300t Active Heave Compensated (AHC) Deep Water Lifting System
Complete Active Heave Compensated (AHC) traction winch system designed for precise deep-water deployment in up to ~3,000 m water depth.
It combines a high-capacity two-drum traction winch (320 t line pull) with a constant-tension storage winch and a hybrid Passive + Active Heave Compensation system.
Suitable as a standalone under deck winch system, crane upgrade to AHC, or deployment via A-Frame.
Overall System Specifications
| Parameter | Value / Description | Notes |
|---|---|---|
| System Type | Active Heave Compensated (AHC) Deep Water Lifting / A&R Winch | Hybrid Passive + Active |
| Rated Traction Winch Line Pull | 320 t | ~300 t SWL class |
| Maximum Deployment Depth | ~3,000 m | With 3,000 m wire rope |
| Reeving | Single fall | Via deck beam sheaves |
| Heave Compensation | Hybrid Passive main cylinder + 2× Active auxiliary cylinders (AHC) | MRU-driven, dedicated HPU + N₂ PVU |
| Wire Rope | Ø 109 mm steel wire rope × 3,000 m | Stored on storage winch |
| Storage Winch Back-Tension | 15 t Constant Tension (CT) | Provides friction on traction drums |
| Drive Type | Electric VFD (traction & storage) + Hydraulic (AHC only) | Frequency controlled |
| Primary Standards | Lloyd’s Code for Lifting Appliances in Marine Environment (2003) | Fail-safe design throughout |
Detailed Component Breakdown
1. Deck Interface & Structural Components
| Component | Key Specifications | Function / Notes |
|---|---|---|
| Swivel | 300 t SWL swivel | — |
| Load Measurement Sheaves | Load pins in high-tension and low-tension sheaves | Real-time hook load monitoring & overload protection |
| Supporting Structure | High-tensile steel frames, supports, and fairleads | Interfaces with vessel deck and below-deck winches |
2. Active Heave Compensation (AHC) Package
| Component | Key Specifications | Function / Notes |
|---|---|---|
| Main Passive Cylinder (A150) | Large hydraulic cylinder with gas (N₂) charging | Primary heave absorption |
| Active Auxiliary Cylinders (×2) | Two smaller cylinders mechanically linked to main cylinder | Active correction of residual motion |
| Medium Separator | Large piston-type accumulator | Separates hydraulic fluid from nitrogen gas |
| Pressure Vessel Unit (PVU) | Multiple N₂ pressure vessels (typically 10–11 vessels) | Gas storage and pressure management for passive mode |
| Pressure Intensifier Unit (PIU) | Gas compressor / intensifier | Charges or adjusts N₂ pressure in selected vessel sections |
| Motion Reference Unit (MRU) | High-accuracy vessel motion sensor (heave, pitch, roll, yaw) | Real-time input to AHC control system |
| Dedicated Hydraulic Power Unit (HPU) | 2× main pumps + cooling & filter pumps; located in hold | Powers active cylinders and boost functions |
| Active Manifold | Servo valves, boost valves, control valves | Precise flow control for active heave mode |
| Load Cell (Heave Sheave) | Integrated in top sheave of heave compensator | Load feedback for AHC and overload protection |
| Control Modes | Idle / Passive HC / Active HC; semi-automatic sequences available | Active mode used only during seabed landing/lift-off |
3. 300 t Traction Winch
| Component / Feature | Specification | Function / Notes |
|---|---|---|
| Configuration | Two drums (upper + lower) in common frame | High line-pull without storing wire |
| Line Pull | 320 t total | Primary hoisting / lowering force |
| Drive | 8× electric motors (4 per drum) with VFDs | Speed-controlled operation |
| Brakes | Individual disc brake per motor (fail-safe) | Dynamic + parking; engage on E-stop or power loss |
| Lubrication | Centralized pump (cyclic) + gearbox oil coolers | Continuous operation capability |
| Protection | DISPS (Drum Independent Protection System) | Independent drum monitoring & protection |
| Control | Speed mode (normal); independent drum control (service mode) | Local control cabinet available for reeving |
4. 15 t Storage Winch with Spooling Device
| Component / Feature | Specification | Function / Notes |
|---|---|---|
| Line Pull (CT Mode) | 15 t constant tension | Back-tension for traction winch friction |
| Drum Capacity | 3,000 m of Ø 109 mm wire rope | Full wire storage |
| Drive | 2× electric motors with VFDs + fail-safe disc brakes | Follows traction winch speed in CT mode |
| Spooling Device | Mechanical diamond-screw type, chain-driven from drum | Ensures proper spooling; max fleet angle ≤ 1.5° |
| Tension Monitoring | Load cell (dual-range output, e.g. 0–120 mT) | Closed-loop CT control |
| Length / Position Monitoring | Toothed sheave + proximity switches + geared limit switch | Accurate paid-out length + end-position protection |
| Rope Termination | 6× M30 8.8 bolts + clamping plate; minimum 5 safety turns always required | Secure attachment |
| Control | CT mode (normal); speed mode (service) | Local panel for reeving & maintenance |
5. Wire Rope & End Fittings
| Item | Specification | Notes |
|---|---|---|
| Wire Rope | Ø 109 mm steel wire rope | 3,000 m length |
| Working End | 300 t SWL swivel | — |
| Safety Requirement | Minimum 5 full turns on storage drum at all times | — |
6. Drive, Control & Safety Systems
| Category | Components / Features | Notes |
|---|---|---|
| Main Drives | Electric VFDs (traction & storage winches) | High reliability, precise speed control |
| Control Architecture | Dedicated winch PLC + heave PLC; SCADA/HMI | Ethernet / Profibus network |
| Operator Interface | Bridge/operator station SCADA + local control cabinets | Joystick for traction; pushbuttons for AHC |
| Safety Systems | Fail-safe design, normally-closed E-stops, DISPS, load cells, limit switches, separate “Passive Heave” E-stop circuit | Malfunction → safe state |
| Monitoring | Line pull, paid-out length, drum status, heave parameters, tensions, temperatures | Real-time display on SCADA |
| Power Supply | 440 Vac 60 Hz ship supply + 930 Vdc rails for drives | Dedicated starters and cabinets |
