Building Your Own Dock. Sam Merriam

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      Since our structure is in an aquatic environment which happens to be corrosive, let’s consider alloys and coatings for a moment. The usual shiny plain steel, electro-galvanized fasteners you find at the hardware store will begin to rust in a short time, especially around salt water. For the time it takes to build your project, it is worth spending extra money for better corrosion resistance so you’re not re-doing it in a few years. Around fresh water, electro-galvanized screws with a resin coating, offered in a choice of colors, perform well on decking and framing. Buying coated screws can be a “pig in a poke,” not knowing the quality of the coating. To qualify what you’re buying, begin with the specifications offered on the product’s label. It should boldly say that it is suitable for marine environments, otherwise, keep shopping. If your project will be exposed to salt water, make sure the product states specifically that it has been tested for salt water. If you can correspond with the company, ask how rigorous their testing is. An adequate test by my standards would be a continuous six month to a year period. If rapid corrosion will occur in a salt environment, they would see early stages of it within that time. Also make sure that the manufacturer recommends their product for the type of chemically treated lumber you may be using.

      The alternative to resin-coated screws would be hot-dip galvanized nails or stainless nails and screws. To reduce damage by electrolysis in salt water, I would go with grade 316 stainless if your budget will allow it. I realize that it could be cost prohibitive, especially when you look at upgrading bolts to stainless. In that case, for salt water, I would attach zinc bars, as used on marine outdrives, under the dock frame to retard corrosion on hot-dip galvanized fasteners. In fresh water, hot-dip galvanized fasteners perform excellent above the waterline. Below the waterline, from my experience, the galvanization will be gone in a few years. Once the galvanizing is gone, the plain steel in fresh water could hold out for many years but there is no telling exactly how long. For anything that you’re building that will be underwater, lean toward stainless.

      If you plan to use a nailing gun, you’ll likely speed up the assembly time significantly. I recommend using a 3-inch (7.62-centimeter) hot- dip box nail that is ring-shanked or with a spiral. Be sure to blunt the tips to prevent splitting at the end of a board.

      If nailing red cedar or redwood, you can expect the galvanized nail heads to turn brown from an interaction between the zinc fastener and tanning oils in the wood. It never bothered me but it might bother some people.

      Though the nails hold very well, one complaint I hear about is the nail heads creeping up over time. This is more of a problem with floating docks than fixed. Wood floating docks can torque or twist from end to end as waves roll through, a little or a lot, depending on how well they were made. Prolonged torquing can cause nails to work up through their holes. The shrink and swell cycle of the boards may also contribute to this. Either you cope with the problem, appreciating the other attributes to nails, or use screws instead. Just be aware that if torquing is the culprit, it will work on the screws too. They either creep out like a nail will or fatigue and snap at the heads. You should use a heavy-enough wire, like a #10, and work on reducing the torque in the dock.

      As a framing fastener, structural screws install very nicely with a variable-speed cordless impact wrench. These are available by several manufacturers in various lengths, coatings, and head types. If you haven’t used these before, don’t be surprised at how easily an 8-inch (20.32-centimeter) screw will install. As with any fastener, make sure that the manufacturer rates the product you’re looking at for the treated wood you’re using and your environment.

      When considering your choice of head types available, whether for decking or framing, Phillips drives work well when going into cedar. If you’re going into a harder material, such as treated wood, either use a square or star drive. Structural screws are available in a hex drive that I’ve never stripped out, but I prefer the heads that are round or flat with a star drive as they are more hull friendly if brushed by a boat. If you experience trouble with the bits breaking, try a higher quality brand made with a harder steel. On deck screws, fluted tips are worth getting to reduce the chance of splitting the end of a board. If using conventional tips, pre-drill the ends of all deck boards since decking should be cut flush with the frame on a dock.

      For mounting specialty dock hardware, joining posts with a frame, or cap boards, I recommend through bolting. Do not rely on lag bolts where through bolts can be used.

      If possible, use all carriage bolts, keeping the heads to the exposed surfaces as they are hull- and skin-friendly while the hex nuts will be turned in. If the hex nut and the threaded end of a bolt must be on a surface that could be exposed to a hull or skin, countersink an area so that the nut and bolt set within.

       Dock hardware should be through-bolted.

      Around fresh water you should use hot-dip galvanized screws. In salt environments, I prefer stainless if it’s in the budget. I have a word of caution when using stainless bolts and nuts. They have a strong propensity to “gall” or seize together. Sometimes they seize before the nut is tight against the surface you’re fastening to. Once this happens, applying torque to the wrench will likely snap the bolt. Before putting stainless bolts and nuts together, inspect the threads for grit or imperfections. Then hand-tighten before applying torque with a hand wrench. Tightening at a slow speed prevents heat that can cause galling. An alternative to this would be to use brass or aluminum nuts on stainless bolts.

      When drilling for bolts, match the hole size with the bolt diameter. Sometimes a slightly bigger hole is preferred so that the bolt fits into the hole with ease. That may be okay, but if it is on a component that will experience motion, such as a hinge for a floating dock, I recommend keeping a tight fit. Locking nuts, such as a nyloc, would be great if you could find them for galvanized bolts. Otherwise, locking washers are the “go to” but I recommend liquid thread lock and or double nutting. They add another level of protection to secure parts that experience motion, vibration, and wear. RTV silicone applied to the threads will also dampen vibration and help prevent bolts and nuts from working apart. Upon tightening bolts to wood, be sure to include flat washers where a hex head bolt or nut tightens directly against a wood surface.

       Countersunk holes help to reduce contact with an abrasive bolt.

      If you’re planning to use eye-bolts for hinging dock sections or holding significant loads, be sure to use load-rated, shouldered, forged eye-bolts. Eye- bolts that have been formed into shape with a rod may not do the job. Make sure you know its capacity and that it is fit for the job you’re subjecting it to.

      Pipe leg dock hardware, made for СКАЧАТЬ