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521 Marine Grade Epoxy

521 Marine Grade Epoxy is the best solution for whatever unfloats your boat! Stronger than polyester and most adhesives, our Marine Grade epoxy boasts superior moisture, impact, and corrosion resistance and can assist in all matter of marine vessel maintenance and repair.  

$45.99 - $80.99
521 Marine Grade Epoxy
521 Marine Grade Epoxy

521 Marine Epoxy Resin bonds with fiberglass, metals, wood, and composite fabrics and features superb strength, durability, and moisture resistance. ProMarine 521 Marine Epoxy cures to a high-strength solid, suitable for laminating, bonding, fairing, coating, and reinforcing. Self-leveling properties are ideal for coating and laminating. Viscosity is favored for wetting out fiberglass cloth and other reinforcement fabrics easily. Use this versatile marine epoxy resin with 521 fast or slow hardener to complete a number of boat building, repair, and restoration projects.

  • Bonds with fiberglass, reinforcement fabrics, wood, etched aluminum, and bare steel and lead
  • Makes a strong filleting or fairing compound or adhesive 
  • Excellent thin-film characteristics provide smooth flow-out and self-leveling ideal for coating and laminating
  • Easy to measure and mix using pre-calibrated 521 Epoxy Pumps (sold seperately), or by volume
  • Easy to apply by brush, roller, syringe, spreader, or by pouring onto wood, fiberglass, reinforcement fabrics, etched aluminum, bare steel, and lead.
  • Kit comes with resin and hardener.
  • 521 Marine Epoxy Resin can be used with our 521 Fast or Slow Hardener, depending upon your application.

DIY Marine Grade Epoxy Resin Saves Money & Time

Over time, boats get “dings and dents” from use. Everyday wear-and-tear takes its toll, and boats require a bit of TLC in the form of some maintenance and repair. Marine Grade Epoxy Resin, and learning how to properly use it, can save a boat owner a great amount of time and money - taking a potentially costly endeavor – and making it into an easy and efficient task.

Why Marine Grade Epoxy Resin for Boat Repairs?

Marine vessels are frequently built using polyester resins, however when the time comes to address hull and decking maintenance and repair issues, the better solution is boat epoxy resin. 2-part marine epoxy is a stronger bonding material than polyester and most other adhesives, while at the same time boasting superior moisture, impact and corrosion resistance. Marine epoxy resin also features minimal material shrinkage - unlike polyester resin which shrinks during the curing process causing potential stress points in the substrate.

Marine-grade Epoxy Resin differs from other resins in several ways:

  • Viscosity - self-leveling thin-film formula designed for coating, laminating and reinforcing - as well as wetting out fiberglass cloth and other reinforcing fabrics surfaces (not designed for clear-coating applications as tabletop, art & casting resins are)

  • Bonding & Curing - like other epoxy resins, marine epoxy cures to a high-performance plastic solid that bonds to wood, metals, fiberglass and composite materials that features high strength, as well as superior impact, corrosion and water/moisture resistance; however, boat epoxy resin is not designed for clear-coating applications

  • Finish – cures to a light amber solid that may be sanded, shaped and painted

  • Hardener Options – marine grade epoxy resins feature two hardener options:

    • Fast Hardener – for quick repairs in cooler temperatures of 60-70 degrees F, with a working time (pot life) of 12 minutes
    • Slow Hardener – for applications requiring more working time and performed in warmer temperatures of 80 degrees F and above, with working time (pot life) of 30 minutes

Bonds To

  • Fiberglass
  • Reinforcement Fabrics
  • Wood
  • Etched Aluminum
  • Bare Steel
  • Lead
  • Granite
  • Tile


  • High-Strength Solid
  • Moisture-Resistant
  • Simple Measure & Mix
  • Self Leveling
  • Cures Amber
  • Easily Sand and Shape

Marine Grade Epoxy Versions

521 Fast Hardener

Fast Hardener is a perfect selection for applications requiring quick working time and for use in cooler climates (recommended use 60-70°F)
  • Minimum recommended temperature (Fast Hardener): 60°F - In cooler temperatures, the 521 Epoxy Resin/Fast Hardener mixture remains workable to give you adequate time for application, and it speeds up cure time.
  • The recommended temperature for use and dispensing via pump: 60-70°F
  • Pot life @ 70°F: 12 minutes (Fast Hardener)
  • Set time @ 70°F (thin film): 6 hours
  • Cure time @ 70°F (thin film): 1 to 4 days
  • Hardener Color: 521 Fast (Dark Amber)

521 Slow Hardener

Slow Hardener is a perfect selection for applications requiring more working time and for use in warmer climates (recommended use above 80F)
  • Minimum recommended temperature (Slow Hardener): 80°F - Slow Hardener buys you a little more working time in warmer temperatures that tend to reduce working time and cure time of epoxy resins.
  • The recommended temperature for use and dispensing via pump: above 80°F
  • Pot life @ 80°F: 30 minutes (Slow Hardener)
  • Set time @ 80°F (thin film): 10 hours
  • Cure time @ 80°F (thin film): 1 to 4 days
  • Hardener Color: 521 Slow (Clear-Light Amber)

Compatibility: Pro Marine Supplies 521 Epoxy Resin can be used interchangeably with 521 Fast or Slow Hardeners.

Safety Information

Always wear protective clothing and equipment to protect your eyes, skin, and lungs when working with 521 Marine Grade Epoxy Resin and Hardeners. Personal protective clothing should include appropriate gloves, safety glasses or goggles, a respirator, and protective clothing.

*Please note: The 521 Marine Epoxy is not meant for clear coating, Table Top, Counter, or Art Applications. Please see our Table Top Epoxy for those types of applications.


Printable Guide Boat & Building Repair with Marine Epoxy

Printable Data Sheet: 521 Marine Grade Epoxy

521 Marine Grade Epoxy Resin Instructions