Boat stand blocks are square cut rectangular pine blocks used to safely and securely support boat keels. These blocks hold the entire weight of any boat stored on land before shoring up with boat stands.
Brownell recommends using a minimum of two blocking piles placed on hard stable ground. Piles should consist of two larger blocks running fore and aft parallel to each other with a third smaller block on top, spanning across for the keel to rest on. More piles can be used for longer boats and piles can be stacked higher in areas to accommodate different shaped keels.
Best practice is to keep boat blocked as low as possible for stabilility.