Marine core materials are selected based on a balance between weight, stiffness, strength, fire resistance, durability, and cost. The following tables summarize the typical density ranges and mechanical performance characteristics of commonly used marine core materials.

The values below are industry reference ranges. Actual performance depends on:

• Manufacturer
• Cell size
• Resin system
• Processing method
• Temperature conditions
• Testing standards

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1. PVC Foam Core Properties

Property	Typical Range
Density	60–250 kg/m³
Compressive Strength	0.8–6.5 MPa
Shear Strength	0.6–4.5 MPa
Shear Modulus	20–150 MPa
Water Absorption	Very Low
Operating Temperature	-240°C to 70°C
Fire Performance	Medium
Fatigue Resistance	Good

Main Characteristics

• Excellent cost-performance ratio
• Closed-cell waterproof structure
• Good process compatibility
• Widely used in hulls and decks

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2. PET Foam Core Properties

Property	Typical Range
Density	70–250 kg/m³
Compressive Strength	0.9–5.8 MPa
Shear Strength	0.7–4.0 MPa
Shear Modulus	25–140 MPa
Water Absorption	Very Low
Operating Temperature	-180°C to 120°C
Fire Performance	Medium
Fatigue Resistance	Good

Main Characteristics

• Recyclable thermoplastic structure
• Better thermal resistance than PVC
• Environmentally friendly
• Increasingly popular in European marine projects

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3. SAN Foam Core Properties

Property	Typical Range
Density	60–250 kg/m³
Compressive Strength	1.0–7.0 MPa
Shear Strength	0.8–5.0 MPa
Shear Modulus	25–190 MPa
Water Absorption	Extremely Low
Operating Temperature	-200°C to 150°C
Fire Performance	Medium to High
Fatigue Resistance	Excellent

Main Characteristics

• Outstanding toughness
• Excellent fatigue resistance
• Superior crack resistance
• Preferred for high-speed marine structures

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4. PMI Foam Core Properties

Property	Typical Range
Density	30–200 kg/m³
Compressive Strength	0.8–9.0 MPa
Shear Strength	0.7–6.0 MPa
Shear Modulus	20–250 MPa
Water Absorption	Extremely Low
Operating Temperature	-260°C to 180°C
Fire Performance	High
Fatigue Resistance	Excellent

Main Characteristics

• Ultra-lightweight
• Exceptional stiffness-to-weight ratio
• Aerospace-grade structural performance
• Very high cost

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5. Aluminum Honeycomb Core Properties

Property	Typical Range
Density	25–130 kg/m³
Compressive Strength	1.5–12 MPa
Shear Strength	0.8–6.5 MPa
Shear Modulus	30–350 MPa
Water Absorption	None
Operating Temperature	-196°C to 350°C
Fire Performance	Excellent
Fatigue Resistance	Very Good

Main Characteristics

• Extremely high stiffness
• Excellent fire resistance
• Outstanding flatness
• Requires proper corrosion protection

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6. Nomex Honeycomb Core Properties

Property	Typical Range
Density	24–144 kg/m³
Compressive Strength	1.0–10 MPa
Shear Strength	0.7–5.5 MPa
Shear Modulus	25–300 MPa
Water Absorption	Very Low
Operating Temperature	-190°C to 180°C
Fire Performance	Excellent
Fatigue Resistance	Excellent

Main Characteristics

• Ultra-lightweight aramid structure
• Excellent fire behavior
• High fatigue durability
• Widely used in military and aerospace sectors

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7. PP Honeycomb Core Properties

Property	Typical Range
Density	60–120 kg/m³
Compressive Strength	0.5–2.5 MPa
Shear Strength	0.3–1.5 MPa
Shear Modulus	10–60 MPa
Water Absorption	Extremely Low
Operating Temperature	-40°C to 80°C
Fire Performance	Medium
Fatigue Resistance	Moderate

Main Characteristics

• Economical lightweight solution
• Excellent corrosion resistance
• Easy recycling
• Suitable for non-structural marine applications

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8. Balsa Wood Core Properties

Property	Typical Range
Density	100–250 kg/m³
Compressive Strength	5–20 MPa
Shear Strength	2–8 MPa
Shear Modulus	100–500 MPa
Water Absorption	Medium to High
Operating Temperature	-50°C to 100°C
Fire Performance	Low
Fatigue Resistance	Good

Main Characteristics

• High natural compressive strength
• Excellent resin bonding
• Traditional marine composite material
• Requires strict moisture protection

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9. Comparative Density Table

Core Material	Typical Density Range
PMI Foam	30–200 kg/m³
Aluminum Honeycomb	25–130 kg/m³
Nomex Honeycomb	24–144 kg/m³
PVC Foam	60–250 kg/m³
PET Foam	70–250 kg/m³
SAN Foam	60–250 kg/m³
PP Honeycomb	60–120 kg/m³
Balsa Wood	100–250 kg/m³

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10. Comparative Structural Performance Ranking

Material	Lightweight	Strength	Fatigue Resistance	Fire Resistance	Cost
PVC Foam	Good	Good	Good	Medium	Medium
PET Foam	Good	Good	Good	Medium	Medium-Low
SAN Foam	Excellent	Very High	Excellent	Medium-High	High
PMI Foam	Outstanding	Excellent	Excellent	High	Very High
Aluminum Honeycomb	Outstanding	Excellent	Very Good	Excellent	High
Nomex Honeycomb	Outstanding	Excellent	Excellent	Excellent	Very High
PP Honeycomb	Good	Moderate	Moderate	Medium	Low
Balsa Wood	Moderate	High	Good	Low	Medium

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11. Recommended Applications by Core Material

Marine Application	Recommended Core Material
Hull Structures	PVC / SAN / PET
High-Speed Ferries	SAN / PMI
Luxury Yachts	SAN / Nomex
Naval Vessels	Nomex / PMI
Marine Ceilings	Aluminum Honeycomb
A60 Wall Panels	Aluminum Honeycomb
Interior Furniture	PP Honeycomb
Offshore Accommodation	Aluminum Honeycomb
Deck Panels	PVC / Balsa
Eco-Friendly Marine Projects	PET Foam

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12. Engineering Selection Considerations

When selecting marine core materials, naval architects and composite engineers typically evaluate:

• Density-to-strength ratio
• Fire performance
• Water resistance
• Fatigue durability
• Resin compatibility
• Manufacturing method
• Classification society requirements
• Long-term maintenance costs

Different marine sectors prioritize different performance characteristics. For example:

• Racing yachts prioritize lightweight performance
• Cruise ships prioritize fire safety
• Commercial vessels prioritize durability and cost efficiency
• Naval vessels prioritize fatigue resistance and impact tolerance