Merlin HC4 - SHOL Increases
 

Ship Helicopter Operating Limits for Merlin HC4 expanded significantly after trials allowing increased payload and endurance.

Extensive trials extend range – or payload – of Royal Marines’ Merlins (mod.uk)

"For nearly a decade, the ‘handbook’ for safe Merlin operations – such as weight limits, wind speeds, humidity, weather conditions – known as Ship Helicopter Operating Limits or SHOL have largely been based on data gathered using the helicopter’s predecessor, the venerable Sea King: older, smaller, lighter."

Errr. WTF - Over?

"Interesting" approach from the MAA & NATG......

I imagine they mean they've been developed by analysis, i.e. in these conditions the Sea King performed like this and the Merlin performs like this so we can safely operate the Merlin within these wind limits. But with much more number crunching. So as long as you've got some SHOL data for a Merlin you can read it across to other ship types based on the Sea King data. It will compromise the SHOL as for safety they won't extrapolate beyond a certain limit so it may be harder to get into limits than it actually needs to be.
To some extent the new SHOLs will also be based on other types performance, as unless they do a trial to each ship class there'll be read across based on whatever type did the most comprehensive trial on that ship, e.g. Wildcat to T45.

From the OP's link I don't think there is anything 'artificial' about the operating weight increase when you load it with ballast!