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SMP LTD - Commercial Diving Equipment & Hyperbaric Chambers

Wet Bell LARS and HPU

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Wet Bell LARS and HPU

The SMP Wet Bell Launch and Recovery System is designed within a compact operating footprint to minimise the required operational deck space on board a vessel or barge.  

Wet Bell LARS and HPU

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Wet Bell LARS and HPU
Wet Bell LARS and HPU
Wet Bell LARS and HPU
Wet Bell LARS and HPU
Wet Bell LARS and HPU
Wet Bell LARS and HPU
Wet Bell LARS and HPU
Ref: LAR-WB-3
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The SMP Wet Bell Launch And Recovery System is designed within a compact operating footprint to minimise the required operational deck space on board a vessel or barge.  Emphasis has been placed on ease of mobilisation and demobilisation, so that costs are kept to a minimum.  The Wet Bell LARS is IMCA D023 and D018 compliant and has Third Party Design approval to Lloyds Rules for Lifting Appliances in a Marine Environment.

When fully retracted by the hydraulic cylinders, with the wet bell and clump weight stowed on the heavy duty based skid, the size and dimensions of the Wet Bell System are exactly the same size width as an ISO 20’ container and shorter in the base length by approx 1.8 mtrs.  The heavy duty based skid has ISO corner castings situated on each corner so that the system can be located on conventional transport or container ship for shipment with no out of gauge additional costs applicable.

The main components and features of the Wet Bell System are as indicated below:-

  • Heavy Duty Base Skid with Elevated Winch Platform
  • Heavy Duty “A” Frame
  • The “A” Frame pivot points and sheaves incorporate Stainless Steel Pins with Grease Nipples
  • Two “A” Frame Hydraulic Luffing Cylinders, fitted with counterbalance valves
  • Wet Bell complete with 4 x emergency on board cylinders
  • Wet Bell Manriding Hydraulic Winch. With Stainless Steel Drum / wire Guards
  • Clump Weight. With Stainless Steel Sheave Pins and Grease Points
  • Wet Bell umbilical
  • Wet Bell umbilical power sheave and roller handling assembly
  • Clump Weight Manriding Hydraulic Winch with Stainless Steel Drum / wire Guards
  • The Winch Proportional Control Valves have Motor Spools for Fine Control
  • Two Integrated 30kW Hydraulic Power Units 3 Phase 380-440 Volt 50 /60 Hz
  • Stainless Steel Electrical Control Panel with Two 63 AMP Industrial Male Bulkhead Plugs for Connection of the Primary and Secondary Electrical Supplies
  • Emergency Stop Located on the Control Panel
  • 24 Volts DC Control System


General Information Base and Winch Skid

Protective Stops are incorporated into the design fabrication, which support the ‘A’ Frame in the stowed position to avoid contact with the winches. 

The hydraulic luffing Cylinders are connected to the base skid and ‘A’ frame clevises with 316 Stainless Steel pins, retained in position with bolted SS keeper plates.

The base frame is inset with a composite non slip corrosion proof grating, forming a safe operational area and walkway for personnel.  Additionally there is an elevated structural pedestal which incorporates the two hydraulic manriding winches and the proportional hydraulic control valves assemblies.  The elevated position of the winches keeps the winch wires clear of the operational personnel working on the base skid.

The winches are integrally piped in 316 Stainless Steel to the hydraulic control valve assemblies, which in turn are connected directly to the supply and return hydraulic supplies from the hydraulic Power Units.

The base skid is additionally outfitted with two inward opening safety gates which remain closed when the Wet Bell is deployed over the side of the vessel.  Incorporated within the safety gates are twin sets of 316 Stainless Steel multi-rollers which are utilised for umbilical handling if the LARS is used with a basket for conventional surface diving (optional)

‘A’ Frame

The ‘A’ Frame movement to the inboard or outboard positions is controlled by operation of the hydraulic control valves.  The ‘A’ Frame is fitted with a main central sheave, where the lift wire is positioned for lifting and lowering the Wet Bell.  Additionally at each end of the top beam of the ‘A’ Frame there is a sheave for the clump weight wire and a stop end for connection of the clump weight wire end termination.

The head of the ‘A’ Frame also incorporates a high intensity spotlight for illumination during hours of darkness and an electrically interlocked trip which activates a failsafe lock-out system if the dive basket is raised above a safe preset level.

Clump Weight

The fabricated Clump Weight design allows the Clump Weight wire to be doubled reeved through the twin sheaves which are situated at each end of the Clump Weight.  This allows free travel of the Clump Weight in the event of emergency recovery of the Wet Bell, using the clump weight.

Wet Bell - 3 Man

This is a 1.35 m x 1.89 m x 2.16 m Wet Bell complete with an integrated overhead fabricated dome with 4 x acrylic windows which will allow viewing from the top half of the Wet Bell directly above the diver’s exit an entry points of the Wet from both sides.  The dome is enclosed within an overhead frame complete with a protective grillage. 

The wet Bell incorporates 4 x 50 litre high pressure emergency air/gas cylinders, Clump Weight wire guides, diver access points from both sides of the cage and seating for the divers.  Hand hold points are situated within the Wet bell and 316 Stainless Steel safety chains are fitted at the diver access points.  The Wet Bell is also equipped with an internal overhead lift point for the addition of an unconscious diver recovery system.

The main structure of is made up of a heavy duty tubular section with the base section manufactured in Heavy Duty ‘I’ Beam to increase the in-water negative buoyancy of the Wet Bell.  The main lift wire connection point incorporates two additional emergency lift points. 

Internal Wet Bell Panel

This will be a custom built panel mounted inside the upper dome of the Wet Bell.  One section will control the divers hot water supply in and supply out to each diver. Divers 1, 2 and Bell man supplies will have independent control panels with air inlets and air outlets together with HP back up supplies from the 4 x cylinders.  There will be a separate section for flooding the Wet Bell dome and pressurising the Wet Bell Dome. 

The Wet Bell will have integral comms at this location.  HP contents will be indicated at the panel from the 4 x onboard cylinders. 

Directly overhead the panel will be a CCTV camera which will monitor the operation of the panel from the dive control container.

Wet Bell Umbilical

The SMP Wet Bell Umbilical comes in optional lengths but for this quotation we have assumed 55 mtrs.  This depends on the working depth of the Wet Bell requirements.  The make-up of the main bell umbilical is as follows:-

  • 4 off ¼” i.d. Pneumo Gas Hoses
  • 4 off ½” i.d. Gas Hoses (4 Gas Hoses provided for further upgrade to a 3 Diver System)
  • 1 off ¾” i.d. Hot Water Hose
  • 4 off DCS0013 Mini TV Cables
  • 5 off DCS0004 Power Cables
  • 4 off DCS0012 Comms Cables
  • Diver’s Monitoring Cables
  • Polyester Fibre Strength Ropes
  • Close Weave Polyethylene Monofilament over-braid

The Wet Bell umbilical is made up of highly flexible braided pressure hoses.  The gas and pneumo hoses have polyurethane liners and reinforced fibre braid layers to offer abrasion protection.  The hot water hose are constructed of the same materials but have a thermo-plastic rubber in the liner. 

All cables for both comms and power are of high quality polyethylene core insulation and polyurethane sheaths are used as standard materials to meet the standard diving application requirements.  All hose end fittings are fitted with swage phosphor bronze fittings.

Wet Bell Umbilical Power Sheave

The Wet Bell LARS is equipped with a fixed position Hydraulic Umbilical Handling wheel mounted above the winch section on a vertical stanchion.  The rotational direction, speed and tension are controlled at the dedicated proportional control valve station.

The Umbilical handling wheel is manufactured to suit the minimum bend radius of the Wet Bell Umbilical which is client specific in terms of services required.

Additionally there is an umbilical roller quadrant mounted on top of the Wet Bell ‘A’ Frame for safe overboard handling of the umbilical.

Manriding Winches

Two hydraulic Manriding Winches are fitted to the SMP Wet Bell LARS.  The Winches are fitted with 16mm and 13mm rotational resistant galvanised steel wire ropes, which are crush resistant and reduce sheave wear.  The winches are additionally fitted with robust 316 Stainless Steel drum / wire guards.

Both hydraulic Manriding Winches are planetary type Winches of high performance with many years of severe service operation.  The Winches are powered by high efficiency gear motors designed specifically for applications to provide smooth application. 

The motor torque is transmitted and multiplied by the high efficient gear train enclosed within the Winch drums.  All rotating components are supported by high anti-friction bearings and run in oil to minimise friction.

The load control system is maintained by a patented brake valve.  The brake valve is also backed up by an internal multi-disc hydraulic release safety brake.  Additionally an overrun clutch permits a free rotation through the brake in the hoisting direction only with immediate lock-up when the hoisting operation is completed.

Hydraulic Power Units (HPU)

The Wet Bell LARS is equipped with two single independent 30kW Hydraulic Power Unit mounted within the confines of the LARS structural footprint. 

The Hydraulic Power Units are each equipped with 200 litre hydraulic reservoirs which support the electric drive motor mounted on noise suppression rings, bell housing, drive coupling and the fixed displacement submerged hydraulic pump complete with suction strainer.  The hydraulic reservoirs are outfitted with side mounted inspection hatches, return line filters, sight glasses and fill points with desiccant breather.  The installation of the two hydraulic power units gives the system 100% redundancy, with separate dedicated primary and secondary supplies in the event of failure of the primary unit.

The hydraulic circuitry is fitted with non-return valves and over-pressurisation safety valves which operate as and when required during the operation of the LARS.  The unit is equipped with a shell & tube bundle seawater / oil cooler which control the hydraulic oil temperature, on the return flow to each oil reservoirs.

The unit is fitted with 3 x 3 port diverter / change over valves with linked handles, which can be switched very simply from the primary to the secondary hydraulic system circuits, without the need to disconnect or operate multiple changeover valves.

The Hydraulic Power Unit electrical 3 phase 380 – 440 volt distribution and 24 volt control system is built within a 316 Stainless Steel enclosure. The enclosure incorporates all the necessary controls to operate the system safely.

LARS Electrical Control Enclosure

The main electrical enclosure has two independent incoming main supplies via two 63 AMP plugged connectors.  The mains supplies can be selected and switched at the main isolation switch giving 100% power redundancy. HPU No 1 and No 2 can also be selected and switched at the main electrical enclosure and activated by independent start / Stop buttons, an emergency stop button is also incorporated.  In addition a limit switch override reset button is installed to allow the basket to be lowered if the high basket limit is activated during operation.  A Status indicator light is installed to confirm the 24 Volt control power is available.

LARS Lifting and Handling

The SMP LARS is supplied with the 4 off main lift padeyes which are bolted onto the main structure. This enables the padeyes to be removed for regular proof load testing as required by regulations without disturbing the ‘A’ Frame sea-fastenings onboard the Vessel.

In addition the LARS is supplied with a dedicated spreader beam and sling set suitably rated tested and certified for the full weight of the complete LARS, including the basket and clump weight.

Umbilical Storage Basket

This will be a fabricated umbilical storage basket complete with fork lift pockets on the underside of the basket for ease of movement and 4 x lifting eyes in each corner at the top of the basket.  The basket will be built in accordance with the weight of the umbilical with wire mesh sides and finished with a galvanised coating.  A lower access aperture will be fitted to the basket so that the surface end of the wet bell umbilical can be connected direct to the 20’ DNV dive control container. 

Dimensions of basket:   2438 L x 1100 H x 1175 W              

Sacrificial Sea-Fastening Plates

The LARS is provided with a set of sacrificial plates which bolt in position to the LARS base skid and can be utilised for sea fastenings at the client’s location.

Optional Extras

Portable Remote Electro / Hydraulic Console for operation of the System remotely.  This can be positioned inside the control cabin.


Depth Capability: 100 m Operational Depth

Design Appraisal: Lloyds Register of Shipping

Design Approval: Lloyds Register of Shipping

IMCA Compliance:   IMCA D023 & IMCA D018 (and D037 optional)

Wet Bell Cylinders: 4 x 50 Litre Cylinders 300 Bar rated

Wet Bell Dimensions: L 1340 mm x W 1890 mm x H 2163 mm

Length (approx): 4200 mm

Width: 2438 mm

Height (Operational): 4100 mm

Weight: 7000 kg

Hydraulic Power Units:  2 x 30kW HPU Tank Mounted Submerged Vane Pump

HPU Electrical:   3 Phase 380 – 440 Volts 50 / 60 Hz

HPU Oil Capacity:   2 x 200 Litre Hydraulic Tanks with Inspection Covers

HPU Working Pressure: 100 bar @ 90 Litres / Min @ 1450 RPM

Seawater Oil Cooler: Shell and Tube Type Seawater 45 Litre / min @ 5 bar Max

Wet Bell Winch Manriding:  16 mm Dia x 60 Meters Anti Rotational Wire Rope

Clump Winch Manriding:  13 mm Dia x 120 Meters Anti Rotational Wire Rope

For instant service contact our sales team
Telephone +44 (0)1772 687775

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