Long-distance maritime transport provides 80-90% of global trade, but strict regulations around NOx, SOx and greenhouse gas (GHG) emissions are set to cause major technological shifts. Whilst the pathway to achieve the International Maritime Organisation (IMO) target of 50% GHG reduction by 2050 is unclear, what is clear is the need to drastically reduce the industry’s dependence on fossil fuels. Liquified natural gas (LNG) is reaching mainstream and provides 20-30% CO2 reduction and other alternative fuels such as ammonia, hydrogen or biofuels could decarbonise much further but face significant barriers concerning financials, resource potential and acceptability. In tandem, considerable fuel and GHG savings could be attained by implementing efficiency measures such as slow steaming, improved ship design and utilising renewable resources. With wind being a truly maritime feature, the onboard harnessing of wind energy will play an important role in the decarbonization of the long-distance maritime transport industry. However, its uptake has been slow and there are significant challenges to its widespread adoption in the commercial shipping sector. WHISPER will develop a novel modular retrofit solution comprising a wind-solar hybrid power system to significantly reduce auxiliary engine emissions and a tilting wing sail system to provide wind-assisted propulsion significantly reducing main engine fuel consumption and emissions. Wind power will be harnessed through novel containerised turbines which will be demonstrated on an in-service container ship with efficiency savings of 15.3%. WHISPER will prove the technical and financial viability of the complete retrofit solution on in-service bulk carrier vessel, demonstrating efficiency savings of 29.8%.