Safer deck systems refined and upgraded

I forrige utgave av Skipsrevyen omtalte vi SDO systemet til Rolls-Royce i artikkelen “Heavy lift funksjon på SDO”. Her følger en mer utførlig beskrivelse av systemet samt informasjon om et system for utlegging av kjetting.

Since the Rolls-Royce Safer Deck Operations (SDO) system for anchorhandlers first went to sea on «Olympic Octopus» in 2006, it has been enthusiastically taken up by the industry. To date, more than fifty ship sets have been ordered.
All of the equipment was developed by Rolls-Royce: some of it was a refinement of existing technology while other systems broke new ground. Towing pins and shark jaws, for example are well known, but the new products have better functionality. Working in conjunction with these is the centring device, comprising two steel sectors which swing up and together. The function of these is to align the wire from the main winch drums with the towing pins. Normally two sets of all these components are mounted ahead of the large stern roller and retract flush with the deck when not in use.
The anchorhandling crane layout is perhaps the most interesting feature of the SDO system. Rail tracks run the full length of the vessel’s cargo rails on each side. Special cranes run on these rails and each crane is equipped with two arms. The arms have separate hands or manipulators, designed to carry out a variety of functions. One is basic lifting and using both cranes, equipment or stores can be moved to any part of the deck. The other is working with wires and chains. Shackling wires together offshore can often be dangerous. If a wire under tension is uncoupled it tends to spring back and also rotate, which can cause attached chain links to flail about the deck. One of the manipulator tools is designed to hold the wire in a controlled grip, allowing it to unwind under full restraint. Another tool enables links to be brought together so that the shackle can be put in place while the arms and shark jaw control the parts to be joined. The crew member only has to insert the shackle pin.
The functionality of the system has now been extended and its capacity increased. The main change is to the cranes where the capacity has been increased from 45 to 55-tonne metres.
A winch is now mounted on the top of the vertical part of the crane. Its wire runs over a sheave mounted part way along the crane jib and then down to a hook. A load of 7.5-tonnes can be lifted at this outreach while a second sheave closer to the crane’s axis allows the lifting capacity to be increased to 15-tonnes at 3m. Each crane now has a heavylift function, allowing objects such as rig anchors to be easily moved across the deck, using either one or both cranes working together.
This new system helps to make deck work safer, by eliminating the need for the usual wires across the deck from conventional tugger winches to kingposts and so to the object being shifted. The refined winch system can be supplied new or as a retrofit for existing vessels with the SDO system.
A further SDO refinement is to the trolleys that move the cranes along the length of the deck. Previously, they straddled the supporting structure. Now, the structure has been modified so that all support is inboard. The outboard side is smooth, with no exposed moving parts reducing the chance of accidental damage.
Safer chain laying
An important part of off shore work is laying out heavy chain moorings to secure rigs and floating installations. The chain links are made of steel in sizes up to 165mm in diameter. The chain wheels on the anchorhandling vessel’s winch, that haul in and pay out these chains, are in proportion, ranging up to 2.7m in diameter and weighing over nine tonnes. Different wheels have to be fitted to the winch to handle the various sizes of chain used for the moorings. Traditionally, changing a large chain wheel involved a trip to harbour and the use of a shore crane, a time wasting diversion.
Rolls-Royce has now developed a system for exchanging large winch chain wheels at sea. The design brief specified that operation should be possible under reasonable weather conditions for anchorhandling operations, specifically up to 4m wave height with the vessel head to sea. As with the other Rolls-Royce SDO equipment, chain wheel exchange is carried out by the crew working from a safe vantage point using radio remote control, leaving them with only light manual operations that can be performed with minimum risk.
The new system is built up from a series of sub-units and a vertical lift arrangement that operate together to provide the required functionality.
– Space around the winch of an anchorhandler is limited, so the spare chain wheels are stowed in a special rack on a deck above the winch, says Jon Slyngstad, applications engineer for off shore deck machinery. – A wheel can be picked out and transferred to the level of the main winch spindles by the traveller mechanism, where it can be aligned with the hexagon drive dog on the winch drum spindle and moved into position.
Installing a wheel on the winch spindle is a three-step process and is carried out remotely. (1) The traveller mechanism takes the selected wheel from the rack. (2) The wheel is lowered and turned to face the right way for the chosen winch spindle. (3) The wheel is offered up to the spindle and secured on the drive hexagon. To remove and stow a chain wheel the process is reversed.
– Four examples of this new system have now been sold, says Ottar Antonsen, general sales manager for off shore deck systems. – They are sized for 152mm chain and will be installed in off shore vessels under construction. The system will be further developed for installation on existing vessels and work is continuing on other products for the SDO ‘family’.
On-board simulation
The Offshore Simulator Centre in Alesund, Norway has developed a mini simulator with Rolls-Royce for Safer Deck Operations. It can be programmed with realistic work operations and is small enough to be placed onboard, for example in recreational areas. It enables crews of vessels to practice operational sequences, increasing individual competence levels and thereby improve safety levels on-board.
Kilde: in-depth Issue 13 2008 Article by: Richard White Editorial Consultant.
Se også SKIPSREVYEN nr. 2/2008 “Utvider offshoreopplæring – Farstad Shipping og Rolls-Royce Marine har utfordret Høgskolen i Ålesund til å utvide sine utdannings-, opplærings- og treningstilbud til offshorenæringen”, og SR 3/2007 “Simulator-suksess i Ålesund – Offshore Simulation Centre (OSC) i Ålesund har fått kontrakt med Bourbon Offshore i Frankrike om levering av to avanserte offshore simulatorer for trening av personell i Frankrike og på Filippinene”.