What a charmingly odd word. The Guardian tells us that

Yngling is, quite simply, a type of boat (…) invented in 1967 by Norwegian Jan Lingel, who wanted to build a boat for his son, Oyvin, who was 14 days old at the time. The word means youngster, with the boat named in honour of the teensy Oyvin.

Nothing to do with the oldest known Scandinavian dynasty.
Although the Guardian refutes accusations that it is a sport invented by the British to win more medals, the Daily Mash confirms my suspicions:

Stewards lose track of yachting classes. "I’m pretty sure the British invented at least two of them on Saturday afternoon," says official.

In case you’re interested, the French Federation of Sailing gives drawings of all the different boats.