DOC / DPF / Catalyst Options for Diesel Mains & Gensets

I am replacing the dry exhausts on my twin mirrored pair of Gardner 6L3B's on my 1965 G. De Vries Lentsch Jr built TSDMY. As part of this I am exploring the possibility of including a catalyst or some kind of particulate filter (DPF) into the new arrangement which also includes restoration of the funnel and mast back to its original 1965 incarnation (as per the pic). The engines will thus exhaust at a reasonably low air-draft height through a funnel which sits atop the original boat deck (as per the pic). The boat deck these days is used much more for general entertainment and therefore I seek to keep it as free as possible from smoke, particulates and noxious gases. Obviously I understand that back pressures can't be compromised. I'm most interested in whether anyone has done this before and if so, what was your approach? Please no-one try and talk me into a wet exhaust conversion. With regards to the Gensets they are a pair of new Cummins Onan MDKR17.5KVA Quietline Series again being directed dry up the stack and on to the boat deck. So X4 chimneys in all.

I guess this is an area that not two many people are keen on venturing discussion on. Having said that, I've just looked at the discussion threads in these forums on both the D'Angelo Seaclean system and the one where a reader was speculating on the application of AdBlue systems which exist in trucks and cars. Both those discussions are now having me err on the side of dispensing altogether with the idea of a DPF / catalyst system. With a long range motoryacht such as mine there likely to be long periods during passage-making where the Gardner engines will be running at 40-60% of full load on low RPM's. Similarly, even though I have deliberately bought 17KVA gensets to "up the average loading" of the gennies (and I can even split the bus between the two gennies), there will be many periods where they sit at 30 - 40% of load. Both of these conditions are ripe for the clogging of DPF's and catalysts it would seem. Interestingly Toyota here in Australia is now facing class action from its fitting of DPF's to all Hilux and Landcruiser Prado SUV's since 2014. Owners have been complaining about loss of engine power and massive loss of fuel economy. There seem to be reports of the same in the commercial trucking market in the US and Europe where many workshops are now offering services for the removal of DPF systems which have been installed on big rig diesel trucks. Seems this area is a veritable can of worms that I'm going to steer clear off. The only option I might still loot at is the option of a flanged "can" filter that can go at the very end of the exhaust pipe. If I keep all the gennies and main engines with minimal elbows on the run through the stack and use only "straight through" absorption type silencers this might be be the way to go as they will be easily removed in a position outside the funnel on the boat deck . The idea being that you could simply unbolt them and clean them out manually.

For those interested in this topic I found Marmot's comments in this thread to be most instructive https://www.yachtforums.com/threads...logy-be-installed-in-boats.27262/#post-240936

Thanks for all your comments. Please also forgive my spelling / grammar in my reply to my own post above. I was typing on my phone and was not checking! All your comments are very useful. I approached De Angelo through their agent in Australia hoping they had a small Seaclean system. The response was negative at this stage. I agree Capt Ralph that inverters are the way to go and I like to have a quiet ship on the inverter but sometimes with families aboard and everything that comes with that the genset has to come on! The more I have looked the more I have seen the internet is rife with engine repairs and even failures from diesel motor cars with DPF's / DOC's fitted....things seem to go terribly wrong when these diesel vehicles are used for daily short commutes where the engine never gets hot enough or runs long enough to regenerate the soot. In studying this topic I think I've now figured out why my wife's Mercedes GL SUV recently went in for a $6000 service to fix engine oil leaks even though it was only 3.5 years old. I bet there was a clogged DPF to blame as she only does short runs to school and shops etc... Then motoryachtlover has confirmed the same in trucks. The diesel engine community is in a real mess with this stuff!

For now I'm going to keep both gennies and mains in a straight a run as possible up the stack with straight-through absorption type silencers to minimise back-pressure. I'll then explore a simple "clip-on" style scrubber which someone mentioned in another forum. The clip-on unit is apparently is "the size of a coffee can" and clamps on the end of the exhaust pipe. The purifier is easily removed (and I assume cleaned) when it is no longer needed. https://www.foleyengines.com/products/exhaust-purifiers-scrubbers/diesel-exhaust-scrubbers/ Sounds to good to be true but at least this way I've not got something trapped in the middle of my exhaust between two flanges out in the middle of nowhere!...and in long range passages i can just remove the thing. Seems that back pressure exhaust monitoring is a good idea when playing around with these things. Any idea how to set up a monitoring point in the exhaust arrangement top check back-pressure?

Trickiest one of all is when it lights out and its too hot and sticky to NOT have the aircon on! Even X4 Cruiseair units go down to quite a low load when they are all working to just maintaining the airtemperature through the night. But I guess that's when you really don't care whats happening up top on the bat deck because no-one's up there then! The trick would then be to load it up with services first think in the morning and clear the exhaust lungs then

Thanks. The canoe stern definitely has a positive impact in a following sea. She is a 1965 “Deep Ocean Class” long range motoryacht built by G. De Vries Lentsch Jr in Amsterdam. The build was commissioned by a New Zealand industrialist who sailed her round the world direct from the yard when the build was done. G. De Vries Lentsch Jr was the “by Royal Appointment Yard” who built the yachts for the Dutch Royal Family. Starting in 1840 it was the oil crisis of the early 1970’s that eventually saw their demise after building nearly 3000 custom craft. I am only the fourth owner of MY Sirdar and I have undertaken a total refit from the keel bar up. I hope to launch within a few months but will take longer if I need to in order to achieve exacting quality on every aspect.