When it comes to acquiring, specifying or designing a good, we're usually faced with a choice between several products on the market, or between several solutions likely to meet an expressed need. To decide which of the competing options to choose, we need to evaluate them, in other words, be able to compare their value. This involves, on the one hand, the overall cost of owning the product, and on the other, the level of satisfaction of the need, which includes, in particular, operating safety characteristics.
The information needed to define these characteristics must be identified, then estimated qualitatively and, if possible, quantitatively. The approach adopted takes into account reliability, maintainability, logistical support and, in some cases, the vulnerability of investments. These various concepts, and more particularly that of maintainability, are described here, followed by questionnaires designed to assess them. The example of marine energy conversion systems, for which the choice of an industrially viable technology is particularly challenging, and which involve a wide range of competing solutions, will sometimes be used to illustrate the approach.