Cox Marine Commissions 12m MIRANDA Diesel Outboard Test Vessel

A dedicated vessel for integrated propulsion testing

Cox Marine has commissioned a 12-metre purpose-built vessel named Miranda to support the development, validation and demonstration of its diesel outboard technology. The British manufacturer introduced the new Tideman RBC1200 at the International Workboat Show in Hoorn, Netherlands, on 29 and 30 September, before describing the project in a formal announcement dated 6 October 2026.

Miranda is more than a floating display for an engine: Cox intends to use the vessel as a working engineering platform for evaluating propulsion, steering, controls, communications and navigation as a combined system. The investment offers engineers the chance to observe interactions between components under routine and demanding operating conditions rather than considering the outboard in isolation.

A tough 12-metre hull carrying twin V8 diesels

The test boat has twin Cox Marine 300-horsepower V8 diesel outboards, providing a combined nominal propulsion rating of 600 horsepower. Its Tideman RBC1200 hull is built in high-density polyethylene, a material selected for durability, impact resistance and resistance to corrosion in hard-use maritime settings.

The vessel's enclosed wheelhouse and open working deck make it suitable for the variety of operations used in trials and customer demonstrations. Cox identifies patrol, law-enforcement, offshore support, harbour duties and search-and-rescue activity among the types of professional mission relevant to its development programme, but it has not announced Miranda as a commissioned customer vessel for any of those services.

From electronic steering to compliant navigation

Equipment aboard Miranda includes Dometic electronic steering, joystick control and autopilot functions, alongside integrated navigation and communications systems. Cox says the boat has been built around MCA Workboat Code Edition 3 requirements, with certification achieved in cooperation with MECAL and a compliant small-vessel electronic chart system included.

Integrating these components into one demonstrator matters because electronically controlled engines must cooperate with helm commands, maneuvering equipment, alarms and the vessel's navigation suite. A successful standalone engine test is not the same as validating a complete operational installation, especially where crew workload and repeatable low-speed handling are important.

Why superyacht tender operators should pay attention

Although Miranda is a professional workboat rather than a superyacht tender, its systems-development work may have relevance to the chase boats and auxiliary vessels that support larger yachts. Captains choosing propulsion for heavily used craft must consider serviceability, electronic controls and manoeuvrability alongside weight, endurance and the availability of spares.

Cox plans to employ Miranda for product testing, partner demonstrations, trials and technical training, providing a repeatable platform for new configurations. The current announcement confirms the vessel's commissioning and public debut; any claims about performance improvements in future yacht installations will need to be assessed on those installations' own evidence.