Project 03160 ‘Raptor’ Capable of 48 kts?

Swedish blogger/twitterer Observationsplatsen yesterday posted a video published by Pella JSC of a Project 03160 ‘Raptor’ (ru. Раптор) performing trial runs. The trim of the boat during runs is rather more positive than in the case of its Swedish counterpart, something that spurred me to do some number crunching.

The nose-high running of the Raptor. Source: Pella JSC
Strb 90
The flat running profile of the CB 90. Source: Wikimedia Commons & Norwegian Defence Forces.

As said, what seemed evident from the video was that the boat traveled in a nose-high position, which generally means that the center of gravity is too far aft and/or that the boat has trouble getting through the transient phase and into the planing phase. The original CB 90 does not, meaning that something apparently went wrong for Pella. As said in my original post on the Raptor, reverse-engineering is not as easy as it seems.

A disclaimer to begin with: it is possible that Pella is simply performing their test-drives at half-power. However, I lack any idea of why they would choose to do that, and post a video of it without any notice about the restrictions imposed.

The hull form of the CB 90 is not optimized for planing, being of the semi-displacing kind. This provides better sea-keeping abilities, but it also means that there is less horizontal surface to provide the dynamic lift needed for planing. On the CB 90, this is accentuated by the very narrow chines. According to the three-view plans provided by Dockstavarvet and Pella JSC respectively, the width of the chines doesn’t seem to differ in any remarkable way. The difference in performance must thus come from something else.

The narrow chine of the CB 90. Source: Author.
The narrow chine of the CB 90. Source: Author.

According to Dockstavarvet, the CB 90 has a displacement of 18 tons, being powered by two 805 hp engines, giving a thrust to weight ratio of 89 hp/ton. The Raptor is cited by Pella as 23 tons, with two 1133 hp engines (curiously enough, the English version gives the total power as only 2 x 1000 hp). This gives the Raptor a higher thrust to weight ratio of 98 hp/ton, a 10% increase compared to the CB 90. However, this performance increase comes at a price. The original Scania DSI 14 engines of the CB 90 had a dryweight of around 1700 kg apiece. Pella has not given out their engine of choice on their homepage, but a secondary source of uncertain value gives the engines as Caterpillar C18’s. This seems logical, as several of Pella’s tugs have been fitted with Caterpillar diesels. The C18 has a dryweight of 1950 kg, or 400 kg more weight for the pair of marine diesels. Another change is in the type of waterjets employed. The Rolls-Royce FF410 of the CB 90 had a dryweight of 485 kg, and an entrained water volume of 192 liters/kg. I have not found the model or manufacturer of the waterjets of the Raptor stated anywhere. However, if one looks closely at the drawings provided by Pella, it becomes very clear.

Water jets
The stern with the water jets of the Raptor. Source: Pella JSC.

That, my dear friends, is a Rolls-Royce Kamewa A3-series water jet, most probably of the 40A3-model. Unlike the axial-flow FF-series, the A3 provides a hybrid-flow design, giving higher performance. However, another major difference is in the material. Where the FF-series is made of aluminium, the A3 is of an all-steel construction. This raises the dryweight to 850 kg apiece, with an entrained water volume of 186 litres/kg. In total, a simplified calculation of the weight of the drive package (not counting liquids, turbocharger, transmission, shaftes, …) of the Raptor gives a total weight of 5970 kg, with the corresponding value of the CB 90 being 4755 kg. This is a 25% increase in the mass of the drive train (compared to a total increase in displacement of 28%). In fact, the increase in weight of the engine and water jet accounts for roughly 24% of the total increase in displacement.

The important part, however, is the fact that the drive train is placed at the stern of the boat. This gives any increase in weight in the drive train a large impact due to the long lever. As the increase in weight of the jet and engine is in line with (in fact slightly under) the general increase in weight of the boat, this should not affect the trim of the boat if all added mass was distributed evenly.

Why then does the Raptor travel around with its nose in the air? I have no definite answer. It is possible that the added ballistic protection or an increase in engine room insulation has caused a shift in the centre of gravity aft. Another possibility is that the lengthening of the hull (the LoA of the Raptor at 16,9 m is two meter longer than the 14,9 m of the CB 90) has caused a similar shift. The fuel tank is also probably situated slightly aft of the centre of gravity, meaning that an empty vessel with full tank(s) would be trimmed more nose-high than a loaded vessel with empty tanks. The hard numbers available indicates that the boat should be able to attain the 48 knots specified. However, until Pella releases a new video, I will stand by my opinion that the Raptor does look more like a 35+ kts boat than a 48 kts.

Project 03160 “Raptor”

The Pella Shipyard of St Petersburg, mainly known for their tug boats, last week officially launched the first series produced vessel of their new Project 03160 ‘Raptor’-class (ru. “Раптор”). This boat is rather interesting, if not for anything else, then at least because it bears a striking resemblance to a 30 year old Swedish design…

Project 03160 “Raptor”. Picture from Pella Shipyard.

The internet seems to differ whether the boat is in fact a licensed version of Dockstavarvets Combat Boat 90/Stridsbåt 90, or if it just “happens” to look like one. However, what is certain is that Dockstavarvet sold a number of its Interceptor Craft 16 M, a patrol craft based on the CB 90 concept, to the Russian border guards (FSB)[1]. The Raptor, however, seems to be based on the original CB 90 instead of the IC 16 M, and it is clearly stated that this time the customer is the Russian Navy, with at least four boats slated for the Black Sea Fleet.

The armament is rather interesting, with a single remote weapons station with EO-sights and a single 14,5 mm heavy machine-gun. The “Range of target detection – 3000 m” is a value which naturally doesn’t tell us anything, as there is no mention of what kind of target and environment this corresponds to. The back-up weapons are two pintle-mounted PKP light machine guns, which is a somewhat strange choice. The PKP, or 6P41 “Pecheneg”, is a development of the PKM, and mainly differs from this in having a non-replaceable air-cooled barrel, and an integrated bipod, and as such is marketed as a dedicated squad-support weapon.

Whether the Raptor mounts the baseline version, and actually retains the bipod, or not remains to be seen, but this could be an indication that the Russian marine infantry is about to ditch the PKM completely in a relatively near future (another alternative, naturally, is that the PKP is simply listed by the yard as a marketing trick, but that in service the boats are fitted with the PK-derivative that is closest at hand when sailing). All in all, a quite solid, but not overly heavy weapons fit, which should provide ample opportunity to “intercept and arrest […] small targets”. The inclusion of ballistic protection, at the expense of weight, and thereby speed and agility, adds to the feeling that the Russians expect the boat to operate on the battlefield where small arms fire (both own and incoming) can have an effect on target. This could well be not only close to the shore, but also in riverine conditions.

The role of the boat seems to be accurately described on the home page. Key focus is on transporting an assault force, with a secondary  anti-shipping/anti-surface capability (or as a patrol vessel in peacetime).

Looking at the camo scheme, it does feel more suitable to the inland waterways of south and central Europe than to the coastlines of the Baltic Sea, but this might just be my prejudices about how a “proper” boat pattern should look if it is to fit in in the Gulf of Finland.

Is the boat then a copy of the CB 90. If it is unlicensed, I believe the answer is ‘No’. The general layout certainly seems copied, but it is hardly revolutionary. Pella might have borrowed more than is considered “fair”, but the general characteristics of the CB 90 is conventional enough. To try and reverse engineer the details of the CB 90 would probably not have been worth the hustle. To begin with, Pella would have to send a number of engineers to a boat and measure it up, down to what size the bottom stringers are and how high the masthead light is, as well as document every little detail of the equipment. After this, the engineers would have to create the whole drawing package from scratch, after which they would have to adopt it to Pella’s materials and standards. What is the size of the Swedish chairs? Does Pella’s standard choice fit? What can be used instead? How is the Russian ballistic protection attached, compared to the original?

The other possibility is naturally that Dockstavarvet indeed have licensed the production, but understandably wants to keep a low profile about it. See edit

Simply using a proven general layout, and starting an own design from there, is far faster than “true” reverse engineering. And I think speed is the issue here. Projecting boats from the keel up is a long process, even when it is a relatively small and straightforward one as the Raptor. Going through all the normal stages, with a preliminary round of tenders, choosing a winner, nailing down the details of the design, producing and testing a prototype, building a pre-production run, and then finally going into series production, usually takes at least a few years. Here it seems like the first steps have been skipped, and the project jumped straight into the detailed design phase. The result is a stop-gap vessel, built to expand on current capabilities (and numbers), rather than revolutionize them. This also fits the general trend of rapid expansion of the Russian armed forces.

Edit 22:45 (GMT +2 DST) 25062014:

When the pictures first surfaced last spring, Dockstavarvet’s CEO K-A Sundin strongly denied any involvement, and stated that Pella apparently on their own have gotten their hands on “some material” and created a clone.