Wheeled Horizontal Lay System (WHLS)

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Deployed by 1 company

Versatile system to facilitate the deployment and recovery of flexible products.

Page last modified
April 11 2024

The Wheeled Horizontal Lay System (WHLS) by Maritime Developments is an innovative, portable solution designed to facilitate the recovery of flexible products, including cables, subsea umbilicals, risers and flowlines at heavier loads from deeper waters. 

Based on MDL's portable Horizontal Lay System (HLS) design - already proven as a compact package for safe and efficient recovery of SURF with buoyancy modules - the innovation comes from the application of a wheel mechanism which results in low-friction handling: allowing for the system's pulling forces to match the deployment capability offered by the tensioner.

By incorporating a wheel into the design, the HLS' recovery capacity increases without additional space requirements or weight from additional steel structures. The 2-point contact on the product results in reduced MBR requirements, opening up the product outer diameter (OD) window for wider application.

The system consists of a range of features facilitating recovery of various lengths and diameters of products, including: an integrated hang-off for handling end fittings; davits for overhead handling of products; integrated work platform for over the side or moonpool works and an adjustable wheel position to accommodate various product diameters.

The WHLS keeps true to the base HLS design, as the complete package is portable, compact, applicable on vessels of opportunity - in summary, a cost-effective way to kit-out a locally-available vessel to handle high loads and tackle recovery projects.

Thanks to its road transportability, the WHLS can be assembled on the quayside and easily mobilised on board the vessel with a single lift, followed by a second lift for the tensioner. The system can be employed with any readily available low-cost vessel worldwide, instantly transforming it into a dedicated flex lay or retrieval solution for the duration of the project. Utilising a locally available, smaller tonnage vessel not only enhances cost-effectiveness but also reduces the project's carbon footprint, contributing to environmental sustainability. 

One of the key advantages of all MDL equipment is its capability to convert a bare back deck into a flexible handling solution. This feature proves invaluable on decommissioning scopes, where budgets are significantly more constrained due to the end of a field's life or of the associated equipment. By addressing this challenge, the WHLS enables operators to deliver on their decommissioning obligations without the high cost of deploying specialist pipe handling vessels.   

With over 20+ years track record in innovative design and manufacture of lifting and pulling equipment for the marine markets, MDL is an expert in delivering bespoke equipment that works straight out of the box. The technology is developed fully in-house, including intuitive control systems that allow safe integration of systems for efficient operations. 

Pros & Limitations
Road-transportable for most efficient transit to mobilisation port
Fully integrated – Plug & Play – negating idle, non-productive time
Versatile – modifiable with range of MDL tensioner systems (line pull / squeeze requirements and top chutes (MBR))
Modular – can be assembled on quayside off critical path before vessel arrival 
Single lift mobilisation on board with the vessel’s crane (+ second lift for the tensioner) 
Compact and adaptable to project requirements – can be mobilised on vessel stern, side or over moon pool
Accessible – all operational areas are accessible by stairs, walkway and platforms complete with handrails
Safest offshore product handling thanks to MDL tensioner technology with Failsafe Grip
Integrated hang-off system for buoyancy installation ad removal
Integrated pad basket storage located beside the tensioner to provide access for safe and efficient tensioner pad change out when offshore
E-stops mounted at each end of the HLS base frame allowing for safe control of operations
Specification Title Specification Description
Lay Spread Type
Horizontal Lay System
Max Product Tension
100Te (dynamic load)
Design Life
25 years
Design Temperature
Operational: -10ºC to +50ºC; Survival: -20ºC to +65ºC
Min Pipe Diameter
90mm OD
Max Pipe Diameter
400mm OD
Overboarding Chute Radius/Capacity
Inboard Roller Capacity
Hydraulic Davit Beams Capacity
90º coverage/5Te manual beam trolleys
Hang Off Capacity
100Te SWL
A&R Capacity
100Te SWL
WHLS Geometry Dimensions (approx. depending on configuration)
18.9m x 9.6m x 11.6m (LxBxH); 18.9m x 12.6m x 11.6m (LxBxH) (Work Platform Extended)
Weight (excl. Tensioner)
112 Te
Clearance between davits and work table
Clearance between davits and hang off
Lifting Equipment
All items supplied with dedicated lift points and lift rigging. Optional spares/workshop container can be supplied. 
Power Requirements (HLS only)
3 phase, 440V (+earth), 60Hz, 140 amp supply, 55kW HPU required
Design Appraisal
Design appraised in accordance with DNV standards
Assumed Conditions
Humidity: up to 100%; Atmosphere: marine / high salinity


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We are the creative knowledge behind market-leading equipment and engineering. Our mission Is to be the global leader in the delivery of alternative engineering solutions, which are inspired by creativity, driven by people and add value by solving challenges faced by our clients. We will solve your engineering challenges, delivering quality and value with the creative and flexible thinking that anticipates your business needs.

We have been driven this way since 1999. An independent company, MDL offers the perfect mix of track record, technical prowess, global delivery and flexibility. This makes us your trusted partner in providing integrated energy services: from port facilities and ops; through SURF, cable and mooring installations, to equipment life extension and decommissioning. 

Our tailored approach targets the most efficient execution, minimising idle days, POB and port calls. We work closely with clients to help them find the perfect package for every challenge: from the safest, most reliable and highest quality equipment, to the most experienced people in the business - including engineering experts for efficient project planning and execution.

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