The design and construction of a dock, that will actually survive the next season, is a drama that has always been interesting and challenging, especially here in the Northeast. The ice and the snow will always present a challenge that no one in the south can appreciate. I have boating experiences in both New England, as well as the south, and the differences in dock building and maintenance, is on two different sides of the spectrum.
In the south, the design and construction of a dock is a simple act of placing some type of walkway or ramp out to a floating or stationary platform. In many areas, the use of driven wooden piles is the appropriate method of support, and the existence of several contractors that specialize in the installation of piles, makes the installation of a dock in the south a very simple. The longevity of the dock itself in these areas is also assumed and not a major concern. In many areas of the south, the purchase of a piece of property alongside the water will already have a dock or at least the dock pilings installed. The lack of any winter freezing and ice buildup, also takes all the fun out of designing and constructing a dock in the south!
In the northeast, the installation of pilings of wood or steel is also a popular method of dock construction. However, the existence of contractors that are capable of this installation, are not as numerous as in the south, and the existence of several lakes and ponds makes it an exceptional occurrence, if there is actually a contractor that resides on the lake or pond, that has the equipment to install these pilings. Of course, the possibility of accessing the shoreline from the mainland is a possible solution to the installation of piles; however this ability requires research and diligence, in finding this type of contractor. Most times in the north the access to the shoreline from the road is not an easy route for a pile driving machine. In addition, the expense of this procedure matches the limited access to these contractors, therefore if there are few contractors available to provide this service, the expense, of course will be high. In addition, the expectation of a pile supported dock in the south is almost a given, the existence of one on a lake or pond in the north is an exception.
This discussion does not involve the use of piles, or the hiring of a professional contractor that specializes in docks and the installation of dock pilings. This discussion focuses on the various methods of pond and lake, dock and walkway installations, that the individual property owner can perform themselves. Again, as in most of my webpages, I encourage creativity, together with common sense, in evaluating the specific conditions that your dock will be constructed upon. For this discussion I will assume that the bottom of the pond or lake is a typical New England bottom, consisting of miscellaneous materials. Normal New England lakes will have a portion of the bottom, as a sandy layer of a relatively even bottom, compromised with the typical New England rocks and boulders. In addition, it is not uncommon to find the bottom compromised of muck or silt that is unstable for any type of dock support, or combinations of stone as well as sand. I can relate to a pond that I would continually, each season try to construct a dock. This pond had every conceivable bottom imaginable, and would require a seasonal tune up of the dock, using every creative method that we could think of, to stabilize the actual walkway to the platform that was located off the shore, in the deeper water.
What are the requirements for a typical dock?
- Normally, a dock is constructed to allow access to a boat that will be docked at the end. Most boats draw a quantity of water under their hulls. The draw of a boat is dependent upon the hull design, as well as the size and weight of the boat. The heavier the boat, normally the more water that the boat requires to remain afloat, without bottoming out on the bottom of the lake or pond. The design of the hull also makes the displacement of the water under the hull different, depending upon the shape of the hull. The V hull will require additional depth to float, as opposed to the flat’s boat, or a pontoon boat. Both of these designs have a very flat surface, which sits on the water and displaces less water to float the boat. The surface area of the bottom of the boat, that actually contacts the water, will determine how deep the actual hull will sink, prior to stabilizing the boat and allowing it to float. Therefore, the wider and flatter the hull, the less depth of water is required to float the boat. The length of the dock is normally a consideration of what type of boat will be moored to the end of the dock. The deeper the boat sits in the water or the deeper the draft, the further into the water the dock will need to extend.
- In most situations the dock will consist of a length of walkway that is long and narrow. This walkway will extend out to the end where there is normally a platform. This platform is constructed wider than the walkway and provides a gathering area for individuals to sit or sunbath enjoying the lake, pond or ocean. In addition to the ability to congregate at the end of the dock, the additional space makes the access to the boat, as well as the ability to load and unload the boat easier due to the wider section of the dock.
- There are various methods of supporting the walkway and the dock. These can consist of the following means of support.
- Total floatation. In this method, the walkway and the platform are supported by floatation items such as barrels, styro-foam inserts or specially made floatation devices, specifically designed and manufactured for the dock support.
- Partial floatation. The walkway or the platform are supported by floatation devices, the other portion is supported by a rigid support that rests on the bottom of the body of water.
- Total rigid support. Both the walkway and the platform are rigidly supported with no floatation devices, only support that rest on the bottom of the lake, pond or ocean and support the structure above.
- Driven posts of metal or wood that are more easily driven than the typical wood or metal pile. These posts could be steel, wood or aluminum and would be inserted into the bottom by the brute strength of a sledge hammer or a mechanical pipe embedment piece of equipment that is used to drive the pipes down into the bottom. Another method of pipe embedment is to have a large piece of excavating equipment, push the pipe into the bottom of the body of water with the arm of the excavator. The depth of the embedded pipe is usually based upon what type of bottom is being penetrated. Typical New England soil with rocks and boulders is usually not conducive to deep penetration. Sandy, silt or mud soil will allow a deeper penetration of the posts, therefore providing a more stable supporting structure.
- Individual supports that are constructed in a configuration similar to sawhorses. These supports are constructed to allow the walkway and the platform to sit on the top of these supports while the weight of the walkway and platform keep the supports firmly on the bottom of the body of water. In many instances, these supports are constructed to allow the installation of concrete blocks or other objects of weight to be piled within the supports. This allows the installation of the support to remain on the bottom, prior to the placement of the walkway and the platform. Remember, if the support is constructed of wood, it will float prior to having any weight on the top of it. The installation of weight within the supports themselves will allow them to remain in stationary in the water as the walkway and the platform is placed on the top. In many instances the connection of the top piece of walkway and platform is achieved with a rope tied to the top of the support and the bottom structure of the walkway, or some type of mechanical connection that will hold the two elements together. The development of large zip ties, has now allowed these zip ties to easily connect the two elements of the dock construction.
- Special considerations for dock construction.
- Will the dock be constructed to remain in the water all year long, or will it be a seasonal dock that will be removed from the water each fall? In the northeast, the majority of docks are removed from the water after the summer’s season of use. There are several reasons for this removal. The damage to the dock is much less severe, if the actual walkway and platform are removed from the water. If the supports are also removable, meaning they have not been driven into the bottom, their removal is also a positive maintenance aspect of keeping the dock from being damaged during the winter months.
- On many bodies of water, the depth of the water varies according to the season. On some lakes and ponds that are controlled by manmade dams of concrete or earth, the ability to actually drop the water during certain seasons could be a factor on your dock maintenance and longevity. If the water is dropped considerably, for whatever reason, the docks walkway, platform and supports could be exposed to the weather and the elements. This could cause severe damage to the dock. If the water is raised, then the wave action as well as the ice and snow may cause substantial damage. It is recommended that to properly manage your dock, you learn the schedule of water levels on your particular body of water.
- If you are in a region where there is severe icing, wind and snow, then the damage to your dock, if left in the water, can be tremendous. Unless you have experienced the power of a wind driven ice breakup on a lake or pond, you will not believe the forces that can be generated against you dock. Once the ice breaks up, the movement of the large pieces of ice can ruin the strongest of docks.
- Again, if you are in a region of severe icing, the uplift of the ice, as it freezes, can cause considerable damage. During the winter months in severe climates, the water expands as it freezes, and will cause substantial harm to docks and dock supports. I have witnessed docks totally lifted off of their supports by the freezing of the water’s surface. The forces that will develop with freezing water is unbelievable, and once witnessed, will indicate the need to remove the docks and their supports during the ice season. This removal will allow you to continue to use these elements for a dock off your waterfront, once the weather warms up.
- The walkway and the platform should be anchored to the bottom, of the body of water, to prevent them from floating away during a storm. Even in the summer months, a strong thunderstorm can create large waves and wind on the smallest body of water. These waves and wind can push the walkway and platform off the supports, or simply push the entire dock structure towards the beach. It is not uncommon to find your dock floating away, or parallel to the shoreline, after a large powerful thunderstorm. In addition, the threat of hurricanes during the fall season is another reason to anchor the docks as firmly as possible to the bottom. Everyone that creatively constructs a dock has different methods of securing the dock. However, I feel the use of a large concrete block, preferably the 16 inch, largest standard block, full weight, not light weight, should be used to stabilize the dock and hold it in positon. The actual connection to the dock itself can be simply a tied connection or a sophisticated clipped type fastener. In any case, it is important to anchor your dock to prevent it from floating away. The more sophisticated of us will use a chain connection, others may simply use rope, I would recommend a minimum of ½” nylon rope be used.
- The walkway and platform should be constructed in a fashion, and with a material that is not slippery when it gets wet. Do not treat the top of the walkway or platform with a heavy coat of paint or slippery sealant. It is important that the surface remain rough, and of a nonslip material. There is nothing more tragic than a small child, excited and running on the dock who trips and falls. This can ruin a beautiful day at the lake!
- The walkway and platform should be constructed of a material that does not have the tendency to contain wood slivers or any other type of splintery surface. The normal person using the dock will probably be in bare feet, and the insertion of a large splinter, is another way to ruin a perfect day!
- The walkway and the platform should not be constructed of any material that absorbs the heat of the sun. The surface should not be dark, but should be a light colored material that does not become hot when sitting in the sun. The aluminum decks are wonderful; however make sure that the aluminum is treated with a surface coating, sufficient to reduce the amount of solar heat that the decking absorbs from the sun.
- The entrance to the walkway from the shoreline must be carefully aligned, to prevent tripping, as individuals enter and exit the walkway. This is sometimes a difficult area of the dock, due to varying shoreline configurations. In many cases the use of a separate platform to provide a safe and even entry to the walkway onto the dock is necessary. This determination will need to be done individually, based upon the water level as well as the makeup of the shoreline.
- If the dock is to be removed after the season, the design of the dock and its components must consider the weight of the individual pieces, as well as the ability to actually remove and reinstall the pieces. This is an important part of a good dock design. If the individual pieces are too heavy to handle safely, the dock will not be taken in and reinstalled due to its difficulty. Therefore this is an important consideration when designing the walkway and the platform. It must be easily removable and reassembled.
- The marking of the pieces of the dock must be clear and easily read in the springtime when the dock is to be reassembled. If the pieces become mixed up, and it cannot be determined which piece is first, second, etc. then the reassembly can be extremely frustrating.
As can be determined by reading this webpage, I have personally had a lot of experience with the construction of difficult dock assemblies. I have also had the actual issues that I warn against, happen repeatedly to me, as I attempted to create the perfect dock. However, the construction of a dock and its supports can be an extremely rewarding activity for the family, and especially a father and son! The interaction, as you attempt to figure out why last year’s dock was ruined entirely and why the neighbors dock remained intact, are the humorous facets of growing up and provide fond memories. I can remember the time my Dad and I tried to actually pour concrete piers with steel inserts to accept structural steel supports for our dock. We spent countless days performing this work. It failed miserably, and our neighbor, who happened to be a banker (no negative connotation inferred) had built a rickety dock out of old lumber and nails, our neighbors dock lasted the winter and ours was totally and completely destroyed. Those are the type of memories that will last a lifetime!
Dock construction is better left to the experts; however, if you want an engineering challenge, as well as a fun family experience, try to build one yourself with your sons. It will be a lasting experience and I am sure full of more laughs than injuries! Of course, your daughters will probably have the best ideas for this type of construction!
One more thing! You don’t need a level when constructing a dock. Water has a general tendency to provide a level surface, so the simply measuring off the top of the water will provide the accuracy of the most expensive level.
In addition, the installation of the springtime dock is extremely exhilarating and stimulating, especially in New England in May!