High Quality Content by WIKIPEDIA articles! H1 Unlimited is an Unlimited Hydroplane racing league that is sanctioned by the American Power Boat Association (APBA), and Union Internationale Motonautique (UIM). Until 2009, the series was known as ABRA Unlimited Hydroplane, in turn renamed from APBA Unlimited Hydroplane in 2004. The H1 Unlimited season typically runs from June through November, consisting of six races.