Greenfield Products Rubber Coated River Style Anchor - Black The Tri-Fluke design of the River Anchor allows the flukes to penetrate the river bottom in soft and moderate conditions, or to engage rocks and structure in rivers and current. The River Anchor is a great all purpose anchor for lighter craft, or a great second anchor. Larger models are preferred choice for pontoon boats and other difficult to hold boats. Weight Boat Size Recommended Chain Scope 16 lbs Up to 18 14 x 4 51 20 lbs Up to 2