Duramax Marine

What Duramax Marine does

Duramax Marine LLC is a privately held manufacturer of marine propulsion and vessel protection equipment headquartered in Hiram, Ohio. The company designs and produces water-lubricated bearings, heat exchange systems, shaft seals, and impact protection products for military, commercial, and recreational marine markets. Its flagship Johnson Cutless bearing is the original water-lubricated rubber bearing in the industry, and the company holds proprietary material formulations spanning nitrile rubber compounds, polymer alloys (DMX), composite materials (DuraBlue), and UHMW-PE composites. Duramax products are installed on more than 90% of U.S. Navy surface ships and submarines and are certified by ABS, Lloyd's Register, RINA, DNV, Bureau Veritas, and Vietnam Maritime Administration, with bearings meeting MIL-DTL-17901C Class II specifications.

The company operates an engineering-led, quote-based business model selling custom-engineered hardware through a combination of direct phone sales staffed by product experts, a global network of stocking distributors, and regional warehouses in Ohio and Louisiana. It maintains in-house R&D capabilities including an 800,000-gallon testing facility built in 1998 for full-scale keel cooler evaluation, an accredited laboratory, and CFD-validated product development workflows. Customers include the U.S. Navy, U.S. Coast Guard, allied navies worldwide, and commercial operators such as Maritime Partners LLC with its approximately 2,000-vessel towboat and barge fleet, as well as recreational boat owners purchasing through local distributors. In November 2024, Duramax expanded its product portfolio through an asset acquisition of Morse Rubber LLC's marine bearing, dock fender, and marine bumper business from FLSmidth Group.

Duramax sells through five core product lines: Johnson Cutless rubber sleeve and flange bearings, Advanced Bearings (ROMOR I stave, DMX Polymer Alloy, Demountable Stave, and DuraBlue Composite), DuraCooler heat exchange systems (including the patent-pending SuprStak double-stacked configuration), Shaft Seal Systems (DryMax, stuffing boxes, mechanical face seals, Ultra-X packing), and Impact Protection Systems (EPDM dock bumpers, tow knees, Linerite batterboard). The company holds 10 registered trademarks, maintains ISO 9001:2015 certification audited by Smithers Quality Assessments, and competes on the basis of proprietary materials science, regulatory certifications, and an installed base that supports long-tail service revenue including bearing relining.

Name

Duramax Marine

Legal name

Duramax Marine LLC

Website

https://duramaxmarine.com

Company type

Private

Founded year

1999

Operating status

Operating

Headcount range

51–100 employees

Short description

Duramax Marine LLC manufactures water-lubricated marine bearings, heat exchangers, shaft seals, and impact protection systems for military, commercial, and recreational vessels. Its proprietary Johnson Cutless and ROMOR I bearings are installed on over 90% of U.S. Navy surface ships and submarines.

Ownership category

akta.pro rank

Product category

Marine Bearings & Vessel Propulsion Components

NAICS

Ship Building and Repairing (336611), Synthetic Rubber Manufacturing (325212)

SIC

Ball & Roller Bearings (3562), Plastic Materials, Synth Resins & Nonvulcan Elastomers (2821), Miscellaneous Plastics Products (3080)

akta.pro primary industry

Sealants, Adhesives, Gaskets & Marine Elastomers (IMAJAKAL)

akta.pro secondary industry

Deck Fittings & Hardware (Bitts, Fairleads, Cleats, Anchors & Chains) (IMAJAIAK)

Keywords

• Water-lubricated bearings
• Marine propulsion components
• Heat exchange systems
• Marine shaft seals
• Vessel impact protection

Headquarters

HQ city

Hiram

HQ country

United States

HQ region

North America

Offices3 records

Markets served

GTM type

B2B

Offering type

Hardware or Manufacturing

Cost components

Supply Chain, Operations, Personnel, Technology or R&D, Marketing or Sales

Revenue model

1. Marine Bearing Systems: Water-lubricated bearing systems including Johnson Cutless, ROMOR I, DMX, and DuraBlue products. Revenue from sleeve bearings, flange bearings, stave bearings, rudder bushings, thrust washers, shaft sleeves, and stern tube fillers. Custom engineered to customer specifications.
2. Heat Exchange Systems: Custom engineered cooling systems including DuraCooler keel coolers, SuprStak double-stacked coolers, Demountable spiral tube coolers, and BoxCooler systems. Quote-based custom design for vessel-specific cooling requirements.
3. Shaft Seal Systems: DryMax shaft seals, Johnson Heavy-Duty stuffing boxes, Ultra-X compression packing, and mechanical face seals. Hardware products with various size configurations.
4. Impact Protection Systems: Commercial dock bumpers, fenders, tow knees, pusher plates, and Linerite composite batterboard systems. EPDM rubber products with various profile configurations.

Go-to-market motion2 records

Distribution channels3 records

Marketing channels7 records

Core offering

Duramax Marine manufactures and sells proprietary water-lubricated marine bearings (Johnson Cutless rubber bearings, ROMOR I stave bearings, DMX polymer alloy, DuraBlue composite stern tube bearings), DuraCooler heat exchange systems (keel coolers with SuprStak variants, demountable spiral tube coolers, BoxCoolers), shaft seal systems (DryMax, stuffing boxes, mechanical face seals, Ultra-X packing), and impact protection systems (EPDM dock bumpers, fenders, tow knees, Linerite batterboard). Products are sold through an international distributor network and direct sales to military, commercial, and recreational marine customers, with custom engineering offered for heat exchangers and bearing systems.

Product overview

Duramax Marine is a manufacturer of marine propulsion and vessel protection products organized into five core product lines: (1) Water-Lubricated Bearings including Johnson Cutless rubber bearings (the original true cutlass bearing) and Advanced Bearing Systems (ROMOR I stave bearings in dovetail and radius-back configurations, DMX Polymer Alloy bearings, Johnson Demountable Stave bearings, and DuraBlue Composite stern tube bearings and rudder bushings); (2) Heat Exchange Systems including DuraCooler keel coolers (with SuprStak double-stacked patent-pending variant), Demountable spiral tube coolers, and BoxCooler in-hull systems; (3) Shaft Seal Systems including DryMax axial shaft seals, Johnson Heavy-Duty Air Seal stuffing boxes, mechanical face seals, and Ultra-X compression packing; (4) Impact Protection including EPDM dock bumpers/fenders in multiple series, tow knees/pusher plates, and Linerite composite batterboard; and (5) Industrial products for hydro power and vertical pump applications. The company also offers NCB shaft sleeves and stern tube filler as accessories. Founded over 100 years ago, Duramax Marine serves military, commercial, and recreational marine markets worldwide with ISO 9001:2015 certification.

Differentiator

Problem solved

Functional benefit

Brands

• Johnson Cutless: Water-lubricated rubber bearings and sleeve bearings product line; the original and only true Cutless bearing brand; used in more vessels worldwide than any other water-lubricated bearing.
• DuraBlue
• DuraCooler
• DryMax
• Ultra-X
• DMX
• ROMOR I
• Linerite

Products and services

• Johnson Cutless Water-Lubricated Bearings The original true cutlass bearing, using proprietary nitrile rubber polymer bonded into naval brass or non-metallic shells. Available as sleeve bearings and flanged bearings in shaft sizes from 3/4" to 6-1/2" for strut and stern tube applications. First and only bearing to meet all MIL-DTL-17901C Class II requirements. Used in more vessels worldwide than any other water-lubricated bearing; serves military, commercial, and recreational marine markets.
• Advanced Water-Lubricated Bearing Systems Custom-engineered high-performance water-lubricated bearing solutions including ROMOR I stave bearings (dovetail and radius-back configurations) with nitrile rubber bonded to UHMW-PE backing, DMX polymer alloy stave bearings for abrasive environments, Johnson Demountable Stave bearings allowing replacement without shaft or propeller removal, and DuraBlue composite stern tube bearings and rudder bushings. ABS, Lloyd's, RINA, DNV, and Bureau Veritas approved for various configurations.
• DuraCooler Heat Exchange Systems Custom-engineered marine heat exchange systems including the DuraCooler keel cooler (improves heat transfer more than 17% over traditional designs), DuraCooler SuprStak double-stacked keel cooler with TurboTunnel design that more than doubles heat transfer in half the hull space (patent pending), 90/10 cupronickel Demountable spiral tube keel coolers in 4 to 24 tube configurations, and Duramax BoxCooler in-hull cooling systems with Impressed Current Anti-Fouling (ICAF). Custom quote-based design for vessel-specific cooling requirements.
• Shaft Seal Systems Complete line of marine sealing systems including the DryMax water-lubricated axial shaft seal (uses no grease or oil; features DuraChrome mating ring and inflatable air seal for at-sea maintenance; ABS type approved), Johnson Heavy-Duty Air Seal stuffing boxes (bronze construction, repacking at sea without dry-docking, shaft sizes 2.5" to 36"), Duramax Mechanical Face Seal System (maintenance-free for shafts 3/4" to 6-3/4" in BRZ/FRP/Weld-On configurations), and Ultra-X high-performance PTFE compression packing (outlasts flax 5 to 1, 300% lower friction).
• Impact Protection Systems Commercial-grade impact protection for vessels and dock structures including EPDM rubber dock bumpers and fenders (ASTM D2000 specification, available in 100-2100 series profiles), rubber-to-metal bonded tow knees/pusher plates (single, double, pre-curved, and segmented models with steel or aluminum substrates), and Linerite composite batterboard systems combining thermoset elastomer/plastic with UHMW-PE facing as a replacement for wooden timbers. EPDM products can last 4X longer than SBR or butyl fenders per company claims.
• NCB Shaft Sleeves and Johnson Cutless Stern Tube Filler Accessories supporting bearing installations and stern tube maintenance: NCB Shaft Sleeves with Nickel-Chrome-Boron alloy hard coating (58-62 Rockwell C hardness, extending shaft and bearing wear life by 4-5 times) and Johnson Cutless Stern Tube Filler (environmentally-friendly water displacement medium for freeze damage protection during winter layup, available in 5-gallon size).
• Duramax Industrial Products (Hydro Power and Vertical Pump Bearings) Industrial extension of Duramax water-lubricated bearing technology serving hydro power generation and vertical pump applications, applying the same proprietary rubber and composite bearing technologies used in marine propulsion to non-marine industrial rotating equipment.

Quantifiable outcome

• More than 90% of U.S. Navy surface ships and submarines operate with Duramax water-lubricated bearing technology
• +9 more outcomes

Named customers4 records

Segments3 records

Ideal customer profiles3 records

Technology focussed No

API detail

Has API

No

API docs

API detail

Core technology

AI maturity

App detail

Feature6 records

Partnerships

One partnership is on record.

• Morse Rubber LLC (FLSmidth Group)coreStrategic or Co-development Partner · 4 November 2024Duramax Marine acquired the assets related to the marine bearing, dock fender, and marine bumper business from Morse Rubber, a member of the FLSmidth Group of companies. The transaction includes tooling, inventory, and equipment related to the marine business, moving to Duramax Marine facilities in Ohio. Neither facilities nor employees were included in the transaction.

Scale indicators6 records

Recent moves5 records

Expansion highlights6 records

Direct peers

• John Crane: Smiths Group division specializing in mechanical seals, shaft seals, and bearing systems for marine, oil & gas, and process industries. Closely comparable to Duramax's DryMax water-lubricated shaft seal and mechanical face seal product family.
• Thordon Bearings: Canadian manufacturer of water-lubricated propeller shaft bearings and stern tube bearings for marine and industrial markets. Direct head-to-head competitor to Duramax's Johnson Cutless, ROMOR, and DuraBlue product lines, serving the same commercial marine and naval newbuild/retrofit customers.
• GGB Bearing Technology: Manufacturer of polymer, composite, and self-lubricating plain bearings used in marine, hydropower, and industrial applications. Direct material-and-application overlap with Duramax's DMX polymer alloy, DuraBlue composite, and DuraChrome technologies.
• Trelleborg Marine & Infrastructure: Division of Trelleborg AB producing marine fenders, dock bumpers, and vessel impact-protection systems. Directly comparable to Duramax's EPDM dock bumpers, tow knees, and Linerite batterboard portfolio following the 2024 Morse Rubber asset acquisition.
• Miko Marine: Norway-based specialist in marine fenders, foam fenders, and vessel docking protection systems. Comparable to Duramax's impact protection business in product scope and customer base (shipyards, ports, towboat operators).

Broad incumbents

• SKF: Global rolling-element and plain bearing manufacturer serving marine, industrial, and aerospace end markets. Comparable in bearing category breadth to Duramax's water-lubricated bearings but at vastly greater scale and without Duramax's water-lubricated depth.
• GEA Group: German manufacturer of heat exchangers, separators, and marine process equipment. Comparable to Duramax's heat exchange systems business within a much larger industrial portfolio.
• Wärtsilä: Finnish broad marine systems integrator providing ship power, propulsion, and lifecycle services. Operates overlapping equipment (seals, bearings, heat exchangers) inside a much wider portfolio that includes engines and integrated solutions.
• Alfa Laval: Swedish manufacturer of marine heat exchangers, separators, and fluid handling equipment. Direct overlap with Duramax's DuraCooler keel cooler and heat exchange product line as part of a broader marine equipment portfolio.
• Trelleborg Sealing Solutions: Trelleborg division producing precision polymer and elastomer rotary seals, O-rings, and custom-molded elastomer components. Comparable to Duramax's shaft seal and Ultra-X compression packing product family in elastomer sealing science.

Market position

Strengths5 records

Weaknesses5 records

Competitive moat5 records

Key risks5 records

Key highlights6 records

Customer concentration

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Compliance21 records

Revenue estimate

Valuation estimate

Number of profiles

Profiles1 record

Funding overview

Funding rounds

Investors

Funding detail is available on the Subscription and Enterprise plan.Contact sales →

M&A

Investments

M&A and investment is available on the Subscription and Enterprise plan.Contact sales →

Frequently asked questions about Duramax Marine