I’m building a floating dock that measures 3' x 10' with a 1' x 6' anchor section.What are my options for attaching them together? Ideally, I would like the least movement possible between sections, but I know there must be freedom for vertical movement between the grounding section and the larger section.—Bill Verhoeven, Delhi, Ont.
Never underestimate the power of water. While floating docks are a good choice because they are less intrusive on shoreline ecosystems, that free-floating characteristic makes them more susceptible to wind, water and boating stresses. Wind, against the large surface area of docked boats, is a powerful sheering force. There are side loads too, sometimes more than intended, from boats docking. All the while, the dock will be twisting and undulating in wave and wake. Build the dock as short as you can manage: longer docks are stressed more and they cost more, needing repair or replacement sooner. Consider width as well, a 3'-wide dock might be a bit tippy.
Good lumber retailers, especially in cottage country, carry dock hardware. There are heavy, welded, galvanized steel hinges with removable pins, inside-corner brackets and chains designed for the job. These types of hinges allow movement so that the base plates are less likely to tear out of the dock frame. Brackets reinforce corners, which are vulnerable to twisting. Bolt the hinges and brackets through the boards, on backing plates with washers. Use galvanized bolts, plates and hinges to prevent electrolysis and rust.
As the dock swings back and forth, it places enormous loads on the shore ramp hinges. The longer the dock, the greater the leverage against the attachment to shore. There are two ways to reduce that stress—at least, partially. At the shoreline, don’t used fixed points of attachment unless you’re sure you can control movement at the outer end of the dock. Instead, consider setting the inner end of the ramp on a plate or flat support, and limit the side-to-side movement with lengths of heavy chain, attached to heavy U-bolts on each side of the ramp and on the fixed plate upon which the ramp will swivel.
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