An important application of the understanding of sea clutter developed in Chapters 2-4 is the prediction of radar detection performance. While many of the phenomena associated with sea clutter are not understood in detail in physical terms, empirically derived statistical models do provide us with the means with which we might calculate detection performance and show how observed clutter characteristics can affect radar performance. This modelling of detection performance is the subject of the current chapter. Here we address the 'end-to-end' problem, which takes as its input radar system parameters and yields estimates of detection probability, but postpone the discussion of the maintenance of a constant false alarm rate (CFAR), and the associated losses, until the next chapter. The confirmation that real radar systems do in fact perform in a manner consistent with these calculations is presented in Chapter 10; thus this and the following two chapters now justify, in a practical context, much of the analysis presented in the rest of the book.