The SAAF Forum

This might sound as a bit of a stupid question: The Strikecraft has four main engines. When cruising at see do they use all four engines or do they switch off two and run on the other two. They must be very heavy on diesel. Just wondering...

You could conceivably run it on any combination of engines from 1 to 4. However we never, in my time, ever used anything less than 4 unless we had a malfunction. Fuel use is a function of horsepower. Something like an average of 230 grams per hour per horsepower or around 3/4 teacup of diesel. The strikecraft, like the crashboat, cruised at 1300 rpm at 22 knots - for best speed/fuel consumption. On a strikecraft this meant around 4000 horsepower (of 16000+) being used. Or around 850 litres per hour. (All the above varies with sea and air temperature and tonnage - which is constantly getting lighter as fuel is consumed).

In later versions of this engine MTU adopted sequential turbocharging with electronic injection which ran only a certain numbers of cylinders at optimal load - opening the valves on those not firing and not injecting fuel into them - and achieved better fuel usage by doing so at the expense of more complicated engines. The engine functioned, in effect, like a modular engine with pairs of cylinders being brought into operation as demand increased.

Old marine diesel engines had the ability to "hang" a piston. This meant that if a cylinder malfunctioned the piston could be disconnected from the crankshaft and secured in the cylinder by means of captive bolts in the cylinder head. This of course gave rise to a generation of chief engineers in pubs trying to outdo each other with tall stories of just how many pistons were left working as they nursed their ships home.

As an anecdote - we were once giving rides to the general public on a crashboat when some old grizzled Mooreesburg farmer, thinking of his tractor no doubt, buttonholed my old man with a "Seun, hoeveel myl per gelling kry julle". My father's reply of "Oom, ons gebruik so 4 gelling per myl" rather rattled the old omie.

Gripen1: I like the old adage..."There's no such thing as a stupid question" because that creates knowledge sharing.

Thanks for the comprehensive reply Eugene.

Thanks Eugene
What are the Stikecraft main engines? V16 or V12? A friend of mines late father (Snyman?) was a mechanic on the Tafelberg. I was told they carried a massive spare piston on board for "just in case". I also heard of them blanking off a faulty cylinder on a marine diesel. That Stikecraft sure is a thirsty beast!

The strikecraft were/are fitted with the MTU 538 V16 TB92 diesel engines of a nominal horsepower of 250 metric horsepower per cylinder. The "538" stands for 5.38 litres per cylinder. The crashboats had the MTU 538 V12 TB90 engines of a nominal horsepower of 175 metric horsepower per cylinder. In the fifteen years that elapsed between the 2 engine models the major improvements had been cast steel, rather than cast iron cylinder heads. And advancing and retarding l'Orange injectors - plus the more powerful turbochargers (denoted by the TB92 in the designation). But essentially the same engine. Maybach Mercedes (later incorporated into MTU) manufactured this engine in everything from a straight 4 to a V20 engine with only very few components being different. I think it was their brag that only 62 components varied in the entire range. As train engines they regularly achieved a million kilometres between major overhauls. But as train engines they had a top speed of 1200 rpm - whereas the naval versions had 1800 rpm on the crashboats while the strikecraft top rpm was 1920. Eventually, in the 1980s MTU pushed this same engine with sequential turbocharging to 500 HP per cylinder at 2240 rpm. If you were ever in the engineroom of a strikecraft or crashboat at night at high speed and someone switched off the lights you will no doubt remember the eerie spectacle of the exhaust stubs glowing cherry red. Of course the time these engines could run at flat out speeds was limited - so many minutes in every so many hours. Every high speed run over maximum sustainable power chewed up engine life! My old man limited the crashboats to 1670 rpm - except in "extreme emergencies". Any time the revs were exceeded it was a "please explain and justify" situation!

Big slow cathedral diesel engines such as fitted to large mercantile ships of Tafelberg's era had huge pistons - the engine stood three to six stories high - and ran at speeds up to 130 rpm - but most were around 85 to 100. They were invariably 2 stroke engines. Burmeister Wain on Tafelberg.
Usually a complete spare unit was carried - piston. cylinder head, injector, liner etc. and these underwent maintenance at sea. As soon as harbour was gained one unit would be overhauled with the replacement parts. Easier than on a high speed small diesel! Everything done with special power tools and overhead gantry crane. On the MAN Kz85 three engineers (usually the 2nd, 3rd and 4th) would do the operation in a morning. 8 am start - lunchtime finish. In this way the engine was in effect constantly being renewed with every eight voyages seeing the entire engine overhauled.



A Sulzer piston and connecting rod, crosshead assembly. The 8 cylinder engine from which this comes weighs 593 tonnes.

Just to clarify a point I made earlier about fuel consumption. I perhaps spoke as if this was a fixed thing. Not so. One thing in physics is that if you can say "It varies" with great conviction you have it made So with fuel consumption. Which is usually depicted in a graph of fiendish complexity designed to create awe in the non-initiated and baffle the hell out of engineers who have to pretend to understand them. They take into account several variables that may have a bearing on just how much fuel the beast is drinking. Here is one for an MTU-538-V16-TB92 engine:



If you could have gotten Picasso to sign it it would fetch a squillion at Sotheby's. Wait till you see the graphs of hull loading .....

Not really - it's actually quite fuel efficient at cruising speeds. Almost twice as fuel efficient as the Type 12 frigates were. At flat out speeds, 29-30 knots, a type 12 would consume 11 tons of fuel an hour. 3 tons per hour at 18 knots.

A couple of years ago a friend on mine was based at FMU (i think?), or the boat graveyard. He was an electrician and had to check up on the boats at the graveyard. Anyway, he showed me around the Strikecraft. I noticed the Strikecraft had a forward and aft engine room, each with two MTU V16 main engines. Each engine room had what looked like a engine room watchkeeper cubicle with all the engine guages, switches etc. Do they have a person in each control cubicle for each engine room whilst out at see? How do they control the main engines? From the bridge with a message to the engine room oke, or directly from the bridge.

Eugene?

The forward and aft engine rooms are usually manned by a watchkeeper each - they do not control the engines except in emergency local control mode when 2 watchkeepers are required in each engine room. I per engine. The watchkeepers maintain a continuous watch on all sorts of things, do hourly rounds logging gauge readings and so forth. Between the two engine rooms you have a ECR - engine control room. Herein sits a senior engine room person. Usually either the engineer officer, the chief or the second. They monitor the computer readouts and gauges and so forth. The engines are normally controlled from the control desk in the wheelhouse - the throttle control being transferred from the ECR to the Wheelhouse after everything is running OK in the engine rooms. In normal conditions they are operated by seamen and only in elevated readiness states does one of the senior engine room watchkeepers take the throttles in the wheelhouse. Entering and leaving harbour, for instance. In elevated readiness states the engine rooms are manned by two watchkeepers and the ECR usually has the engineer officer and the chief in it while the second takes the throttles in the wheelhouse. Although the engine room complement of a strike craft it 9 it can, in emergency, be run with fewer - we once took a strikecraft to sea with only the engineer officer, myself and a CF watchkeeper. But no relief possible without endangering the integrity of the machinery. Each engine room not only has the two main engines but also two 6-cylinder generators, switchboards, fire pumps, fuel pumps, HP air compressors (230 bar), air conditioning equipment, fresh water generators and other odds and sods - not least of which is the kettle which supplies coffee to the senior in the ECR. With the noise in the engine room most conversation is carried out using a complicated set off handsignals and flashing lights. The most important of which is a "C" made with the left hand using the thumb and forefinger. This means "Make Coffee".



This is a view of the ECR on P1562 with Lieutenant van Schalkwyk (Chalky) on watch. His right hand is on the throttle for engine no 2 - the starboard engine in the aft engine room. Just under his
left sleeve can be seen the lever which transfers throttle control to the wheelhouse. Each main engine has a panel, as seen. The red button Chalky is pressing is giving computer printouts for the individual cylinder heads on engine no 3. The printers are above the windows in the ECR. There are further panels for the generators and a ship control panel which gives warning of flooding and fire in each of the twelve compartments plus other interesting information.

Thanks Eugene for that interesting insight.

I never knew that engine room watchkeeping on a Stikecraft is so involved. It must be a very hot and noisy place to be. I once went down to the Drakensberg's engine room whilst at see on a family day and it was incredibly noisy. I also remember the Crashboat turbo's whining whilst giving stick. I know this from work where I often work in the boiler house on our JTA steam boilers. Not nice on a hot day.

Does the Stikecraft share lineage to the German Type 143A Gepard class missile boat? It has a slightly smaller displacement but looks very similar.

Designed, largely, by the same people.

If you are on Facebook then go to:

http://www.facebook.com/media/set/?set=a.354670294624605.83287.100002449117212&type=3

for a sample of some of the many FAC/MTBs that Lürssen werft has designed over the years for many countries. They were the premier Western designer and supplier of these craft for the latter half of
the 20th century.

If you can't get to facebook I've made s alideshow here:

Thanks Eugene

Friederich Lürssen pioneered and developed the semi-planing hull in the first fast military motor boats of the early 1900s and by 1916 was delivering motor torpedo boats to the German navy. During the interwar period the yard built many fast pleasure craft - especially for the American market and it was a 1924 motor yacht built for an American which formed the basis of the famous S-boats (which the ill-informed call E-boats). The S-boat hull shape's hydrodynamics were so well established that the design still influences many fast attack craft. While many only think of Lürssen as a fast boat pioneer - they also built the first Voith-Schneider driven minesweepers in 1932 and were the lead yard for the R-boote of WW2. Whereas yards in countries outside of the German sphere of influence concentrated on planing hulls - Vospers and British Power Boat being two of them - that particular hull form starts taking a knocking from rough waters far sooner than the semi-planing hull.

Our strike craft are basically the Lürssen FPB 57 hull. The "57" denoting 57 metres in nominal length.
This hull form has served, since the 1970s, in more than 300 FAC built in many yards around the world. Originally Lürssen was to have built the Israeli SAAR4 class based on this hull - and indeed took a lead in the internal design - but it turned out that Israel Shipyards could give a cheaper quote and the Israeli government was happier that the things got built locally in case of arms boycotts. The famous French Cherbourg missile boats (SAAR1, SAAR2 and SAAR3 classes) were Lürssen vessels - the FPB-45 hull. Germany had a complicated trade agreement with France which involved the French in building the Type 148 at CM de Normandie in Cherbourg for the German Navy.as part of the deal. Which is why the identical Israeli SAARs were built there too. Lürssen itself at the time did not in any case have spare capacity as it was involved in too much work for the German and other navies to take on the job. Even at Israel shipyards the entire engine room and propulsion train was the responsibility of German companies which delivered that section of the ship.

In modern weapons manufacture, especially as it relates to ships, there is no longer much chance of a "single source" shipyard as in days of yore. So many pieces come from so many countries it almost makes going to war impossible. I once penned this for someone:

Warrior class strike craft - a truly international vessel:

The entire engine room and drive train was supplied by, fitted by and guaranteed by MTU of Friedrichshafen. All items in both enginerooms - main engines, gearboxes, generators, AC achinery, fresh water generators, fire pumps, venturi units, fuel pumps, compressors were made in Germany as were the propellers, propeller shafts, P-brackets, rudders, exhausts, changeover flaps, etc. The only major non-German items were the two main electrical switchboards which were made in France.
The static and dynamic inverters were however German. The steering gear was Swedish, located in the tiller flat. So was the active cathodic protection - located on the hull and in the aft heads.

The forward and aft gunbay equipment was likewise Oto-Melara of Italy. In the CIC the intertial platform and vertical gyro was supplied by Plath and Anshutz of Germany. The main plotting table was by a Dutch firm, whose name momentarily escapes me. The radios were mainly French (Elmer) and German as were the Antenna (Rhode & Schwartz). Some of the internal comms nets were USA (Rockwell) as was the emergency lighting equipment.

The EW suite was Israeli as was the Dagon Radar - which was an Israeli development (with French assistance) of the Thomson-CSF Neptune. The Orion 10 gunnery radar was Italian as was the Officine Galileo optical director. The WAMO was partly Israeli partly Italian and the Missile Control Unit was Israeli. Of course the entire Gabriel missile and it's systems were originally a South African design - but in the mid sixties the SA Navy showed no interest so the developer took the whole shooting match to Israel (which had experience of being on the wrong end of Komar and Osa missile boats) where development cash was forthcoming. Even the lavatories were French! So largely only the hull was really Israeli made and that with Iscor steel plates! The explosive bonded strip
connecting the steel hull to the aluminium superstructure was USA though!

Thanks for that interesting insight. I get the feeling a lot of modern military equipment today have the Germans to thank.

Edit: I never knew the Gabriel had it's origins in South Africa?

Edit: What is this: "explosive bonded strip
connecting the steel hull to the aluminium superstructure"