When lengthening the O3 hull would be practical

How difficult would it be to lengthen the O3 hull and add a third shaft and machinery for more speed?

It would be comparatively easy during the design phase, but more complicated and expensive after the ship had been built, though not impossible.

A viewer asks how difficult it would be to lengthen the O3 hull and add a third shaft and machinery for more speed. The change would not be especially difficult if made before construction during the design phase. Altering an already built ship would be more complicated and expensive, although still possible. A paper design allows far more freedom than the structural and financial burden of reconstructing an existing hull.