A person shall not Navigate a vessel whilst under the influence of drink or drugs to such an extent as to be incapable of taking proper control of the vessel
Some may say that is a little ambiguous and I would have to agree with them.
The reason being is that most people when p@@@@d would not have the self-awareness to realise they were not fit for assuming control.
The reality of the situation is that anyone intoxicated on a boat is putting themselves in danger.
Navigating a vessel in any state other than sober is insane and anybody encouraging it is mainstreaming delusion.