Design global warships for the South Atlantic first

If one body of water had to define a ship intended for worldwide service, which should it be?

Use the rough South Atlantic as the seakeeping baseline, then add air conditioning for hot-weather operations.

The South Atlantic provides a demanding baseline for hull form and seakeeping. A ship that can operate there should cope with calmer waters elsewhere, while air conditioning can adapt it to tropical service. Hull form determines fundamental seakeeping, while climate-control equipment can be added.