There are folks here who can probably give you an answer on this. However another thought occurs... I don't know whether a timber Tornado would now be competitive within the class, so if you're more interested in creating something a little different and perhaps with a more modern hull shape, I seem to recall that Phill Brander, the designer of the Blade F16, at one point was talking about a 20ft design. He has produced plans for the Blade 16 in timber so perhaps would be interested in doing so for a 20 ft boat, or there is also the Blade F18 design. Phill is a regular here so perhaps he'll chime in.