It is possible for the vessels to build simple water washing system onboard for the turbocharger turbine sideby themselves. This came up as clogging in the turbineside became a problem - a side effect from slowsteaming worldwide.
You need one piece 1/2" pipe going down to the center of the exhaust pipe before turbocharger, with a closed end (welded, to ensure no loose parts in system before TC). The pipe have to 20 mm past centerline. In the centerline you then drill a 4 mm hole facing towards the turbocharger.
Then you mount a valve on the end of the pipe on the outside that can resist the heat, where you can connect the water hose.
When connecting the water you should apply it with 3-4 bar pressure and then wash for 10-15 minutes at 10 % load !
Normally we open the drain valve to the turbocharger and wash until we have clear water coming through.
It is important to remove the hose after washing to ensure the system is not filling up with water !
If washing at higher load (than max 10 %), this could cause damage to the turbine blades, as the water particles with hit the turbine blades at high impact causing damage!
You can buy a washing system, but pricing wise the crew can build it cheaper onboard with same results,