How early could a fast ocean liner reach 27 knots?

When did 27-knot or faster ocean liners become plausible?

A 27-knot liner is judged plausible in the 1900s or 1910s, although whether one would be built depended on the money its owner would spend on construction and operation.

The comparison starts with Lusitania at 25 knots in 1908 and Mauretania at 26 knots in 1909. Bremen's 27-knot crossing in 1929 is treated as a later achievement that could plausibly have been reached earlier. Spending on the scale of the Lexingtons is suggested as a way to obtain even a sustained 30-knot Atlantic crossing, at a cost beyond what a contemporary company would normally accept. Construction and operating expenditure therefore constrain the proposed speed more than a simple technological cutoff. Cunard's competition between its own fast liners illustrates the commercial value attached to speed.