We have 15 or so 4x4 posts scattered around the lake (50 acres). We rebrush them every couple of years. This past summer I towed 30' cedars out to most of them and tied them off. Green cedars will sink pretty quickly. Bone dry cedar will almost never sink on its own. 30' cedars over 6" at the base are all my boat will tow and those I have to tow backwards. I can take a couple of hours to tow them 1/4 mile.