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Water Jet Fast Attack Craft review

5th Dec 2012 11:28 pm

To celebrate Navy week, we bring you an exclusive test of the Water Jet Fast Attack Craft.


  • Make : INS
  • Model : Cankarso

The INS Cankarso. If you have never heard of it, you must be one of the good guys. If you happen to be a pirate ship operating off the coast of India or Africa, it’s a name you will never forget. This very ship we're on engaged and sank a pirate ship off the coast of Lakshwadeep in January 2011. The INS Cankarso is no ordinary navy ship. Designed to take on a very specific role, it is a boat engineered to meet a very contrasting set of demands. Built specially for the navy by Garden Reach Shipbuilders and Engineers (GRSE) in Kolkata to fight piracy, terrorism and all manner of shallow-water threats, this boat is fast, manoeuvrable, well armed and has the ability sail in water no more than three metres deep. Like all patrol craft, the Cankarso has also been designed to have massive endurance and range; which makes attaining all the other objectives pretty difficult. And there lies the engineering challenge. 

Bow to stern (or front to rear to us land-lubbers), the Cankarso is purpose-built. The first few compartments in the bow consist of the boatswain’s storage, the ammunition room, the pump room (that houses bilge pumps in case the ship is taking on water), a desalination plant and a reverse osmosis plant that can convert sea water into drinking water. That’s if the ship’s 10,000-litre fresh water tank runs dry.

Behind this is the crew’s quarters and the two engine rooms – the forward engine room for the port and starboard engines and the aft engine room for the centre engine. This configuration is important to keep the boat well balanced. Even in ships, it is important to get as close to the 50:50 front-rear weight distribution as possible.

The rearmost compartment, as you can guess, houses the three massive Hamilton water jets. Every one of the ship’s compartments is watertight, and that means if a part of the hull gets holed under attack, you can seal that particular room off and the ship will stay afloat.

There are three levels of watertightness as well. You have the basic ‘X’ level for all rooms below  deck, ‘Y’ for all compartments on deck (used in medium-rough seas) and ‘Z’ where the superstructure is secured (used when Poseidon is in a foul mood).

The Cankaro’s bridge has one captain’s chair, but it is very unlike the ones found on an Innova. Set high, so the captain has a good overview of all that he oversees, it also gives him a top view of where the ship is going. 

His ‘dashboard’ from left to right consists of a radar screen, steering, compass and a moving, GPS-like map with additional info like depth and the position of nearby ships. Controls for the engine and water jets sit to the right of these, and further right are the remote controls for that 30mm cannon.

There’s plenty of headroom and legroom too; in fact, the INS Cankarso has accommodation for four officers and 45 sailors. The officers’ quarters are in the superstructure while the sailors are all housed below deck. Navy ships ◊ ∆ are designed to have flexible accommodation and it is the same here – if there are fewer sailors on board, bunks can be removed easily to improve space in the living quarters.

By warship standards, equipment levels are pretty good – the Cankarso is centrally air-conditioned with two air-con plants that keep the crew cool, there’s Tata Sky to keep the crew entertained and informed, and build quality is as tough as a battleship.

You can’t opt for airbags or a sunroof, however, and basic safety gear like seatbelts are missing on the bridge. 

To fully understand what the Cankarso is all about, you need a few kilometres of open sea, a strong stomach and a firm hand on the throttles. Push them wide open and, along with a discharge of more froth than a beer factory from the rear, the nose of the boat slowly inches up. The deep rumble of the diesel engines turn harder edged, you can feel the sea rushing past much faster, and as harbour gives way to open sea, the jet-propelled boat starts riding the crests of the big swells like a giant sea monster.

Down in the engine room the noise is deafening; like Thor, god of thunder, is screaming in pain after stubbing his toe. The turbos whine in anger like a tempest gone mad, 48 massive cylinders, each displacing four litres, continue to churn, and still the Cankarso gathers pace. 

Acceleration, as you can imagine, is pretty gradual. The seas were really rough the day we were on board, so we only hit a max speed of 53kph, with the Cankarso taking approximately 400 seconds to get there. Sure, the grey Ferraris are unlikely to hold a candle to the red ones, but the pace is nevertheless very impressive.

But while Ferrari may prefer V12s, the Cankarso uses a team of three V16 diesels. If the sea was calm, we could have pushed the boat all the way up to its 35-knot top speed.  Don’t think that’s fast? Try and imagine your apartment building going past you at 65kph and the momentum it would be carrying. Manufactured in Ranchi under license from MTU of Germany (a company owned by Daimler and founded by Wilhelm Maybach), each of these 16V 4000 M90 common-rail diesels puts out 3650bhp, the power sent to the water jets at the rear by individual driveshafts. The 4000 in the name stands for the cubic capacity – of each cylinder. Each engine has two sequential turbochargers and, add up the power, and you get a total of 11,000bhp; quite a serious amount, you’ll agree.

Other auto industry references include a single-speed ZF gearbox, cylinder deactivation that turns the V16s into V8s to save fuel, and a single, all-encompassing ECU. The biggest difference between these engines and the ones used in cars is that these use sea water for cooling, so there are no radiators and no large fans either.

Final transmission of power is handled by the three Hamilton HM811 water jets. Driveshafts connected to a centrifugal pump draw water in through an intake at the bottom of the hull. Water under pressure is then forced back through a nozzle and this is what provides thrust. With the use of a reversing bucket (the official name is ‘split-duct astern deflector’), reverse thrust can also be achieved. It’s clever, it isn’t too complicated and, most importantly, it needs less maintenance than a regular propeller-rudder combination.

The Cankarso is also 30 percent more agile than a regular propeller-and-rudder ship. Water jets are much more flexible and the stream can be pointed in pretty much any direction with the help of the ‘buckets’. Similar to thrust-vectoring on some military aircraft, the water jets can even provide sideways thrust, so the ship can literally turn 360 degrees where it’s standing. And the Cankarso also stops much better than regular ships – the buckets simply direct the high speed jets under the ship towards the front. On a conventional propeller ship, maximum braking is achieved by first stopping the propellers, and then reversing them, and this usually takes a lot longer. Remember the Titanic?

So the Cankarso can turn and stop on a dime, but it still rolls like a ship. As for the ride, you can compare it to an SUV pummelling its way over rough terrain. All you have to do is stay on the power and hang on. Ultimately, it’s not a luxury liner, so the ride not a priority. 

Built to have a deadly combination of speed, range and agility, the INS Cankarso and her ilk are also known as the ‘Grey Ferraris of the Sea’. Like a Ferrari, this ship is all about low drag, low weight and careful weight distribution. Actually quite large for the role it plays, this 48m long and 7.5m wide boat is positively gigantic when compared to the machines we normally test. But though it may be as large and as unwieldy as a block of flats, the hull is pretty slippery. It has a drag coefficient of 0.45 and this slippery shape helps the INS Cankarso and her siblings achieve their top speed of 35 knots (65kph), and that’s pretty quick on water.

Part of its sheer speed also comes from the pared-down weight. To save kilos, the hull is made of different thicknesses of steel and the superstructure above is made of aluminium! Sounds like Audi was involved here. “We managed to shave around 20 tonnes,” said Bhattacharya of GRSE, which left all of us gasping. So ‘kerb’ weight is down to a featherweight 325 tonnes, which is like a saloon weighing less than a hatchback.  

“Chassis stiffness also plays a big role here,” the engineer said, to which we all nodded knowingly. There are 42 transverse braces (U-shaped ribs that hold the hull’s steel plates together), and the spine has special reinforcements, which means the Cankarso can operate with full effectiveness at up to Sea State 4 (waves the height of buses) and can survive Sea State 5.

What makes water-jet-powered boats different, however, is that, unlike conventional ships, there are no protruding rudders or screws at the rear. Water jets handle both propulsion and steering, and that allows the ship to operate in very shallow water. In fact, since the Cankarso needs water just 3m deep for it to operate, it could theoretically sail right into your local swimming pool if a Jolly Roger is spotted.

This isn’t a battleship, so armament is light. There’s the aforementioned 30mm automatic cannon with an electronic day-and-night fire control system and armour-piercing rounds, two 12.7mm heavy machine guns and multiple light machine guns. The vessel also has its own boarding party to counter a pirate attack. 

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