Читать книгу Building Your Own Dock - Sam Merriam - Страница 23

Now that we’ve considered the best conditions for a fixed dock, let’s see if one will be a good fit for your waterfront. When I visit a shorefront to measure for a fixed dock, I am sometimes unfamiliar with the body of water, so I will start with these questions.

• Where should the dock begin at the shore?

• Where will I set the first set of dock legs?

• Is the water level somewhat stable here?

• What is the exposure here to waves and current?

• What direction does the predominant wind come from and is it formidable?

• Is the ground firm and stable?

• Will it be in an acceptable depth range?

Perhaps you’ve had plenty of time to become familiar with the waterfront where you’ll be installing a dock; in that case, you’re ahead of the game. Almost half the time, when I meet with people about building a dock, they are unfamiliar with the nature of their shoreline, perhaps they just bought the property, so a little detective work is in order.

Choosing a suitable location: Quite often there is clearly one place the dock can go off a property, be it a narrow lot, code-restricted area, or proximity to adequate depths. Otherwise, if your waterfront gives you options, here are some things I would consider. Begin with a comfortable elevation off the water. If possible, avoid having to build stairs or an extra-long ramp that will require needless climbing when there is a lower approach nearby that could be used instead. See that the location provides the right depth for your boat and activities while being free of obstacles. If there is a barrier with a leeward side from wind and storms, take full advantage of it. For privacy’s sake, keep a comfortable distance from the neighbor’s dock. The huge pine tree at the water’s edge could offer shade for the dock if that’s your thing, but keep in mind that it could also rain sap and soot. A dock at the side of a swimming hole is preferred over a dock that is in the swimming hole. The same can be said for the scenic view; it is better to keep the dock on the side rather in it. I guess that depends on what you’d rather look at, the dock and boat or the water and mountains behind them. Having it where you can see it without spoiling the vista would be ideal. Finally, make sure you include your significant other on this one. It’s much easier to move an idea than the real thing.

Establish the location of dock legs nearest to the shore: Their location will set the course for placement of all the other dock legs. Most of the DIY docks in this book are comprised of standard- size sections that become building blocks adjoining to one another. Each section typically gets two legs at its farthest end. It may be your preference to place the first set of legs above the shoreline to support the shore end of the dock section or place them out into the water at a distance so that the shore end of the first section rests on dry land.

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 better when kept on the dock’s leeward side.

As you move out, jab at the bottom with your paddle or PVC pipe to check for firmness. A firm bottom may have a small layer of muck over the top; that won’t matter. If there is deep muck on the bottom, such that you could sink into it, up to your shins, then that may be a game changer for the classification of dock you’ll choose. Nevertheless, proceed with your site survey as you’ll need to know the details of your submerged waterfront before choosing any option. You should also make note of any significant obstacles as you move along, such as stumps and boulders. Have your helper write down what it is, its distance under the water’s surface, and its distance from the shore with any other references as to its location. Use a GPS device or app for this if you have one. If visibility into the water is poor, use your paddle or PVC pipe to sweep around and find obstacles that are not visible. If an immovable obstacle will impede the installation or intended use of the dock, you may consider setting over from it in another spot and repeating the survey there.

A marked paddle for measuring depths is a great tool for probing the bottom while checking for hardness and for obstacles that need to be included in your plan. For depths greater than the length of your paddle, consider a marked length of PVC pipe.

Continue to drift away, toward the location of the next set of legs. Once over the spot, hold the tape measure taut and get the next depth measurement while checking for firmness. Repeat this procedure for each additional dock section that may be in your plan. For docks that extend over to the side, such as an “L” or “T” shape, set over to check that the depths there are no different than what you measured along the main portion. Keep in mind that most power boats need a minimum of 3 feet (91.44 centimeters) in depth for the stern end. If there is potential for severe chop, then more distance out for greater depth may be required to prevent the pitching boat at the dock from hitting the bottom.