We are going to examine Hull Speed from three different perspectives.

• Speed Length vs Displacement Length
• Displacement Length Speed
• Displacement Length Ratio.

It is a very worthwhile exercise to compare S/L (Speed Length) Ratio as calculated from, Displacement Length, from Max Displacement and SHP, and from “true” S/L based on LWL.

All three calculation will give different answers to Speed Length Ratio, which is to be expected, but it is important that all three answers are of approximately the same magnitude. If they are not, particularly where one answer is quite different from the other two, this is a valuable indication either of an error in data input or specification itself.