There was quite a few incidents where ships go in fact faster in combat compared even to top trial speed.Did not mean to offend you mate, 25.8 on trails was the top speed that was over a measured mile, the load would be optimal and the stokers fresh. One thing people tend to forget in this era is coal fired ships were dependant on the stamina of the stokers. These high speeds you hear about like the Lion doing 28 knts at Dogger could only be maintained for a limited period
Put a strain on a machinery - of cause, but it was possible if ship was in good condition.
If you really want to live you can really break records..