What’s the difference between Coosa Bluewater and Coosa Nautical?

Coosa Bluewater vs. Coosa Nautical Composite Panels

Coosa Bluewater and Coosa Nautical are closed-cell, fiberglass-reinforced polyurethane composite panels commonly used as rot-resistant alternatives to marine plywood. Both product lines resist water absorption, mold, mildew and dimensional changes, but they differ in fiberglass reinforcement, stiffness, weight, strength and intended application.

The main difference is that Coosa Bluewater contains both continuous-strand fiberglass and woven fiberglass reinforcement. Coosa Nautical contains continuous-strand fiberglass reinforcement without the additional woven fiberglass layers. At an equivalent density, a Bluewater panel will generally be stiffer than a Nautical panel.

What Is Coosa Bluewater?

Coosa Bluewater is the more heavily reinforced Coosa panel series. The additional woven fiberglass reinforcement gives Bluewater greater flexural strength and stiffness, making it suitable for demanding structural marine applications.

Common Coosa Bluewater applications include:

• Fiberglass boat transom replacement
• Stringers and engine beds
• Structural decks and floors
• Bulkheads
• Hatch lids and seat bases
• Equipment mounting areas
• Areas with wider unsupported spans
• Structural replacements for marine plywood

The Bluewater series is available in multiple densities, including Bluewater 20, Bluewater 26 and Bluewater 32. Higher-density panels generally provide greater compression strength, stiffness and fastener retention, but they also weigh more.

What Is Coosa Nautical?

Coosa Nautical is a lighter and generally more economical fiberglass-reinforced composite panel. It uses layers of continuous-strand fiberglass throughout a closed-cell polyurethane foam matrix but does not contain the woven fiberglass reinforcement used in Bluewater panels.

Nautical panels are often selected for applications where weight reduction is important and the panel does not need the same stiffness or structural reinforcement provided by Bluewater.

Common Coosa Nautical applications include:

• Boat cabinetry and furniture
• Interior partitions and cabin walls
• Lightweight bulkheads
• Hatch liners and interior panels
• Deckheads and overhead panels
• Low-stress flooring and decking applications
• Light structural or semi-structural components

The Nautical series includes several densities, such as Nautical 15, Nautical 20, Nautical 24 and Nautical 30. The correct density depends on the required strength, panel span, support spacing, fastener requirements and expected load.

Coosa Bluewater and Nautical Comparison

Which Coosa Board Should I Use for a Transom?

Coosa Bluewater is usually the starting point for a structural transom replacement because of its additional fiberglass reinforcement and greater stiffness. Bluewater 26 is commonly considered when replacing marine plywood, while Bluewater 32 may be evaluated for applications requiring greater density, compression strength or fastener retention.

The correct panel cannot be selected by the boat length alone. Transom design, engine weight, horsepower, mounting configuration, original laminate schedule, panel thickness, support structure and expected loads must all be considered.

Can Coosa Nautical Be Used Structurally?

Coosa Nautical can be used in light structural and semi-structural applications when the selected density, panel thickness, support spacing and fiberglass laminate are appropriate. However, it should not automatically be substituted for Bluewater in a transom, stringer or other highly loaded component simply because both products are Coosa panels.

Nautical panels are often a good choice for weight-sensitive applications that do not require the additional woven fiberglass reinforcement and stiffness of Bluewater.

Does Coosa Board Need to Be Fiberglassed?

Whether Coosa Board needs to be fiberglassed depends on the application and the required finished laminate. In most structural boatbuilding and repair applications, the Coosa panel becomes part of a complete fiberglass laminate and must be properly bonded and glassed into the surrounding structure.

The panel itself does not rot like plywood, but that does not eliminate the need for proper bonding, edge treatment, fiberglass reinforcement and load distribution. Fasteners should not be relied upon as the only method of attaching a structural Coosa panel.

Factors to Consider When Choosing Coosa Board

Before choosing between Bluewater and Nautical, consider:

• The structural load placed on the panel
• The distance between supports
• Whether the load is spread across the panel or concentrated in one area
• The required panel thickness
• The fiberglass laminate applied to each side
• Fastener and screw-retention requirements
• Whether the component may experience impact or vibration
• The importance of reducing weight
• The original boatbuilder’s construction and engineering

Get Help Choosing Coosa Bluewater or Nautical

Fiberglass Florida supplies Coosa Board for transoms, stringers, decks, bulkheads, boat interiors and other marine construction and repair projects. Our Rockledge location serves Brevard County and Central Florida, while our Stuart location supports Martin County, the Treasure Coast and surrounding areas.

For help choosing a Coosa panel, provide the intended application, required thickness, panel dimensions, distance between supports, expected loads and details about the original construction. Our team can help compare available Coosa products and select the most appropriate material for your project.

Important: Fiberglass Florida can assist with product selection, but structural repairs and modifications must be evaluated and completed according to the boat manufacturer’s requirements or by a qualified marine professional when appropriate.