I live on a lake that's 7.5ft deep with about 18 inches of silt below that. Our lake has ski boats, wakeboard boats and surf boats. The ski boats never churn up the silt on the bottom, but many of the surf boats leave a chocolate milk trail behind them from churning up the silt. On the other lakes in the neighborhood that are 6ft deep, all of the surf boats churn up the silt.