Hello fellow Vashon owner. There's a post a few years back about the ballast in a Vashon--just search the forums here. It appears they used steel punches soaked in oil. There are pics of the ballast and the owner shoveling it out, which had begun to rust and swell. I've never opened up my keel to take a peek.
Thanks, you are correct, I now know as I too just shoveled out 500 lbs of sodden, rusty steel punching. They were replaced with 100 lb. ingots of lead, along with a new Kubota.