How can you be 'too buoyant' for an adult lifejacket?

Poor Geoff Holt, the paraplegic sailor who capsized in the Solent at the start of his voyage round Britain, and found himself floating helplessly face down in the water. What a terrifying start to his voyage, and well done to him for carrying on.

But don’t you love the way Geoff was ‘too buoyant’ for his lifejacket? It’s all down to his padded trousers.

That reminds me of the rail disruption a few years back because of ‘the wrong kind of snow’. We should beware of wearing the wrong trousers when sailing. Whatever those might be.