Tiki 38 'Pilgrim' was built by a group of Frenchmen near New York and sailed from there across the Atlantic to the South of France in July 2011. They made the crossing in record time, 4500Nm in 31 days. This means they averaged 6 knots, including the stops in Azores and Portugal! They frequently sailed at 14 knots and their top speed was 16.6 knots.
The Tiki 38 has a WL length of 32ft, i.e. √WLL = 5.66. Therefor 16.6 knots = 2.8 x √WLL, 14 knots = 2.5 x √WLL. These speed/length ratios compare very favourably to those achieved by highly expensive ocean racing multihulls and this for a self-built low-cost cruising boat with a low-tech Schooner Wharram Wingsail rig.
Do watch the wonderful film they made of their voyage and read their blog: