alt="images"/>
A family cooperates to survey offshore for the desired length and depth of their dream dock.
So often, the path, bank, or seawall leading to the dock is at a different elevation from where the dock is to be set. Therefore, I prefer to use my first section as a ramp from the shore that spans across and slants toward my second section. In this scenario, the first section will get no legs at all since pitching it would cause them to be off plumb. The two legs that were assigned to the first section get bumped over to the second section. The second section can free-stand now on four legs like a table and is bridged to shore with the first section.
If you use the standard sections shown in this book, they are typically 10 feet (3050 millimeters) in length. Using the first section for a ramp, determine the length needed to slant safely, while spanning between the desired resting point on the shore and the second section. Though I like to stick with 10-foot (3050-millimeter) long standard sections as often as possible, you may need to make them longer if starting from a high elevation. The shore end of the second section is where your first set of legs will stand. Flag the spot where the ramp rests on the shore while making note of the length it needs to be.
Check for fluctuating water levels: I would first establish what the stability of the water level is like. If the dock gets only seasonal use, concern yourself mainly with what the fluctuation is doing during the months it will be in use. Look for a fluctuation not to exceed a range of about 2 feet (6 decimeters). Fluctuations greater than this would better suited for a fixed dock that can be adjusted during the season or maybe a floating dock. Facts about the water level are often revealed close by, just by observing other docks in the area. If there are other fixed docks, make note of the distance they are set off the water. Seeing more fixed docks than floating is an indication that the water level is stable. You’ll also notice water stains, like a dirty ring in a bathtub, upon rocks, boulders, and seawalls along the shore.
Determine where the first set of legs should stand.
If there are no references like that to observe, check for a debris line further up the bank away from the water’s edge. You’ll see where the high water pushed twigs, rogue weeds, and other litter. Ask a neighbor or two who has experience with the body of water about how great and how frequent the level deviates from the mean level. It would be helpful to know typically month by month what the level does and if you should be aware of any sizable event such as a “twenty-year flood.” If there isn’t a neighbor to supply this information, then a local marina operator should know. If your body of water has a dam, the ones commissioned with its management can tell you.
Predicting exposure to waves and current: Boat chop and large waves driven by prolonged winds can damage a fixed dock if the dock isn’t set at the proper height. The surface area under the decking is enough for a large wave to push against from below and lift the dock, dislodging the legs from the lake bed or seabed. While at the site, I look at the reach to the farthest shore opposite from me. If it is close to 1 mile (1.61 kilometers) or more, the chop from the wind could become severe. The longer the reach, the larger the waves could get. Find out what the maximum wave height could reach. Once you know, plan on setting the dock so that large waves will pass underneath, clearing the underside. For example, if the highest wave measures vertically no more than 3 feet (915 millimeters) from crest to trough, the dock will need to set no less than 1 ½ feet (460 millimeters) off the water when it is flat and calm.
The first dock section may stand off the shore while another section is used as a ramp to bridge the gap.
Fixed docks should be set at a height so that the largest waves present will not pound and lift the dock from its position.
If your shoreline happens to be a sandy beach that, at times, gets pounded by wind-driven crashing waves, recognize that the sand will likely wash in and out from the shore. A fixed dock set only on feet or skids will likely be undermined and not remain level. River currents and outgoing tides on coastal waters will also sweep sand away from the dock. Plan on setting the legs deep enough into the lake bed, seabed, or riverbed to prevent effects from wave and current erosion.
Direction of wind: If there is a significant reach to the opposite shore, even a “narrow window” between islands or other barriers, there could be enough wind from that direction to consider when planning where a boat will be moored at the dock. During your site survey, make a note as to the direction any significant wind can come from. This is useful information when floor- planning the dock so you can be cognizant of where the protective leeward side is.
Checking the ground and water depths: For a fixed dock, you’ll need to verify that the lake bed, seabed, or riverbed is stable enough so that the legs can stand firmly. In “one fell swoop,” while checking for this, you can measure the depths along the path of the dock where you expect the legs to stand. Legs will be present at the end of every section, so it will help you to know the length of dock sections you plan to use. Their length will be the unit of measure used to pace across the water with and guide where to measure the depths. During your survey over the water, you can also determine the total dock length required to reach the desirable capacity for boats and all activities you have in mind. Once this information is collected, it can then be mapped out on paper to use in your planning process and to arrive at your material requirements. Unless you’re willing to wade out there or you’re replacing an old dock that is still present and safe to walk on, I would use a human-powered canoe or dinghy for this part. Additionally, have ready the following implements.
• A lifejacket.
• A flexible tape-measure to extend from shore out over the water, good for the overall length of the dock. I carry a 100-footer (30 meters) with me.
• A rigid tape-measure, for checking the depths, one that you don’t mind getting wet. Even better, use a length of 1 ½-inch (3.81-centimeter) PVC pipe, marked and numbered every 6 inches (15.24 centimeters) if you expect to be in deeper than 5 feet (1.52 meters). For shallow water, less than 5 feet (1.52 meters), you could mark the oar or canoe paddle the same way provided the marks won’t bother you later.
• Have a pencil, notepad, and graph paper ready.
• A friend to assist will come in handy.
For this exercise, choose an occasion when the water is calm and there is good visibility. Again, I recommend a small boat for this, such as a canoe, and the operator to be skilled with its handling. Take the measuring implements into the boat with you, leaving the hooked end of the flexible tape measure to be held firmly by your helper on the shore. He or she should hold it at the spot where the dock will meet land, such as where the ramp rests on the bank. Have your helper take the pencil and notepad so your hands are free to handle the boat while measuring. You can then call out the information for your helper to jot down.
Before getting too far offshore, agree with your helper on a landmark that is on the opposite shore, in line with the direction you want your dock to go. With that, your helper can visually line up your position with it and verbally guide you to keep your measurements on course. While holding the flexible tape measure taut between you and your helper, begin moving away from the shore, stopping where the first legs will stand or at the end of what would be the first section. Then measure the depth while checking for bottom stability and call out the information to your helper. Be sure to clarify the distance out and its respective depth.
Consider the direction of predominant winds that your waterfront is exposed to. Boats usually weather the wind