Conversion Candidate · Cable Repair Conversion

SX124

SW Columbus — Ulstein SX124 X-BOW · Turnkey Conversion to Fibre-Optic Repair & Maintenance Vessel

Design Ulstein SX124 · X-BOW Built 2009 · Barreras, Spain

A 2009-built Ulstein SX124, converted to a dedicated fibre-optic cable repair ship as a turnkey project delivered by Dimension through partner shipyards, with leading vendor support across the cable-handling spread. Removing the existing mission equipment releases ≈900 t of lightweight and hands over spaces already shaped for cable work — ≈1,550 t of cable in a below-deck tank, with the complete fibre-optic mission spread supplied new.

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Vessel NameSW Columbus

IMO9452945

Keel Laid2007

ClassificationDNV ✠1A1 BWM(T) Clean COMF(V-3) E0 HELDK Ice(C) NAUT(AW) SF TMON

Teal-flagged items in the specification below denote new or modified equipment within the conversion scope.

Market Context

A Repair Ship the Market Is Short Of

Around 64% of the global cable maintenance fleet reaches end of service life by 2040 against a 48% growth in cable kilometres, and most of the replacement demand sits in Asia. A converted SX124 answers that demand at a fraction of newbuild cost and lead time.

A proven X-BOW hull, already built — second-hand acquisition and conversion well below newbuild cost, with delivery in months against multi-year newbuild lead times.
A complete handling & burial spread — 40 t drum cable engine, SMD QT600 burial ROV to 2,500 msw, twin Ø3.0 m stern sheaves, 30 t quadrant and 60 t A&R winch.
Turnkey delivery, backed by leading vendors — engineering, partner-shipyard execution and vendor-supplied cable tank, ROV and jointing spread as one scope of supply.

The Conversion

Retained & New

Dimension delivers this as a turnkey conversion — engineered in-house and executed through partner shipyards, with leading vendor support across the ROV, jointing and cable-handling spread. The existing mission equipment comes out, releasing around 900 t of lightweight back to cable payload. The main hold becomes a Ø14 m below-deck cable tank, with the compressor room reworked as the cable machinery space and dedicated cable test, termination and climate-controlled jointing areas built into the existing layout.

RRetained — Hull, main machinery, generators, accommodation, ballast and anti-roll systems.
NNew (≈1,260 t) — Cable tank, cable machinery and spread, jointing shelter, ROV and LARS, stern thruster, DP2, ESS.
TTimeline — 12–14 months, subject to equipment lead times.

Technical Details

Principal Particulars

Principal Particulars
Design	Ulstein SX124 · X-BOW
Built	2009 · Barreras, Spain
Length overall	89 m
Length b.p.	82 m
Beam, moulded	19.0 m
Depth	8.0 m
Max draught	6.6 m
Lightship	≈3,760 t
Deadweight	≈3,780 t
Cable Capacity — Converted
Cable tank, below deck	≈1,650 t · Ø14 m
FOC per load-out	≈2,050 – 2,550 route-km
Stowage form	Below-deck cable tank
Power & Propulsion
Main generators	6 × Wärtsilä 9L20 @ 1,800 kW
Total installed power	≈10,800 kW
Propulsion	2 × 3,000 kW, twin CPP Ø3.6 m
Bow thruster	1,200 kW tunnel
Retractable azimuth	850 kW
Stern thruster	1,200 kW — new
Energy storage	1,500 kWh ESS — new
Emergency generator	185 ekW
Performance, Accommodation & Class
Max / economy speed	15.5 / 10.5 kn
Endurance	40 days at sea
Fuel / fresh water	1,510 / 770 m³
Continuous bollard pull	88 t
Dynamic positioning	DP2 — retrofit
Persons on board	69
Classification	DNV · Ice(C) · NAUT(AW)

All-New FO Cable Handling Spread

Burial ROV · DOHB · Stern Sheaves · Work-Class ROV

Cable Handling & Deck — All New
Lay & burial ROV	SMD QT600
Burial depth	3.0 m · 2,500 msw
Burial ROV power	450 kW
Burial ROV LARS	A-frame + umbilical winch
Drum cable engine	SMD, Ø4.0 m, 40 t
DOHB	4 wheel-pair, 4 t
Stern sheaves	2 × Ø3.0 m
Firing line	≈45 m to stern sheaves
Quadrant	1 × 30 t SWL
Work-class ROV	2,000 m rated, with LARS
Offshore crane	10 t @ 20 m retained
Grapnel & A&R winch	60 t

SX124

A Repair Ship the Market Is Short Of

Principal Particulars

Burial ROV · DOHB · Stern Sheaves · Work-Class ROV

Other Hulls Under Review

Interested in the SX124 conversion?

SX124

A Repair Ship the Market Is Short Of

Principal Particulars

Burial ROV · DOHB · Stern Sheaves · Work-Class ROV

Other Hulls Under Review

SX134

ST321

ST327

Interested in the SX124 conversion?