Note that a simple one line description and key assumptions are given in the decision tool itself as a quick reference, these can be seen by clicking on a efficiency method. This page gives more detailed information on how the efficiency methods have been modelled in the Whole Ship Model.

The efficiency methods in the Whole Ship Model are modelled in Python. They provide both cost and performance information to the ship and are scaled with many different input parameters, including ship speed, ship size and type and engine loading. For example, a simple steam waste heat recovery model may not be work effectively at lower engine loads when there is less energy in the exhaust. This can be written into the file describing the waste heat recovery efficiency method so that when the performance of the ship can be calculated effectively for a range of operating conditions. Secondary impacts, such as the impact on propeller and engine performance, are also calculated in the Whole Ship Model.

This reference of an old model explains the technology/efficiency method interface in more detail and how a way of approximating the performance of multiple efficiency methods:
https://doi.org/10.1016/j.oceaneng.2014.12.014

Appendix 2 of a recent report done for the Danish Shipowners Association by U-MAS gives more detailed information on the assumptions for the efficiency methods. This includes feedback from the Danish Shipowners and Lloyds Register.

See the Report for the Danish Shipowners Association

Since the Danish Shipowners Association study propeller polishing was added to the list of technologies and some technologies were improved.