Rotterdamsche Droogdok Maatschappij (RDM)

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Submarine

Netherlands

Rotterdamsche Droogdok Maatschappij (RDM)

Walrus class

The Royal Netherlands Navy's diesel-electric attack submarine class, known for its distinctive X-form stern rudders and quiet operation in the shallow, congested waters of the North Sea and Baltic approaches. Due to be replaced by new-build submarines under the Dutch Walrus Replacement Program, selecting the French Naval Group Barracuda design.

In service since 1990 · 1 operator countries

Compiled from public sources ·primary reference ↗ ·last verified 2026-07-02

300

m depth

1,900

crew

Pricing: Unit cost not publicly disclosed

Procurement snapshot

Availability & export

National export licensing

Subject to Netherlands export-control approval; verify eligibility with the manufacturer.

Channel: Direct commercial / G2G

Fielded & proven

Limited · 1 operator

In service since 1990. Status: active · ~4 built.

Lifecycle cost (est.)

No public unit price to model from.

Interoperability

No standardised NATO calibre / datalink detected in public specs.

Derived guidance from public data — export regime by country of origin, lifecycle from the GAO ~30% acquisition rule. Verify eligibility, pricing and offsets with the manufacturer and your acquisition authority.

Full specifications

Firepower

Armament, payload and guidance.

Torpedo tubes Number of torpedo tubes (submarines and some surface ships).: 4

Stronger than 13% of submarines

Physical

Dimensions, weight and crew.

Length Overall length including gun/probe where applicable.: 67.73 m

Naval

Displacement, speed, endurance and diving depth.

Displacement Standard displacement in tonnes — the ship’s size class. Larger hulls carry more but cost more and are less agile.: 1,900 t
Submerged speed Maximum speed while submerged (submarines). Higher is faster underwater.: 21 kn

Stronger than 53% of submarines
Test depth Maximum rated diving depth (submarines). Deeper is harder to detect and engage. Actual crush depth is classified.: 300 m

Stronger than 55% of submarines
Complement Crew size. Fewer eases manning cost; more may indicate a larger, more capable platform.: 50
Propulsion plant Machinery type — nuclear reactor, gas turbine (COGAG), CODAG, diesel-electric, AIP.: Diesel-electric

Program

Cost, production scale and operators.

Units built Total production run. Higher means proven manufacturing, mature logistics and spares availability.: 4

Stronger than 39% of submarines
Operator countries Number of countries operating the system. More operators means broader support ecosystem.: 1

Stronger than 39% of submarines

Specifications compiled from public Rotterdamsche Droogdok Maatschappij (RDM) and reference sources ↗. Published defense figures are approximations — treat comparisons as directional. Last verified 2026-07-02.

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Frequently asked questions

What is the Rotterdamsche Droogdok Maatschappij (RDM) Walrus class used for? +

The Rotterdamsche Droogdok Maatschappij (RDM) Walrus class is a submarine typically used for isr.

How many countries operate the Rotterdamsche Droogdok Maatschappij (RDM) Walrus class? +

The Rotterdamsche Droogdok Maatschappij (RDM) Walrus class is operated by 1 countries.

How much does the Rotterdamsche Droogdok Maatschappij (RDM) Walrus class cost? +

Rotterdamsche Droogdok Maatschappij (RDM) Walrus class: Unit cost not publicly disclosed. Defense program costs are rarely fully public and vary by contract and configuration.