The Half Ton Class was created by the Offshore Racing Council for boats within the racing band not exceeding 22'-0". The ORC decided that the rule should "....permit the development of seaworthy offshore racing yachts...The Council will endeavour to protect the majority of the existing IOR fleet from rapid obsolescence caused by ....developments which produce increased performance without corresponding changes in ratings..."

When first introduced the IOR rule was perfectly adequate for rating boats in existence at that time. However yacht designers naturally examined the rule to seize upon any advantage they could find, the most noticeable of which has been a reduction in displacement and a return to fractional rigs.

After 1993, when the IOR Mk.III rule reached it termination due to lack of people building new boats, the rule was replaced by the CHS (Channel) Handicap system which in turn developed into the IRC system now used.

The IRC handicap system operates by a secret formula which tries to develop boats which are 'Cruising type' of relatively heavy boats with good internal accommodation. It tends to penalise boats with excessive stability or excessive sail area.

Competitions

The most significant events for the Half Ton Class has been the annual Half Ton Cup which was sailed under the IOR rules until 1993. More recently this has been replaced with the Half Ton Classics Cup. The venue of the event moved from continent to continent with over-representation on French or British ports. In later years the event is held biennially. Initially, it was proposed to hold events in Ireland, Britain and France by rotation. However, it was the Belgians who took the ball and ran with it. The Class is now managed from Belgium.