This one is a spare I picked up from Defender for $25 (overlaid it over the one in the boat and is identical), for the price figured would do something else with the time (tunnels for boy's train set). Note that it is vinyl wrapped thus need to deduct 0.5" from the lengths in the photo to arrive at the dimensions of the wood.
Trapezoid: height 8", bottom 34", top 33", thickness 0.5"
Originally Posted by Sunstreaker
83cm X 20cm X12mm found it on boats.net has pic and part numbers
This seems to suggest the board is rectangular, as per the attached photo it is a trapezoid.