Why a 170-gun first rate would strain its world

What problems would a 170-gun four-deck first rate face beyond steering?

Its size would require a new generation of dry docks and supporting facilities, making infrastructure as limiting as the ship itself.

The hypothetical 170-gun Kent has a longer, deeper hull intended to avoid the problems of enlarging an existing ship. Even if that solves the proposed handling difficulties, the ship still has to fit its shore facilities. Its size would require a new generation of dry docks at the places expected to support it. The brief answer makes dock capacity an additional cost of the larger design.