Revolutionizing Coastal Livelihoods: Composite Sandwich Fishing Boats

A New Wave in Traditional Boatbuilding

In the coastal community of Desa Lapang Barat, a quiet revolution is underway that promises to transform the fishing industry. For generations, local fishermen have relied on wooden boats, facing increasing challenges from rising material costs and limited timber availability. The emergence of composite sandwich technology offers a innovative solution—creating fishing boats that are not only lighter and more fuel-efficient but also stronger and more durable than their traditional wooden counterparts.

This groundbreaking approach to boatbuilding represents more than just technical innovation; it embodies a sustainable future for coastal communities where fishing is both cultural heritage and economic necessity.

By combining modern composite materials with accessible construction techniques, this technology empowers local fishermen with vessels that enhance their productivity while reducing environmental impact. As we explore this transformative technology, we'll uncover how simple materials and methods are creating waves of change in traditional fishing communities.

Lighter Construction

Reduced weight for better fuel efficiency

Enhanced Durability

Stronger than traditional wooden boats

Sustainable Materials

Reduced environmental impact

The Science Behind Composite Sandwich Boats

What Are Composite Sandwich Materials?

At its core, composite sandwich construction draws inspiration from nature's own engineering marvels—much like how bird bones and honeycomb structures achieve remarkable strength with minimal weight. This approach creates a material that outperforms traditional wood in nearly every aspect relevant to fishing boats.

A composite sandwich panel consists of three key layers: two strong outer skins and a lightweight core material sandwiched between them. The outer skins, typically made from fiberglass reinforced with bamboo or other fibers, handle the primary structural stresses, while the core material provides stiffness and buoyancy without adding significant weight ⁷ .

Key Materials and Their Functions

Reinforcement Fibers

Fiberglass remains the most common reinforcement material, available in various weaves like E-glass for general use and stronger S-glass for high-performance applications . Natural fibers like bamboo are increasingly used in combination with fiberglass, creating sustainable composites that leverage local materials ⁷ .

Core Materials

Polyurethane rigid foam serves as an excellent core material, providing buoyancy and structural height while remaining lightweight ⁷ . Alternative core materials include Divinycell PR 200, which contains up to 45% post-consumer recycled PET, adding an eco-friendly dimension to boat construction ⁵ .

Resin Systems

Polyester resin is commonly used for its affordability and good adhesive qualities, with isophthalic polyester offering superior water resistance for marine applications . For enhanced durability, vinyl ester resin provides better resistance to water absorption and vibrations.

The Hand Lay-Up Technique: Bringing Technology to the Village

Accessible Boatbuilding for All

The hand lay-up method stands as the cornerstone of making composite sandwich technology accessible to traditional communities. This technique doesn't require sophisticated equipment or extensive technical training—making it perfectly suited for implementation in villages like Desa Lapang Barat ⁷ .

Unlike industrial boat production that demands expensive molds and factory settings, the hand lay-up approach can be mastered with basic training and minimal infrastructure. This democratization of technology allows local fishermen to actively participate in building their own vessels, fostering skills development and community ownership.

Step-by-Step Construction Process

Core Formation

The boat's hull shape is created using polyurethane rigid foam as the core material. This is formed by reacting polyisocyanate and polyol liquid directly in the mold, where they expand to create a solid foam structure ⁷ .

Reinforcement Lay-Up

Fiberglass cloth or mat, often combined with bamboo weaving, is carefully positioned over the core material. The specific weave and weight of the fiberglass (typically 4-15 ounces per square yard for cloth, up to 48 ounces for roving) determines the final strength characteristics .

Resin Application

Using brushes and rollers, the resin system is applied to saturate the reinforcement fibers completely. Corner rollers help eliminate air bubbles in tight spaces, while aluminum rollers with deep grooves ensure even resin distribution on flat surfaces ⁶ .

Curing and Finishing

The resin is allowed to cure, forming a rigid composite structure. The boat is then finished with additional components—wooden elements for specific fixtures, PVC pipes for outriggers, and finally, a protective gelcoat layer that provides UV protection and a glossy finish ⁷ .

This process requires approximately 12 person-days of labor to complete a single fishing boat, making it highly feasible for community-based production ⁷ .

Essential Tools and Materials for Composite Boatbuilding

Item	Function	Specific Types Used in Boatbuilding
Reinforcement Materials	Provides structural strength and durability	Fiberglass cloth/mat, bamboo weaving, woven roving ⁶ ⁷
Resin Systems	Binds reinforcement fibers into solid composite	Polyester resin (orthophthalic/isophthalic), vinyl ester, epoxy resin ⁶
Core Materials	Creates lightweight, stiff structure	Polyurethane rigid foam, Divinycell PR 200 (45% recycled PET) ⁵ ⁷
Gelcoat	Provides waterproof, UV-resistant finish	Isophthalic polyester-based gelcoat
Catalysts/Hardeners	Initiates and controls resin curing process	MEKP (methyl ethyl ketone peroxide) for polyester/vinyl ester resins ⁶
Application Tools	Enables proper material placement and consolidation	Brushes, aluminum rollers, corner rollers, squeegees ⁶
Safety Equipment	Protects workers from chemical exposure	Gloves, respirators, safety glasses ⁶

Material Advantages

High strength-to-weight ratio
Excellent durability in marine environments
Reduced maintenance requirements
Thermal and acoustic insulation properties
Design flexibility for optimized hull shapes

Economic Benefits

Lower fuel consumption due to lighter weight
Extended service life reduces replacement costs
Minimal maintenance requirements save time and money
Local production creates employment opportunities
Improved catch preservation increases income

Material Performance: Testing the Composite Sandwich

Putting Materials to the Test

Before implementing any boatbuilding program, understanding material properties through standardized testing is crucial. The Polimi Sailing Team's approach to validating structural model parameters provides an excellent framework for such assessment ⁵ .

Through tensile tests conducted according to ASTM international standards (D3039 for tensile properties and D3518 for shear response), researchers can precisely quantify material capabilities. These tests subject composite samples to controlled stress until failure, measuring key performance indicators including tensile strength, elasticity modulus, and shear strength ⁵ .

For community-based projects, simplified versions of these tests can verify that locally produced composites meet the necessary requirements for fishing vessel construction. This scientific validation ensures safety and performance before fishermen entrust their livelihoods to these new materials.

Performance Data and Analysis

Material Type	Tensile Strength (MPa)	Elastic Modulus (MPa)	Shear Strength (MPa)	Key Characteristics
Basalt Fiber (0°)	802-874	39,062-39,608	N/A	High strength along fiber direction ⁵
Basalt Fiber (90°)	16.7-17.14	13,470-15,701	N/A	Lower strength perpendicular to fibers ⁵
Basalt Fiber (±45°)	N/A	N/A	19	Balanced shear resistance ⁵
Polyurethane Foam Core	Variable	Variable	Variable	Lightweight, buoyant, provides thickness ⁷
Traditional Wood	Varies by species	Varies by species	Varies by species	Natural material with inconsistent properties ⁷

Performance Insights

The data reveals several advantages of composite materials. The high tensile strength in the fiber direction (0°) demonstrates why these materials can withstand the significant stresses encountered during fishing operations. Meanwhile, the consistent shear strength ensures the boat maintains structural integrity under twisting and bending loads.

Implementation Framework for Community Training

Building Local Capacity

Successfully introducing composite sandwich boatbuilding technology to traditional fishing communities requires a carefully structured training program. The experience from similar initiatives suggests that a 12-person team can complete a boat in approximately 12 working days ⁷ .

The training program should encompass both theoretical knowledge and hands-on skills development:

Material Science Fundamentals: Understanding the properties and behavior of composites, resins, and core materials
Mold Preparation and Release Techniques: Ensuring clean separation of finished boats from molds
Precise Measurement and Mixing: Calculating correct resin-to-hardener ratios for optimal curing
Lay-Up Skills Development: Mastering the technique of applying reinforcement layers and resin without creating voids or dry spots
Quality Control and Troubleshooting: Identifying and addressing common issues like air bubbles, improper curing, or delamination

This comprehensive approach ensures community members not only replicate the process but truly understand the principles behind it, enabling them to adapt and innovate as needed.

Resource Planning and Management

Resource Category	Specific Items	Quantity for Standard Fishing Boat
Material Resources	Polyurethane foam components, fiberglass cloth/mat, resin system, gelcoat	Varies by boat size (documented in project planning) ⁷
Tooling & Equipment	Brushes, rollers, mixing containers, safety gear, basic woodworking tools	Standard set for 4-6 person work team ⁶ ⁷
Human Resources	Trained technicians, assistant laborers, quality supervisor	12 person-days total labor ⁷
Infrastructure	Sheltered workspace with ventilation, material storage, mixing station	Basic covered area of approximately 50m² ⁷
Time Allocation	Mold preparation, core formation, lay-up process, curing, finishing	12-day timeline with parallel tasks ⁷

Sailing Toward a Sustainable Future

The introduction of composite sandwich fishing boats in Desa Lapang Barat represents far more than a technical upgrade—it embodies a sustainable pathway for coastal communities to harness modern materials science while preserving their traditional livelihoods. This technology demonstrates how appropriate innovation can create solutions that are simultaneously technologically advanced, economically viable, and environmentally responsible.

The true measure of success for this initiative extends beyond the number of boats produced. It lies in the empowerment of local fishermen with new skills, the reduction of pressure on forest resources through decreased dependence on timber, and the enhanced safety and productivity of fishing operations. As these composite boats take to the water, they carry with them the hopes of a community riding a new wave of sustainable maritime technology.

For other coastal communities observing this transformation, the message is clear: the future of traditional fishing need not choose between heritage and innovation. Through the strategic application of composite sandwich technology, tomorrow's fishermen can enjoy the best of both worlds—preserving cultural traditions while sailing confidently toward a more sustainable and prosperous future.