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Marine Core Solutions for FRP Vessel Builders

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Core Material by Category – Where Each Type Belongs

PVC foam, PET foam, PP honeycomb and Polyimide (PI) foam each fulfill distinct structural functions in composite sandwich construction. Below is a high-level overview of their respective positioning. Please click through the links to access detailed density specifications and full application comparison tables for your reference.
Marine Grade PVC Foam Core from China Manufacturer JLON

Jloncell PVC foam core

What is PVC foam and where is it used in boat building?

PVC foam is a closed-cell structural foam widely used as the core material for FRP boat hulls, especially in planing vessels that require high fatigue resistance.

Best suited for:

Vessels where fatigue life and impact resistance matter most – planing speedboats, patrol craft, commercial work boats, and high-performance yachts.

Common applications:

Hull bottoms (primary sandwich structure)
Hull sides and chine areas
Decks and superstructures
Structural bulkheads

Why PVC foam dominates:

Proven fatigue life under cyclic wave loading. Excellent compatibility with polyester, vinyl ester, and epoxy resins. Closed-cell structure prevents water absorption. Available in densities from 45 to 300 kg/m³ – from flexible hull panels to rigid hard points.

Jloncell PET foam core

Can PET foam be used instead of PVC for boat hulls?

PET foam is a recyclable structural foam that offers excellent resistance to hydrolysis (moisture and heat aging). It is increasingly specified for displacement vessels and green-certified projects.

Best suited for:

Vessels where environmental credentials matter, or where long-term moisture resistance is critical – sailing yachts, bluewater cruisers, catamarans, and any project targeting green certification.


Common applications:

Hulls of displacement vessels (superior hydrolysis resistance)
Deck structures
Interior bulkheads (where structural contribution is needed)
Panels requiring high heat deflection temperature

Why builders choose PET foam:

Fully recyclable at end of life. Excellent resistance to hot, humid aging (hydrolysis). Good mechanical properties similar to PVC in many densities. Strong marketing value for eco-conscious yacht buyers.
PET Foam Core for Marine Composite Structures
PP-honeycomb

Jloncell PP honeycomb

Is PP honeycomb strong enough for boat floors?

PP honeycomb is an ultra-light, non-structural core material designed for interior panels. It saves 30–50% weight compared to foam of the same thickness, but it does not contribute significant shear stiffness and should never be used in hulls or structural decks.

Best suited for:

Any vessel where weight reduction and cost control matter – but the part does not carry structural load. Used across all boat types: speedboats, yachts, workboats, passenger ferries.

Common applications:

Cabin floors and sole plates
Interior walls and partitions
Ceiling panels
Locker doors and non-structural hatches


Why PP honeycomb is specified:

Extremely low density (saves 30–50% weight compared to foam of same thickness). Low cost. Easy to bond with decorative skins (wood veneer, laminate, carpet).

Jloncell Polyimide Foam

What is polyimide foam used for in marine applications?

Polyimide foam is a high-performance, non-flammable foam designed for thermal and acoustic insulation. Unlike PVC or PET, it does not melt or drip flames and remains stable from -196°C to +300°C.

Important:

Polyimide foam is for insulation, not for structural sandwich hulls. If you are building a standard FRP hull, PVC or PET is the correct choice.


Best suited for:

Vessels where fire safety, thermal insulation, and noise reduction are critical.


Common applications:

HEngine room bulkheads and exhaust trunks for naval ships and icebreakers
Acoustic insulation for diesel engines of luxury yachts
Thermal insulation for LNG carriers


Why polyimide foam is specified in marine:

Non-flammable
Low smoke generation
Thermally stable
Excellent acoustic damping

Not recommended for:

Standard FRP hull sandwich structures – over-specification and too expensive where PVC or PET suffices.
Polyimide-Foam
Content-2x

Need a specific recommendation for your vessel?

We help you use them correctly – from hull sandwich panels to high-density hard points for engine mounts, winch bases, and fittings.

How to Select Core Materials by Vessel Type & Location

Vessel TypeCore RecommendationKey Considerations
Planing SpeedboatPVC hull + PP interiorHard points require 160–200 kg/m³ high-density PVC
Luxury YachtPVC or PET hull + PET deck + PP interiorPET preferred for green / eco-certified projects
Sailing Yacht (displacement)PET full hull + PP interiorPET is best for warm, humid environments
Commercial WorkboatPVC hull + PP interiorRepairability is the priority
Passenger Ferry (IMO regulated)Fire-rated PVC/PET + fire-rated PPIMO certification required
Warships, Icebreakers, LNG CarriersPolyimide foam for insulation; PVC/PET for structural areasFire safety, acoustic damping, thermal from -196°C to +300°C

Frequently Asked Questions

  • What core material should I use for a planing speedboat hull?

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    For a planing speedboat hull (25+ knots), PVC foam is the standard choice because it offers the best fatigue life under repeated wave impact.


    PVC foam guide →

  • Can I use PET foam instead of PVC for a yacht hull?

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    Yes, PET foam can replace PVC for many yacht hulls, especially for displacement or semi-displacement vessels in warm climates where moisture resistance matters.

  • Why do my deck fittings keep loosening?

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    You are bolting into low-density foam without a hard point. The foam crushes under load. The solution is to install high-density PVC foam (130–300 kg/m³) at every bolt location.

  • Is PP honeycomb strong enough for boat floors?

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    Yes, for non-structural interior floors and walls. PP honeycomb is ultra-light, rot-proof, and cost-effective. Do not use it in hulls or structural decks.


    PP honeycomb guide →

  • What density PVC foam for a boat hull?

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    For planing hulls, 80–100 kg/m³. For yacht hulls, 60–80 kg/m³. For hard points (engine mounts, cleats), 130–300 kg/m³.

  • When do I need fire-rated marine cores?

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    When your vessel carries passengers for hire, or when IMO, SOLAS, or local passenger vessel regulations apply. Standard PVC or PET foam will not pass.

  • Do you supply DNV certified foam?

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    Yes. We supply DNV certified grades on selected PVC and PET foams.

Related Products – Complete Composite Solutions

Boat builders also source these products from us:
VACUUM-infusion-consumables

Vacuum Infusion Consumables

Bagging film, flow media, peel ply, tubing

Fiberglass-Fabrics

Fiberglass Fabrics

For hull and deck reinforcement

High-Performance-Fibers

Carbon Fiber Fabrics

For hull and deck reinforcement

Epoxy-&-Polyester-Resins

Epoxy & Polyester Resins

Compatible with all our core materials