The 'displacement tail' ...can you elaborate ?

The tail has always been designed to sink under pressure, that's why it has such low area and soft rails. The low lift tail moves the fulcrum forward and allows excellent pitch control and balance.

Garrett with displacement tailed craft

The planshape is a cross section of a foil section, my idea back in 1997 was that the tail could then operate efficiently whether on top of the water or submerged.

We also make similar tails with flatter rocker and tunnel fins. In that case the tail doesn't sink due to the lift from the tunnel but is still a 'displacement tail' in that it has the typical pintail which most efficient non planing craft use. Of course the board still gains most of its lift from planing, but could be described as a planing/displacement hybrid. It certainly uses a higher proportion of displacement lift and has a closer resemblance to displacement hulls than the so called 'displacement hulls' by Liddle and others.

If one looks closely at the videos of the Dragon board which I've posted recently water can be seen wrapping over the tail and the tail can be seen sinking and rising as speed, wave shape and rider input change. It's a 'self tending' feature.

Thanks to Garrett McNamara http://www.garrettmcnamara.com/  and Sean Davey    www.seandavey.com