We must have been neighbors Jeff... I grew up in Lake Hills (Boeing dad), once we started hearing the hydros starting to qualify during Seafair we'd furiously start making plywood hydros to tow behind our stingrays. Cards in the spokes, etc.
Spent time watching the Green Lake races and Sammamish Slough races too. Best time was Seafair though, from the shore or by boat.
Pic of one of my boats, fastest I have been on water (in a boat).