Marina Development FAQ: Answering owners’ challenging site questions
July 6, 2018
Whether you are an investor, developer, owner, operator or just someone interested in the industry, this is one marina development FAQ you won’t want to miss. The pros at Bellingham Marine (and a few of the company’s trusted engineers) tackle owners’ top 12 challenging site questions.
- Extending existing docks
- Mitigating wave from boat traffic
- Building for high density
- Building and operating in freezing temperatures
- Building in tropical, high-salinity environments
- Rebuilding on a tight budget
- Placement and design, launch docks for human-powered craft
- Options for meeting grating requirements and bans on treated wood
- Building for mixed-use
- Dock that will ground out at low tide
- Dealing with debris on rivers
- Extending pile height
If you don’t find the answers to your question, contact us. Every site is unique and comes with its own questions. We love to talk about marina design and would love the opportunity to talk with you about any questions you have.
Question 1: We plan to extend the arms on several docks once we have additional funds. What do you recommend we do when building our current docks that will make extending the docks easier and less expensive?
Docks can be thought of as Lego Blocks and are easy to extend if you plan ahead, especially if they are connected by timber walers. New piles can be added and if needed, moving piles is not as bad as you might think. Utilities can be extended from junction boxes in the existing floats and carried through existing internal utility runs. Just make sure your raceways are large enough to fit the additional wire that will be required to service your future slips. Cleats on timber walers are easy to move. All in all, it is not a daunting job to extend docks with a bit of planning and foresight.
Question 2: We have constant boat traffic on our waterway. What is the best solution for addressing wave concerns in our marina?
If you have a problem with constant boat traffic disturbing your marina, here are some options roughly in order of increasing complexity and cost:
(A) Request that a no wake zone be enforced in front of your marina or seek to get the navigation channel shifted further away from the marina. (B) Add a floating wave attenuator for protection if you don’t have one or make some upgrades to the one you have. (C) Realign an existing breakwater to intercept the waves differently. (D) It may be possible to relocate the marina entrance. (E) Reorient all the dockage so the boats are pointed into the direction of the incoming wave.
Additionally, If your marina is very “square” you may be suffering from the effects of interior wave reflection. Similarly, there may be reflection or diffraction effects from adjacent or opposing shorelines that can amplify waves from a passing boat. To identify root causes and devise a solution, contact a qualified coastal engineer.
Question 3: We want to push boat density. What configurations allow for greater density of boats in a marina basin?
Taking advantage of unique basin shapes and other features to maximize density is often simply a matter of experience. There are rules of thumb marina designers use, including double berths over single berths, minimizing fairway widths and locating boats of certain sizes in certain areas.
The issue is not just density but slips in the correct sizes and numbers that best meet demand. You will maximize revenue if the project has a proper market study and your designer selects slip mixes most likely to succeed in your market.
Density is generally controlled by fairway widths and double vs single berths. There are other factors such as headwalk and finger widths, but generally, these factors are negligible or minor impacts to overall density.
Fairway widths are a navigation issue, but can have wide ranges of acceptability depending on site conditions, boater experience, local codes and public vs private usage.
Double berths allow a marina to densify, but depending on boater preference or past experience, could be considered a negative to boaters. Sometimes guide piles can be installed between boats in double-wide arrangements to mitigate this issue without consuming much additional water space.
Question 4. How do we incorporate human powered craft into our marina most efficiently? What considerations on dock design should we take into account for launching and storing? What considerations to maximize long term dock wear and tear?
Human powered craft is a huge growing market. Access to the water should be easy and safe. We need to be careful about where we place these docks. The launch dock should be placed in an area with limited cross traffic. Parking and storage are two other important pieces of the equation.
The launch dock should be stable and offer a launching area that gets as low to the water as possible. Concrete docks are a great choice for these applications. They have a tremendous amount of live-load capacity, so they can get low to the water without jeopardizing the user’s safety.
Marine grade carpet or a hardwood deck can be added to the top of the concrete dock to improve long-term wear and tear. These finishes have the added benefit of not scuffing the bottoms of the boats and are more friendly to sit on.
If you plan ahead, you can build the launch dock into the walkway. Retrofitting an existing marina is an option too. A physical connection can be made between the two docks or the launch dock can be tied off to several cleats.
Question 5: Our marina experiences freezing temperatures in winter. What type of dock system is best suited for cold climates? What operational standards should we adopt to ensure our marina can endure the winter months without damage?
In cold climates where there is the potential for snow and ice, and the docks are kept in the water, the concrete Unifloat is the best product. It provides the most stability and has superior anti-slip properties. The Unifloat uses a high quality concrete that has been specifically designed to last in cold climates.
The first wintery condition that must be dealt with is snow removal. Alaskan marinas can teach us a lot about how to get the snow and ice off the docks without damaging the surface. Snow blowers and sweepers are popular tools. The most common way to deal with icy conditions is with sand or pea gravel. Rock salt and other de-icing agents are not recommended and will cause long-term damage to the dock surface.
In freshwater locations, bubblers placed around marina can keep the water from freezing around the docks. Thick-walled concrete docks add toughness.
In locations with moving ice or where water can freeze solid, a removable timber or metal frame system is recommended. Look for a model that is designed for ease of installation, removal and storage. If your docks will be left in the water, and you have moving ice, you may need a debris deflector. Moving ice generates enough force to damage the strongest of docks.
Question 6: Our marina is in a tropical, high-salinity environment. What dock building materials offer the best longevity in our climate?
In tropical and high-salinity environments, the rate of corrosion is accelerated. For materials, you want something that is resistant to corrosion. Concrete, timber and FRP composites are all good options.
In an effort to improve product longevity, Bellingham Marine has introduced several new materials designed for extra-long-life marinas in corrosive environments. The company is moving toward a completely ferrous-free concrete pontoon. This will be an ideal product for a marina in an aggressive climate. FRP thru-rods are currently standard. Corrosion-free brackets, basalt mesh and fiberglass reinforcing are next to come.
Question 7. Our docks are at the end of their useful life. We are extremely cost conscious due to our market. What dock systems are right for us?
There are ways to build with appropriate materials and level of dock required for the site that can help save money. Install heavy-duty docks in exposed areas and opt for a lighter weight system on the interior or on the fingers. You can phase your rebuild over several years. Existing piles can be reused if you place your new docks in the same footprint. In some cases, electrical equipment can be reused.
There is a huge misconception that concrete docks are more expensive than a framed dock. When it comes to cost, it is important to take the whole system (anchoring, dock, utilities and installation) into consideration. In general, framed docks require more pile. More pile can lead to a higher price tag.
Take for example a recent client in California. For them, the least expensive option was to use concrete docks where water depths permitted, and timber docks along the shallow quay wall. All docks were decked in timber to give the walkway a uniform look. The hybrid solution was less expensive than going with an all timber dock option. It came down to the cost of the piling.
Question 8: Environmental regulations in our region are tough to overcome. What options do we have for meeting strict grating requirements and bans placed on use of treated wood?
Both our concrete and framed systems can incorporate grating to meet the 50% light penetration /grating requirement. An option to comply with overwater coverage limitations is to install concrete floats for main walks and narrow timber-framed docks for fingers. Narrower finger docks help reduce over water coverage. When connected to concrete floating main walks they gain stability and longevity.
A concrete dock with an FRP waler will meet requirements prohibiting use of treated wood. A metal frame system would also work.
Question 9: We want to build a mixed-use marina to include public access, charter vessels, superyachts and more. What is the most effective way to layout our marina to ensure the marina operates efficiently and offers a quality user experience?
Separate the marina into zones. Superyachts want exclusive real estate away from public docks and charter vessels. They also need delivery access.
Public docks need adjacent vehicle parking. Charter vessels don’t usually care what is adjacent to them, but they are noisy, require a staging area for arriving passengers and need a lot of parking, so they need to be separated from other zones.
Designers must take into account access, water depths, fueling, domestic waste handling, power, prevailing wind directions and waterside and landside approaches. The idea is to create an optimal user experience in each zone. Stay flexible. Even the most experienced designers often find themselves with unintended consequences. Adopt operational plans that can be adjusted as the mixed-use tenants fill in all the spaces.
Question 10: Our facility is located on a river. We frequently deal with debris coming down the river. What options exist for debris barriers? Can something be built into the dock system?
The first step is to study the flow of the river to determine how much and what type of debris the site will see. There are many site-specific debris-deflection options. Concrete floating docks can be cast with tapered bottoms designed to pass debris under the float. This will prevent debris from accumulating against the docks. Sacrificial timber panels can be attached to the dock. You can even go as far as to armor the floats with steel panels.
The key is to look at the risk the debris (or ice) presents relative to the expense of armoring the floats. It is possible to make the walls thicker on concrete docks and increase reinforcing. However, there are limits to what can be accomplished without heavily influencing the flotation of the dock system. The most promising avenues at this point are damage tolerant panels that can be replaced at moderate expense.
Question 11: We know some of the docks in our marina will ground out. What type of dock does best in this situation? What do we need to consider?
In situations where we know the floats are going to ground out a timber dock is a safe choice. The dock has a lower draft. Timber’s ability to bend and flex without fatigue is another benefit. Docks that ground out are subject to unique forces. The timber dock handles them exceptionally well.
Metal framed systems or concrete pontoons may be a viable option as well for some sites. There are owners who have had great success with concrete floats at launch ramps. Legs, rubber buffers, or sleeper boards are placed on the underside of the pontoon and the float grounds out without a problem.
Question 12: I have an older marina and am concerned about the height of my pile. Especially with predicted rising sea levels and increased storm surges. What are my options?
If you have timber pile, the most common solution is replacement. However, some have had luck extending the timber pile by sleeving it with PE pipe and concrete grouting the top plug.
Concrete pile can be extended by attaching an additional concrete segment. The new section of concrete is stitched into the existing. This option is generally expensive. There is also the possibility of doing a steel addition on a concrete pile. This may be the cheaper of the two options. For steel pile, which many of our newer marinas in Florida and the Caribbean have, the solution is more straightforward. New sections of steel pile can simply be welded on to the existing.
The challenge is, it is not just the addition of height. When we increase the height of the pile, we are changing the lateral loading on the pile. If you are just adding several feet, you may get by with the pile’s current embedment. However, in many cases you’ll be looking at driving the pile further down to accommodate the new lateral loads placed on the taller pile.
The Bellingham Team
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Bellingham Marine built the first concrete floating dock marina in 1958 at Shilshole Bay in Seattle, Washington. This year marks six decades since that historic project.
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