23rd August, 2018

How the Marine Industry Can Make Use of Plastic Lumber

The average dock repair costs $8,027. This cost can quickly escalate to $168,000 as more pilings and lumber are required. What if you could reduce the long-term maintenance and replacement costs?

Plastic lumber is the answer. Not only does it reduce costs, but it reduces the amount of plastic going into landfills.

Plastic wood is the future of marine construction. This environmentally-friendly material provides increased strength and impact resistance in a wide range of applications.

Benefits of Plastic Woods

The major benefit of using plastic lumber over chemically-treated wood is the durability and strength. Wood treated with chemicals is still wood and will rot, splinter and deteriorate over time.

The splintering will reduce the wood’s strength, appearance and integrity. Once this process begins, the wood will need to be replaced to repair the damage.

Plastic wood does not experience the same water absorption of natural wood. This creates a more solid construction material for marine building.

Environmental Benefits

An environmentally-friendly three-stage Multi-X Technology process creates our SeaPile® and SeaTimber® recycled lumber. This process involves creating a core, then a next layer that includes includes fiberglass rebar and finally a dense outside skin.

The resulting product is durable and sustainable. It is non-polluting as there is no chemical treatment required. This makes it a better choice for permanent installation in the water. The surrounding marine wildlife will not be negatively impacted by leaching chemicals.

The Many Marine Uses

Plastic lumber is perfect for marine projects that require stand-alone pilings such as dolphin clusters and navigational aids. It provides long-term stability as a foundation for structures like bridges, docks, and marinas.

Bridge and pier protection, and bull rails that utilize plastic lumber have increased strength against impacts. Plastic lumber is the future of the marine industry with new uses being discovered each day.


Docks are traditionally made of chemically-treated wood. They then need regular maintenance and replacement to prevent them from deteriorating.

Stain and oil prevail as the leading wood water and UV protection. If a wood dock does not receive regular treatment, it could absorb water, swell, and rot causing a safety hazard and an eyesore. UV rays can also dry the wood out and cause it to splinter.

Plastic lumber is inherently resistant to both. There is no need to regularly treat it with stain or oil.

Wood has limited ability when it comes to strength under pressure. Plastic wood can be reinforced with fiberglass to surpass wood’s strength.

Santa Cruz Harbor

When a 9.0 earthquake struck Japan, the effects were felt in Santa Cruz, CA. A Tsunami surge created by the quake damaged the dock and boats in the harbor. The damage totaled over $20 million.

The redesigned replacement dock featured over 6,300 square feet of docks and piers. With the harbor’s focus on building a tough and long-lasting system was chosen.

With the HDPE plastic lumber in use, the new dock can withstand severe weather conditions. The new dock was finished in 2011 and came with a 50-year limited warranty. The 100% recycled product will provide strength against the heavy-duty use and wave action for years to come.

Fender Piling Systems

When boats bump up against the dock, they hit the fenders instead of the dock itself. Fenders provide shock and energy absorption to protect the dock and boat from potential damage. Usually, these fender piling systems are constructed out of either concrete or wood.

Concrete pilings are quite solid and unforgiving. Wood pilings are chemically treated to delay water rot and don’t provide as much energy absorption as recycled plastic lumber pilings.

When boats hit concrete, the impact damages both the  boat and concrete. This could result in chips and cracks in a boat’s hull and the concrete pilings. When boats hit wood, this can result in dents, splintering, and breakage.

Dolphin Clusters

Dolphin clusters protect bridges from impact. They provide moorings for boats in bays or inlets.

To create a dolphin cluster, multiple pilings get driven into the seabed and then strapped together at the top. Traditionally, these pilings are made of wood or concrete.

Using fiberglass reinforced recycled plastic pilings provides more strength than treated wood. The increased ability to absorb impact energy through recoverable deflection makes them ideal for these uses.

Navigational Aids

Channel navigational aids signal to boaters where safe passage is possible. These markers line either side of the channel with red and green numbered signs.

These pilings must withstand changing currents flowing around them to properly guide vessel operators. Plastic lumber pilings will last longer than their wood counterparts because they don’t absorb any water or moisture, so they won’t deteriorate. This results in lower maintenance costs long term.

Bridge Pier Protection

Often, large wood fender structures wrap around the supports of bridges and piers. This provides a protective barrier in the event of a vessel crashing into the bridge.

Recycled plastic lumber pilings provide a stronger protective guard barrier. These barriers usually experience strong tides and currents. This increased water movement corrodes the wood. A structure built of plastic and fiberglass will withstand this water movement and not rot like wood pilings.

State Road 415 Bridge

When the Florida Department of Transportation decided to expand the State Road 415 bridge over the St. John’s River, they turned to plastic lumber. The original design from FDOT included 244 concrete piles and plastic lumber whales.

Tangent won the bid and led the way in innovation by offering a solution that replaced the concrete pilings with fiberglass reinforced recycled plastic pilings. The plastic pilings provide increased energy absorption performance and greatly reduced the 244 pre-compressed concrete piles to 52 plastic lumber piles..

The overall costs for materials and installation were also reduced. The change in materials reduced the overall project timeline. The structure’s integrity has remained solid longer than the original concrete design would have.

Small Water Piles

The wood used is chemically treated to resist water absorption and rotting. As the wood sits in the water these chemicals leach into the water.

Small water piles are used in the building process for docks, piers and boardwalks. These vertical beams provide the foundational support for the structures built on top.

The purpose of the pilings is to provide increased support by channeling the weight and impact into the solid earth below the water. Recycled plastic lumber such as SeaPile® and SeaTimber® provide increased performance as small water pile material.

Tampa Electric’s Manatee Viewing Center and Boardwalk

When the Manatee Viewing Center and Teco Boardwalk were expanded, it was FiberForce® recycled plastic lumber that provided the material. FiberForce® has the size, look and feel of real lumber. This makes it perfect for the boardwalk, ADA ramps, and tower included in the project.


These low walls are parallel to each other and perpendicular to the beach. They usually begin along the start of the beach on land and extend far out into the water.

The purpose is to prevent land erosion and drifting. Using plastic lumber is ideal for groyne applications since the majority of the wall will be constantly in the water.

Traditional wood will eventually swell and splinter. This compromises its strength against the current and waves.

Bull rails

Bull rails act like a curb edging on docks. They are often found on marina and commercial docks.

These bull rails provide a place for boats to tie up when there are no cleats, or the cleats are full. They need to be sturdy and strong to support the pressure of a heavy boat pulling on them.

The fiberglass reinforced plastic lumber provides an extra level of strength that regular wood just can’t compare to. The plastic lumber won’t need maintenance and will last longer in a commercial environment.

Marina Substructure

Plastic lumber is a great alternative for wooden pilings. SeaPile® creates a long-lasting foundation.

When building decks, docks, piers, buildings, and marinas it’s important to have a solid foundation. Plastic lumber withstands the constant exposure to an extreme amount of moisture.

The Port of Hueneme

When the Port of Hueneme decided to deepen their harbor, they needed a way to reinforce the South Terminal. 

The completed project will increase the port’s depth to 40 feet. The increased depth will provide for increased marine traffic and boat size capacity through the port.

Thanks to plastic lumber, the port can maintain their green initiatives and reduce long-term maintenance costs. The reinforced lumber provides increased strength in a commercial application that wood pilings cannot.

Plastic Lumber in Marine Applications

All marine projects can benefit from recycled plastic lumber. These eco-friendly products provide increased strength because of the fiberglass strand and polymer rebar reinforcement. Marine structures built with plastic wood withstand both UV and water longer. This results in reduced maintenance costs and an increased return on investment.

Request a sample and see how plastic lumber can be an asset for your next marine project.