There are some awful youtubers on the broads, claiming big crashes when it's nothing more than someone coming in a bit heavy to moor in strong winds, one of them is one of the worst anglers I have seen on the broads giving 'advice', terrible fish handling skills.
Most of them would rather film a boat sinking than help, I'm not a great fan.
You would need a drawing of your Hull design, 200kg would displace 200 litres of water or 2000 cubic cm, knowing the footprint area of your hull at the waterline you could work it out roughly enough.
If the BA piled and refurbished these moorings with the deal being offered in a few years the landowner refused to re lease everyone would be complaining they wasted toll payers money with a bad deal, no one wants to see moorings go but sometimes you need to look further then just blaming the BA because it's easy.