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Product

MV subsea trencher & plough umbilicalISO 13628-53.3–6.6 kV MV400–2,500 HP

Subsea Trencher Umbilical3.3–6.6 kV high-power dynamic electro-optical umbilical for seabed trenchers & ploughs

Medium-voltage dynamic subsea umbilical delivering 400–2,500 HP (3.3 kV, 4.16 kV or 6.6 kV) power plus 316L FIMT optical telemetry to seabed jetting trenchers, mechanical cutters, pipeline ploughs and subsea mining crawlers.

Water-resistant
Anti-torsion braid
EMC screen
Oil-resistant
Order designation
STU-LIFT-66-3X35-24FO
Nominal OD
51.0 mm
Weight in sea
4,610 kg/km
Safe working load
135 kN
Breaking load
675 kN
All sizes (12)
Request a quoteDatasheetWhatsApp
Engineering reply in 2 business hoursCut-to-length export drumsEN 10204 3.1 certificate per drum
Voltage grade
3.3–6.6 kV
MV power for 400–2,500 HP trenchers
Power cores
3 × 16–95 mm²
Compacted Class 5 tinned copper
Optical unit
12–24 SM/MM
Dual redundant 316L FIMT tubes
Breaking load
150–900 kN
Steel lift armour or polyaramid catenary
Design depth
Up to 3,000 m
Hydrostatic water-blocked MV matrix
Min. bend R
12–15 × OD
Dynamic LARS sheave & stern chute

Typical values for this cable type, based on ISO 13628-5 / IEC 60502-2 / DNV-ST-E402 — confirmed in the datasheet and quotation for your order.

Application fit

Is Subsea Trencher Umbilical right for your machine?

Available in contra-helically steel-armoured top-tensioned lift designs or polyaramid-braided float-over catenary designs for tracked seabed vehicles.

Immersion & wet locations

Suitable

Water-tree-retardant HEPR/XLPE MV insulation and hermetic 316L FIMT withstand continuous deepwater operation.

Vertical / spreader reel

Suitable

Contra-helical GIPS armoured variants (STU-LIFT) support combined vehicle + umbilical weight during launch and recovery.

Trailing & towing

Suitable

Polyaramid-reinforced catenary variants (STU-CAT) pair with buoyancy modules to decouple vessel heave from tracked crawlers.

Offshore platform & shipboard deck trays

Suitable

Heavy-wall HDPE or polyether PUR outer sheath resists stern-roller and seabed boulder abrasion.

Energy chain / drag chain

Not suitable

Large-diameter MV subsea trencher umbilical is not intended for indoor machine cable carriers.

Use NTSCGEWÖU MV Reeling
Typical machinesOffshore Wind Export & Array BurialSubsea Pipeline Jetting & PloughingMechanical Rock & Clay TrenchingSubsea Telecom Cable BurialDeep-Sea Polymetallic Mining

Construction

Layer by layer

Representative 6.6 kV trencher umbilical: 3×35 mm² MV screened power cores + 2 interstitial earth cores + 1×24FO 316L FIMT + inner PE bedding + double armour + outer jacket.

123456
Schematic, not to scale — generated from the layer data
#LayerMaterial & reference
1MV phase & auxiliary conductorsCompacted circular stranded tinned copper (IEC 60228 Class 5), 3 × 16 mm² to 3 × 95 mm² main MV power + optional 0.6/1 kV auxiliary triadsDelivers up to 2.5 MW to subsea water-jet pumps and cutter motors
2Triple-extruded stress controlExtruded semiconductive conductor screen and strippable semiconductive insulation screenEliminates partial discharge at 3.3 kV, 4.16 kV and 6.6 kV operating stresses
3WTR-HEPR / XLPE MV dielectricWater-tree-retardant high-modulus EPR (HEPR) or XLPE insulation to IEC 60502-2Maintains dielectric integrity under wet hydrostatic cycling
4Metallic phase & interstitial earthsTinned copper wire + tape screen on each MV core plus interstitial split protective earth conductorsProvides symmetrical fault-current return path and EMC screening
5Redundant 316L FIMT optical units1 or 2 laser-welded 316L stainless-steel tubes containing 12–24 ITU-T G.652.D / G.657.A1 fibresCarries real-time sonar, gyro, plough tow-force and HD video telemetry
6Contra-helical steel or polyaramid armourDouble contra-helical GIPS steel wire armour (lift umbilical) or high-modulus polyaramid braid (buoyant catenary umbilical) under an extruded HDPE/PUR jacketWithstands up to 900 kN breaking load and stern-chute bending

STU-LIFT (Steel-Armoured Lift Umbilical)

Double contra-helical GIPS steel wire armour for combined power/telemetry and mechanical launch/recovery or plough towing

STU-CAT (Polyaramid Catenary Umbilical)

Lightweight polyaramid-braided PUR-jacketed dynamic umbilical deployed with clamp-on syntactic floats for tracked jetting trenchers

Technical data

Ratings & operating limits

Typical values: Typical values for this cable type, based on ISO 13628-5 / IEC 60502-2 / DNV-ST-E402. Values for your order are confirmed in the datasheet and quotation.

Electrical

Rated MV voltage (U0/U)
1.8/3 (3.6) kV · 2.4/4.16 kV · 3.8/6.6 (7.2) kV
Auxiliary control voltage
0.6/1 (1.2) kV AC
AC routine test voltage
6.5 kV AC (3.3 kV) / 11.0 kV AC (6.6 kV) for 5 min
Partial discharge level
≤ 5 pC at 1.73 × U0
Max. conductor temperature
+90 °C continuous · +250 °C short-circuit

Thermal

Subsea operating temperature
−10 °C to +60 °C
Deck winch operation
−25 °C to +75 °C
Thermal dissipation
Derate ampacity for multi-layer deck winch turns

Mechanical

Design water depth
Up to 3,000 m
Min. breaking load (STU-CAT)
150 kN to 320 kN (polyaramid)
Min. breaking load (STU-LIFT)
350 kN to 900 kN (contra-helical GIPS)
Min. bend radius (dynamic)
12 × OD (STU-CAT) · 15 × OD (STU-LIFT)
Torsional balance
≤ ±2°/m under working tension

Optical

Optical fibre spec
ITU-T G.652.D / G.657.A1 SM & OM3 MM
Fibre count
12, 18 or 24 fibres (single or dual FIMT)
Attenuation (1310 / 1550 nm)
≤ 0.36 dB/km / ≤ 0.22 dB/km

Resistance

Longitudinal water blocking
Void-free elastomeric core matrix & sealed FIMT
Seabed boulder abrasion
Heavy-wall polyether PUR or HDPE outer sheath
Oil & hydraulic fluid
IEC 60811-404 resistant

Reference standards

Subsea umbilical standard
ISO 13628-5 / API Spec 17E
MV power insulation
IEC 60502-2 / IEC 60092-354
Offshore handling rules
DNV-ST-E402

Identification

Outer jacket colour
Black with yellow stripe or High-Visibility Yellow
Phase identification
Printed phase 1, 2, 3 + green-yellow earths
Customs tariff (HS)
8544.60 / 8544.70

Sizes

12 standard 3.3 kV & 6.6 kV subsea trencher umbilical configurations

Covers polyaramid catenary float-over umbilicals (STU-CAT) and steel-armoured lift/tow umbilicals (STU-LIFT).

Dimensions, weights & breaking loads
Order designationMV Power + Aux + OpticalVoltage
kV		Nominal OD
mm		Weight in air
kg/km		Weight in sea
kg/km		SWL
kN		MBL
kN		Min. sheave R
mm		Enquiry
Polyaramid Catenary Trencher Umbilicals (STU-CAT, 3.3–6.6 kV)
STU-CAT-33-3X16-12FO3×16 + 2G10 + 3×2.5 + 12FO (Polyaramid)3.336.51,68059035150548
STU-CAT-33-3X25-18FO3×25 + 2G16 + 3×4.0 + 18FO (Polyaramid)3.340.82,19083045190612
STU-CAT-33-3X35-24FO3×35 + 2G16 + 3×4.0 + 24FO (Polyaramid)3.344.52,6801,06055230668
STU-CAT-66-3X25-24FO3×25 + 2G16 + 3×4.0 + 24FO (Polyaramid)6.645.22,64098055230678
STU-CAT-66-3X35-24FO3×35 + 2G16 + 3×6.0 + 24FO (Polyaramid)6.649.03,1801,24065270735
STU-CAT-66-3X50-24FO3×50 + 2G25 + 3×6.0 + 24FO (Polyaramid)6.653.63,9201,59075320804
Contra-Helical Steel-Armoured Trencher Lift Umbilicals (STU-LIFT, 3.3–6.6 kV)
STU-LIFT-33-3X25-18FO3×25 + 2G16 + 3×4.0 + 18FO (Steel Armour)3.342.54,4803,29095475638
STU-LIFT-33-3X35-24FO3×35 + 2G16 + 3×4.0 + 24FO (Steel Armour)3.346.85,5604,120120600702
STU-LIFT-33-3X50-24FO3×50 + 2G25 + 3×6.0 + 24FO (Steel Armour)3.351.46,8405,090145725771
STU-LIFT-66-3X35-24FO3×35 + 2G16 + 3×6.0 + 24FO (Steel Armour)6.651.06,2804,610135675765
STU-LIFT-66-3X50-24FO3×50 + 2G25 + 3×6.0 + 24FO (Steel Armour)6.655.87,6905,680160800837
STU-LIFT-66-3X70-24FO3×70 + 2G35 + 3×10 + 24FO (Steel Armour)6.661.29,3506,980180900918
  • Typical values for this cable type; dimensions and weights for your order are confirmed in the quotation.
  • Ampacity in seawater ranges from 115 A (16 mm²) to 310 A (70 mm²); apply derating factors for wound layers remaining on the deck storage drum.

Quality & approvals

Testing & inspection

Routine tests on every production length, sample and type tests per batch — documented on an EN 10204 3.1 inspection certificate.

  1. ConductorClass 5 stranding
  2. Spark test100 % in-line
  3. Lay-upCores, earth, fillers
  4. SheathingInner, braid / screen, outer
  5. Electrical testsAC voltage, resistance
  6. DimensionsOD, wall thickness
  7. Inspection documents & dispatchDrum & dispatch
Testing & inspectionTest value / referenceFrequency
Routine tests
MV AC dielectric & partial discharge test6.5 / 11.0 kV AC for 5 min + PD ≤ 5 pC at 1.73 × U0100 % of manufactured length
Bidirectional OTDR optical attenuation check≤ 0.36 dB/km @ 1310 nm & ≤ 0.22 dB/km @ 1550 nmEvery fibre in primary & spare FIMT
Sample tests
Cyclic bending over sheave (CBOS) under tensionFull load sheave cycling with post-test PD & HV verificationQualification sample
Full-scale tensile break & torque-balance testConfirm rated MBL (150–900 kN) and ≤ ±2°/m twistType approval

Inspection certificate

Issued with every drum, listing the routine test results for that length.

Product approvals

ISO 13628-5 / API Spec 17E CompliantIEC 60502-2 Medium-Voltage Dielectric Certified

Company certificates

ISO 9001ISO 14001ISO 45001VDE marks approvalUL / cULCE · LVD / EMC

Marking & supply

Ordering & delivery

Sheath marking

TEBAOFLEX STU SUBSEA TRENCHER UMBILICAL 3.3/6.6kV ISO 13628-5 [MBL kN] [METRE]
Delivery form
Heavy-duty motorised spooling reels
Standard lengths
500 m to 3,500 m continuous lengths
Accessories
Chinese fingers, bend stiffeners, buoyancy clamp guides & MV termination kits
Lead time
8–12 weeks ex-works

Technical documents

Downloads

PDFSubsea Trencher Umbilical – technical datasheet12 sizes · construction, technical data, approvalsXLSXSubsea Trencher Umbilical spec data (Excel)All 12 sizes with dimensions and data, for your BOM or quotation
Revision
2026-10-20
Updated
2026-10-20

FAQ

Questions engineers ask first

Not covered here? Send your drawing — an engineer replies within 2 business hours.

When do subsea trenchers use a polyaramid catenary umbilical (STU-CAT) versus a steel-armoured lift umbilical (STU-LIFT)?
Tracked jetting and mechanical cutter trenchers that are lifted into the water by a separate crane/A-frame wire rope often use a lightweight polyaramid-braided STU-CAT umbilical fitted with syntactic floats in an S-wave catenary. Ploughs and self-lifted trenchers that use the umbilical or LARS winch for vertical recovery use the steel-armoured STU-LIFT design.
Why are dual 316L stainless-steel FIMT optical units recommended on trencher umbilicals?
Seabed trenching subjects the umbilical to intense vibration, stern-chute bending, and high currents. Laying two independent laser-welded 316L FIMTs in separate interstices provides 100 % physical optical path redundancy so a campaign is never halted by a single fibre fault.
How is partial discharge prevented in the 3.3 kV and 6.6 kV power cores?
Each medium-voltage phase conductor is manufactured on a triple-extrusion line with a smooth semiconductive conductor screen, water-tree-retardant HEPR or XLPE insulation, and a strippable semiconductive insulation screen, Routine tested to ≤ 5 pC at 1.73 × U0 per IEC 60502-2.
How do we manage heat build-up on the deck winch drum during shallow-water trenching?
When trenching in 20–100 m water depth for offshore wind farms, most of the umbilical remains wound on the deck drum in air while only the paid-out catenary is cooled by seawater. Our engineers calculate the exact drum-layer ampacity derating or size the copper cross-section for continuous shallow-water duty.

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