VESSEL REVIEW | Purus Apache & Purus Phantom – Catamaran daughtercraft/crewboats for European windfarm support duties

UK marine services provider Purus has added the catamaran daughtercraft Purus Apache and Purus Phantom to its offshore wind support fleet.

Designed by Chartwell Marine and built by Diverse Marine through a Vard project, the craft can carry technicians from larger commissioning service operation vessels (CSOVs) to offshore inspection and maintenance assignments.

Diverse Marine announced Purus Phantom’s handover on May 19, 2026, and reported that it joined the CSOV Purus Coriolis for the first time on June 15. The first craft, Purus Apache, had been installed aboard Purus Chinook by May 26, 2025.

Diverse Marine also markets the underlying design for nearshore crew transfer duties, giving it an operating role beyond deployment from a mothership.

Low-emission propulsion coupled with comfort-enhancing features

Diverse Marine’s published design specification listed each aluminium daughtercraft as having an overall length of 12.2 metres (40 feet) and a hull length of 12 metres (39 feet). Overall beam is 4.1 metres (13 feet) while depth amidships is only 1.3 metres (4.3 feet).

The specified lightship displacement is 12.1 tonnes, rising to a maximum laden displacement of 15 tonnes. Maximum draught is listed as 0.8 metre (2.6 feet).

The vessels’ launch and recovery are done using a single-point lifting arrangement, with a Henriksen HMKRHB-15 hook included in the lifting specification.

Diverse Marine said the hull was assessed using CFD analysis and scale model tank testing. The design incorporates a high bow and low propulsor arrangement intended to support access at transfer points, together with motion dampening features intended to improve passenger comfort underway.

The vessel-specific announcements identified twin Volvo Penta D6-IPS500 engines on both Purus Apache and Purus Phantom. Diverse Marine said the installations comply with IMO Tier III NOx emissions requirements.

The Chartwell design specification listed a service speed of 23 knots and a sprint speed of 28 knots. Diverse Marine also identified low passenger saloon noise as a benefit of the IPS installation, alongside the hull’s motion dampening provisions.

The inboard propulsion arrangement is paired with exhaust aftertreatment. The design’s tank specification meanwhile provides 0.85 cubic metre (187 gallons) of MGO capacity and 0.1 cubic metre (22 gallons) of urea capacity. Freshwater and blackwater capacities are also each 0.1 cubic metre.

Although the wider design is offered with alternative propulsion arrangements and optional hybrid solutions, the announcements for the Purus sistercraft identify the twin D6-IPS500 fit.

The published seating arrangement provides 12 Grammer suspension passenger seats and two crew seats.

Air conditioning and reverse-cycle heating are included in the accommodation specification, together with heads and an emergency shower. The enclosed saloon provides the passenger space for transit, while the working deck accommodates personnel movements and equipment needed for turbine inspection or maintenance.

Protected steps connect the saloon to the flush main deck. The working deck itself is stepless, and deck equipment is mounted beneath it to reduce trip hazards. Stowage for kit bags and maintenance components is accessible through hatches that sit flush with the deck and are assisted by struts, keeping those items out of the transfer route.

At the bow, the design specifies a full-beam Buoyant Works cupped fender. Diverse Marine said the fender configuration is intended to provide grip during transfers.

Full electronics suite optimised for offshore operations

The design specification provides 24 V DC and 230 V, 50 Hz AC electrical systems, supported by a Fischer Panda 5000i generator rated at five kVA. Anchoring equipment comprises a 25kg delta-type anchor and a Maxwell HRC10-10 anchor winch.

The navigation package includes a Raymarine Axiom 12 multi-function display paired with an 18-inch radar. A Raymarine AIS and DGPS are also specified. A Furuno NX900 Navtex receiver and an LH-5000 loudhailer meanwhile support onboard communications.

An Iridium LT3100S satellite telephone provides GMDSS communications. The specified camera installation comprises four IP67-rated high-definition CCTV cameras with a network video recorder, providing coverage alongside the helm’s navigation equipment.