The analysis of submarine control design under the framework of individual channel design (ICD) is presented. The boat considered corresponds to the 80 metres standard British submarine. It is shown that under the ICD framework the multivariable control design of submarines can be solved, in an effective and clear manner, by applying classical techniques based on the Bode and Nyquist plots. It is also shown, in a constructive manner, that the analysis in this context leads to the most simple designs possible, which in this case are diagonal controllers. The characteristics of the solution to the control problem is determined by the multivariable structure function resulted from the definition of the input-output channels. By analysing the multivariable structure function it is shown that diagonal controllers can be used effectively for both sets of channel definitions. Comparison with previous designs obtained by applying the polynomial-H/sup /spl infin// techniques highlights the effectiveness of the ICD framework.