Kayaking alone in Blessington Lake

According to good practice guidelines kayakers should always be at least three. Things can go wrong so easily and so quickly and a kayaker by themselves can find themselves in major difficulties, whereas if that same kayaker had one or two other people with them the situation can generally be defused before it becomes a major emergency.

That said it comes down to personal proficiency and assuming responsibility. Plenty of kayakers do solo trips; guidelines are really just a suggested guide. Ideally you want to have a very good skill level before taking on any solo kayaking.

He could try joining a kayak club, completing a kayak skills training course or just posting on this forum to find another couple of paddlers...