Swimming in the Marina.. in Boat Talk Posted July 14, 2020 3 minutes ago, Randall Harbert said: What do you clamp the spring clamp to? The negative jump start post or something metallic like the cleat? Just wondering...probably never use it but would like to know..thanks for sharing! Neg side of your battery. But this does not stop some one from getting hurt or killed. It just protects your boat.