With the current focus on climate change, the shipping industry is forced to decarbonise its fleet. The need for decarbonisation is not only fuelled by the aspirations of the sector but also by laws and regulations from countries and organisations. As these laws are gradually tightening and there is not one clear technical or operational solution, there is a need for a strategy to combine multiple operational and technical solutions. These solutions, as well as other aspects, are associated with risks and uncertainties, such as fuel prices, technical aspects and cost. To help the decision makers in this field, this research aims to present a method that can be used as the basis for a decision making tool. The method will mainly focus on finding the lowest total cost per tonne mile but will also consider other aspects that are found to be necessary, such as safety and technological readiness. The difficulty in the decision is the number of factors that could influence the decarbonisation of the vessel and how these aspects influence each other. The addition of CRSs (Carbon Reduction Systems) will affect the operation profile of the vessel and, with that, the fuel use of the vessel. With fuel being one of the main expenses of ships, fuel use will affect the total cost of the vessel. The method will combine several different analyses to consider all aspects and risks. The strategy will be created by adding CRSs every time the vessel does not comply with the regulations anymore, affecting the vessel's operational profile and fuel use. The cost of fuel use, and other OPEX, will be evaluated with an NPC (Net Present Cost) analysis to compare costs in time. These costs will then be entered into an MCA (Multi Criteria Analysis) and combined with the other criteria, such as safety and technological readiness level, leading to a strategy selection. To increase the method's robustness, the whole set of calculations will also be subjected to a Monte Carlo simulation to mitigate the risks that concern future inputs. The method was translated into a model where a case study was carried out to validate the method and to find some early insights. From this came the result that the method creates valid answers and that there is one method that is the most cost-effective manner to comply with the regulations. This is plainly sailing slower; it has almost no expense and significantly reduces the cost of shipping.