Being an unballasted dinghy, Spark's centreboard serves two purposes. The obvious one is that it allows the boat to sail "into the wind" without skidding across the water with no control. The second is that it is a nice bit of leverage for flipping my GP back upright after the inevitable knockdown. These two factors require that the board on Spark be as strong as can be practically possible. Bell woodworking did this by making it of solid mahogany.
As Spark had been used as a racing boat for most of her time afloat, use had not been kind to that large chunk of mahogany that pivoted down from her keel. The "handle" had been cracked and repaired at least once and there were several large dents worn into the trailing edge from where it had beem "slammed home" during racing when every second counts. All in all, the centreboard had lived a hard life.