Meko A200 - CODAG WARPA Propulsion (look Ma no funnels!)

**Monash** · 17 May 12,, 10:33

I came accross an article about the above propulsion system which is being fitted to an upgade of Blohm + Voss's well known class of frigates. Apart from thinking "what a great idea why has no one tried that before" I do have a couple of questions that I thought the experienced hands here might be able to answer.

Firstly am I right in thinking that all the power plant's exhaust gases are "vented" under the water line (via the jets?).

Secondly if the above is correct how much more "stealthy" is this approach likely to make the vessel. I can see it's thermal profile being changed significantly and getting rid of the "stack" reduces it's silouette but would the benefits outweigh the costs?

Lastly I recalled reading some time ago about some marine engineers experimenting with reducing hull drag on commercial cargo vessels by trying to vent gasses along the bow line to reduce drag. The idea was to try and obtain significant fuel savings. Are they doing this here or could they and would it be worth while.

Cheers

**kato** · 17 May 12,, 12:59

Originally Posted by Monash

Firstly am I right in thinking that all the power plant's exhaust gases are "vented" under the water line (via the jets?).

It vents below the stern bulwark, after injecting the exhaust gases with seawater. As usual for such a design the exhaust port is above the waterline, the engineering difficulties of keeping the water out would be too complicated otherwise.

Diagram:
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What's revolutionary about it is the use of water jet propulsion in a ship that size, not that much venting exhausts at the water line. The latter has been done by corvettes of German and Russian design for decades, although stern venting usually tends to be more of a Russian design feature - German corvettes tend to vent at the sides of the ship, mostly because the area behind the engines is used otherwise; with WARP the exhaust manifold is simply installed above the water jet taking up the area towards the stern of the engines anyway.

Stern of A200; the "fish mouth" is the water jet, above it is the exhaust vent:
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**Monash** · 17 May 12,, 13:15

Thanks heaps for the technical info kato. Do you work in the industry?

**kato** · 17 May 12,, 13:19

Example for similar stern venting ports in a Russian Tarantul: [here] (the covers close when not used; the stern ports are only used for the M70 turbines, diesels or M75 turbines vent through the funnel).

Side venting ports in a German K130: [here].

In the K130, they "discovered" that the exhaust damages the paint (gee, who would have thought). Hence why the corrosion-protection black paint is drawn higher behind the exhaust ports.

And no, i don't work in the industry.

**Monash** · 17 May 12,, 13:32

Does the side venting on the K130 complicate docking/laying up alongside other vessels? Plus I noted the layout of the secondary/point defence systems on the two vessels. The fore and aft layout of the Sea Ram mounts on the K130 seemed quite straitforward, but the rear mounted side by side (point?) guns on the Tarantul seems a little "odd" or is there another mount forward - I coudn't tell from the angle in the picture.

**kato** · 17 May 12,, 13:45

No, not really. The exhaust is cooled with seawater to a manageable level (which of course is primarily done for signature reduction), also automatically making the gasses denser so they stay at the water line. Offhand this is also the case for German MCM vessels, also 20 of which also use side ports. Running on diesels at low speed you barely have any visible exhaust.

It's not without problems though. Couple years ago apparently one of the manifolds in one of the K130s "leaked", resulting in the lower decks being filled with exhaust gases. And Soviet Parchims, not using water injection, always have had the problem that in certain weathers and at speed the exhaust billows upwards from the side ports and converges directly on the top deck at the stern.

**Stitch** · 17 May 12,, 20:30

What are the advantages to having a hybrid propulsion system like this? Why not JUST the pump-jet or JUST the diesels? And am I right in assuming they use the same fuel (thereby obviating the need for carrying two types of fuel) since the turbine is capable of burning diesel?

**kato** · 17 May 12,, 21:39

Umm... CODAG is pretty standard, and has been in use since the 50s.

Combined diesel and gas - Wikipedia, the free encyclopedia

**surfgun** · 18 May 12,, 00:26

So the diesels turn the screws and the turbine turns the impeller.
Are the diesels running when the turbine is running? or are the propellers being dragged through water when the turbine/jet pump are in operation?
When the diesels only are running is water still running through the jet drive tunnel (causing drag)? or is there some sort of intake cover?