While regulations may have forced the industry’s hand in terms of developing effective SCR solutions, it was comfort and aesthetics that galvanised the development of Diesel particulate filters (DPF) to eliminate the rather unpleasant soot residue that is deposited as a by-product of combustion.

Now the two have conflated, with the large custom superyacht fleet requiring both SCR, following the introduction of IMO Tier III regulations in 2016, and DPF be complementary.

“The DPF was suitable for removing the black carbon, but it was not suitable for the IMO rules that came into force”, Carlo Bertoglio, Italy General Manager, explains. “There were 50- or 60-metres yachts obliged to follow those rules, asking whether SCR would solve the problem of soot, but it wouldn’t, so they began asking us to add a DPF.”

With IMO Tier III rules well established, demand for an integrated solution is pronounced. “If they have to install an SCR after-treatment anyway,” Lukas Cavegn Product Line Director for marine applications adds, “then they will install both.”


HUG Engineering’s solution is to integrate both systems into the same physical footprint as the generator, with scope for customization depending on the configuration of the space and the various exit piping routes. The integrated solution is certified as Tier III-compliant by DNV GL.

Carlo Bertoglio makes a very important distinction between the HUG Engineering solution and the compliant engine propositions from the OEMs; the latter have not presented a solution for eliminating the Diesel particulate filter. While owners accept their obligation to be compliant, it is invariably the soot that they are more preoccupied with, hence the true value of the combined HUG Engineering proposition. Furthermore, while OEM SCR configurations require DPF to be retrofitted, within the HUG Engineering system, the DPF precedes the SCR, which means the exhaust entering the SCR is already free of soot. This innovation is more compact and reduces the risk of catalytic clipping.

Customers can also switch seamlessly from IMO Tier II compliance (applicable to all yachts cruising the Mediterranean), to IMO Tier III compliance. For the large percentage of the fleet who do the milk run from Europe to the waters of Florida and the Caribbean, this will be a welcome consideration from a performance and efficiency perspective.
“Our historical DPF competence combined with our innovative SCR is having a great success in the <500gt yacht segment across the globe,” Carlo Bertoglio says. “Well-known prestigious Italian shipyards are already excited about our innovative DPF+SCR solution just before the broad global launch.”

By way of example as to the benefits of this system, HUG Engineering has delivered it to a 47m explorer yacht in summer 2020. Both the engines and generators have been filtered, while the main engine configuration has been fitted with an SCR integrated within the filter housing. “Our target is to be the complete solution provider for all yachts’ type.” Carlo Bertoglio explains.

Profile links

Hug Engineering


If you like reading our Editors' premium quality journalism on SuperyachtNews.com, you'll love their amazing and insightful opinions and comments in The Superyacht Report. If you’ve never read it, click here to request a sample copy - it's 'A Report Worth Reading'. If you know how good it is, click here to subscribe - it's 'A Report Worth Paying For'.