A leeboard at monohull speeds doesn't make much spray, but at multihull speeds can throw up enough spray to get you wet if you're hiked out above and behind it. While you want a blunt radiused leading edge below the waterline, this is not ideal at the water/air interface.
So I've reshaped the leading edge at the waterline area to a sharp knife edge.
Sailing tests yesterday revealed a vast improvement with the board making no fuss at the leading edge. You can still get splashed going into a steep chop where the water hits the upper part of the board, but the improvement in smoother conditions is well worth the modification.
This will work with rudders too although the spray from it will normally stay aft of the crew.