Wikipedia
The term sportsboat first appeared in the late 1980s and early 1990s to describe high performance trailer yachts with major compromises in accommodation and weight compared to traditional designs of the same size.
They tend to be characterised by historically large sail areas for a given length (especially under downwind sails), light weight construction and a heavy reliance on crew weight to counterbalance heeling forces. They usually feature lifting keels (for easy trailerability) of a modern fin and bulb design and planing hull designs. Most sportsboats are self-righting as opposed to skiffs.
As similar design philosophies spread into larger classes the length of most sportsboats has come to be considered as between 5.5m and 8m (18'-26'). Boats of a similar design but of larger size have come to be known as sports yachts and are generally in the size range of 9m - 12m.