Setting Posts For A Boat Dock: A Comprehensive Guide

Setting posts for a boat dock is a labour-intensive task, but with the right tools and knowledge, it can be done successfully. The depth of your dock posts is crucial for stability and should be determined by factors such as water depth, freeze lines, and seabed conditions. Most professionals recommend driving posts at least 4 to 6 feet into the seabed, but they should be buried below the frost line in areas with freezing water to prevent frost heaving. When it comes to materials, pressure-treated wood is a cost-effective option, but plastic-coated wood, heavy-duty aluminium, and concrete are also viable choices. If you're working on sandy or silty lake beds, jetting out the water is a good method to sink your posts. Alternatively, you can use heavy-duty PVC pipes to form concrete posts, providing stable footers for your dock.

Choosing the right materials for your posts

Type of Wood

Pressure-treated wood is a popular choice for dock posts due to its cost-effectiveness and durability. The treatment process involves preserving the wood with special chemicals, making it more resistant to harsh outdoor conditions, including constant exposure to water and wood-eating organisms. When selecting pressure-treated wood, opt for round posts as they are easier to install and last longer since the interior of the wood is not exposed.

However, keep in mind that pressure-treated wood may be prone to checking, warping, and splitting in environments with constant moisture. Additionally, paint or stain may peel or chip over time. If you want to explore other options, modified wood is a great alternative. It offers enhanced durability and water resistance without the need for staining.

Diameter of Posts

The diameter of the posts will depend on the weight of your boat dock. For docks weighing less than 10,000 pounds, choose posts with a diameter of 6–8 inches (15–20 cm). If your dock weighs more, select posts with a diameter of 10–12 inches (25–30 cm). Ensure you have enough posts to place them about every 10 feet (3 meters) along the dock on both sides for adequate support.

Alternative Materials

While wood is a common choice for dock posts, there are alternative materials available. Plastic-coated wood and heavy-duty aluminium posts are options to consider. Additionally, you can opt for concrete posts, which provide stability and durability. Concrete posts are created by pouring concrete into heavy-duty PVC pipes. This method ensures that the posts are sturdy and can withstand the elements.

Environmental Conditions

Consider the environmental conditions of your specific location when choosing materials for your dock posts. Factors such as water depth, freeze lines, and seabed conditions will impact the type of material you select. For example, if your location experiences freezing temperatures and the risk of frost heaving, ensure the posts are buried below the frost line to prevent movement.

Additionally, if you are setting the posts in sandy soil, you may want to use a water jet or power washer to clear away sand and silt so the posts can be securely anchored. In muddy or silty beds, concrete posts may be a more stable option.

Determining the appropriate depth for your posts

The depth of your dock posts is crucial for the stability and durability of your boat dock. The general rule of thumb is to drive your dock posts to a depth of at least 4 to 6 feet into the seabed. However, this may vary depending on specific conditions such as water depth, freeze lines, and seabed conditions.

If you live in an area where the water freezes, it is important to bury the posts below the frost line to prevent frost heaving, which can cause movement and damage to your dock.

For locations with sandy or silty soil, jetting is recommended. This involves using a high-powered water jet to clear away sand and silt, allowing the posts to sink to the desired depth. If you are unable to access a water jet, a power washer or high-pressure garden hose can also be used, although the process may take longer.

For muddy or silty lake beds, concrete footers are a more stable option. This involves using heavy-duty PVC pipes, with one pipe fitting inside the other, to form the concrete posts. The smaller pipe, which is typically 6 to 8 inches in diameter, is placed inside the wider pipe, which is typically 12 to 18 inches in diameter. Concrete is then poured into the smaller pipe, and as it fills up, the smaller pipe is slowly pulled out, allowing the concrete to form the base of the posts.

When determining the appropriate depth for your dock posts, it is important to consider the specific conditions of your location and seek professional advice if needed.

Preparing the location for post installation

Before installing posts for your boat dock, it's crucial to carefully prepare the location to ensure a sturdy and long-lasting structure. Here's a step-by-step guide to help you through the process:

• Understand the conditions: Begin by assessing the specific conditions of your location, including the water depth, type of seabed or lake bed, and any potential obstacles underwater. This information will guide your installation process and help you choose the most suitable installation method.
• Mark the locations: Once you have a clear understanding of the conditions, use a marker buoy to indicate the exact position where each post will be installed. This step ensures that your posts are placed accurately and aligned correctly.
• Gather the right tools and materials: Depending on your chosen installation method, gather the necessary tools and materials. For instance, if you plan to use the jetting method, you'll need a water jetter or a high-pressure water pump. If you opt for concrete footers, you'll require heavy-duty PVC pipes, concrete, and post-hole diggers.
• Choose the right type of posts: Select the most suitable type of posts for your boat dock. Pressure-treated wood is a popular and cost-effective option, but you can also consider plastic-coated wood, heavy-duty aluminium, or concrete posts. Round posts are generally recommended for their durability and ease of installation.
• Prepare the posts: Before installation, prepare the posts by cutting them to the appropriate height. The posts should be tall enough to hold the dock 3–4 inches (7.6–10.2 cm) above the highest expected water level, taking into account tides, flooding, or heavy rainfall.
• Recruit help: Installing posts for a boat dock can be a labour-intensive task, so it's advisable to enlist the help of volunteers or workers. This will make the process more manageable and ensure that tasks requiring multiple people can be efficiently completed.

By thoroughly preparing the location and following these steps, you'll be well on your way to successfully installing the posts for your boat dock. Remember to always consult with professionals or experienced individuals if you have any doubts or concerns during the process.

Driving the posts into the seabed

Preparation:

Before driving the posts, it's important to understand the water depth, seabed type, and any potential underwater obstacles. Mark the exact location of each post using a marker buoy. If you're working in a team, ensure everyone is on the same page regarding the plan.

Choosing the Right Posts:

The type of posts you select will depend on various factors, including your budget and the specific conditions of your location. Pressure-treated wood is a popular and cost-effective option, but it may be prone to warping and peeling over time. Alternatively, you can consider plastic-coated wood, heavy-duty aluminium, or concrete posts. Round posts are generally easier to install and tend to last longer, as the wood isn't cut off, exposing its interior.

Driving the Posts:

The standard recommendation is to drive the posts at least 4 to 6 feet into the seabed. However, this may vary depending on the water depth, freeze lines, and seabed conditions at your location. If you're in an area where the water freezes, ensure the posts are buried below the frost line to prevent movement caused by frost heaving.

If you have access to a pile driver, a piece of heavy equipment that applies downward force, you can use it to drive the posts into the seabed. Make sure the posts remain plumb and level throughout the process.

If you don't have a pile driver, you can use a water jet or a power washer to clear away sand, silt, or mud. Stand the post in the desired spot and use the water jet to remove the material from underneath, allowing the post to sink to the desired depth. Alternatively, you can use a sledgehammer to pound the posts into the seabed. This method is more feasible in harder seabed conditions.

Securing the Posts:

Once the posts are driven into the seabed, you'll need to stabilise them. This can be done through bracing or by encasing the post in a cement footer for added stability. If you used a water jet to sink the posts, you can use the jet to push some of the displaced dirt back around the post for added stability.

Additional Tips:

• Regularly check the alignment of the posts during the driving process and make adjustments as needed to maintain a vertical position.
• Consider using auger posts, which are long metal screws that burrow into the seabed, providing a secure anchor for the dock.
• If you opt for concrete posts, you can use heavy-duty PVC pipes to form them. This involves using two different diameters of pipe, one inside the other, and pouring concrete into the smaller pipe as it's slowly pulled out, creating a stable base for your posts.

Remember to consult with professionals or experienced individuals if you have any doubts or concerns during the process.

Securing and stabilising the posts

Once your posts are in place, it's time to secure and stabilise them. This can be done in a few different ways, depending on the materials you are using and the conditions of your location. Here are some methods to consider:

• Bracing: You can brace the posts by attaching a metal brace to the piling 4-6 feet above the bottom. This will prevent the post from sinking further into the lakebed.
• Cement footer: In some cases, you may need to encase the post in a cement footer to add extra stability. This is especially useful if you are installing the dock in an area with challenging weather conditions, such as freezing temperatures.
• Jetting: If you are building your dock in sand or silt, you can use a water jet or a power washer to remove the sand or silt around the post. This will help to sink the post deeper into the lakebed and secure it in place.
• Concrete and PVC pipe: Another stable option is to use heavy-duty PVC pipe and concrete to create posts. Place a smaller-diameter PVC pipe inside a larger one and pour concrete into the space between them. As the concrete cures, it will form a solid post that can support your dock.
• Auger posts: Auger dock posts are long metal screws that burrow into the seabed, providing a secure anchor for your dock. You can attach an auger to the bottom of your dock post, position it vertically, and then screw it into the ground using a clockwise motion.

Remember to always consult with a professional or an experienced person if you're unsure about the best method for securing and stabilising your dock posts. The specific conditions of your location will also play a crucial role in determining the most suitable approach.

Frequently asked questions