of the acquired package.

8 thoughts on “Big and Small Sisters

  1. Perman

    Interesting that Hamina class is getting SAAB Trackfire as well. Would be kind of interesting if an armed Finnish army MD 500D helo could be housed in the hangar and operated from the landing pad with the special forces from Utti Jaeger regiment.

  2. Analysti

    Swedish illustration is not scaled right. FIN MOD puplication can be seen, that HELO-hangar is full size to accomodate at least NH-90 size helos. Of course, rotor and tail folded. Let’s hope that FDF will modify some of NH90’s for maritime use in future.

    1. Yes and no. The Swedish picture has scaled the helo slightly wrong, with the fuselage size on the picture closely matching overall length (with rotors turning). An NH 90 NFH (full maritime version, not to confuse with Hkp 14F) fold up extremely tight, and might be able to squeeze into the hangar. However, that’s not a modification that can be fitted to a TTH, but would be a completely new helicopter buy (also notable that the current number of NH90 in Finnish service does not include excess capability that would allow some helicopters to be permanently rerolled for maritime use). Buying even three NH90 NFH to be able to have one operational would be a 100+ MEur deal, to say nothing about creating a new unit, training crews and maintainers, and so forth. If the Navy suddenly got that kind of a budget boost there’s a number of more serious gaps that could be filled before embarking on a maritime helicopter force.

      1. fpole

        TTH has a folding tail too, see http://www.sbap.be/aircraft/nh90tth2/nh90tth2.htm

        Rotors fold too, but lack the automatic mechanisim of NFH. Of course there are other differences, like strengthened landing gear and “harpoon”.

        Some in the Army would argue that there are more than enough NH90’s in service now, given that its usage has changed from the original requirements.

        But I agree it’s unlikely that there would be a proper maritime helicopter mission for Finnish NH90’s in the future.

  3. Znail

    I think you missed something obvious in the article, the 40mm cannon are quite capable of engaging cruise missiles, so there will be a CIWS. It’s just that the backup to the rear wont be as good.

    1. Perman

      I’m not doubting this, just curious to what exactly makes the 40 mm Mk 4 a CIWS compared to the older 40 mm Mk 2 on Rauma and Katanpää classes. Is it the quick reaction, the accuracy, the sophisticated fire control, the 3P ammo, the amount of ready ammo, the RoF (which is fast but there are other 40 mm gun systems which are faster) or simply a combination of all of this?

  4. Pingback: What about us innocents? – Maritime Defence Day 2019 – Corporal Frisk

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