Passenger protection was the most important concern in developing the Toro transfer capsule. During immersion and self-righting testing, engineered test dummies provided a close simulation of expected load distributions. (Images courtesy of Reflex Marine Ltd.)

The objective of crew transfer is simple – to move personnel safely and efficiently. Meeting that objective, however, can be complicated by a number of variables, including weather conditions, sea state, and geographical location.

Transferring crews is a risky business, but crew transfers can be carried out safely, even in demanding conditions, if the right equipment is in place.

Crane transfer risks

Transfer incident data collected from around the world provide an understanding of what goes wrong during transfer operations. The primary risks are falls, heavy landings, side impacts (usually during pickup), and occasionally immersion.

Recently, industry best practice has improved, although implementation of higher standards is not yet as widespread as it could be. This can be attributed in part to a lack of widespread understanding of the risks, a lack of understanding of the potential solutions, a strong attachment to traditional practices, and a reluctance to invest for economic reasons (often connected to some of the other reasons listed).

Traditional crew transfers rely heavily on human responses. Today, with the workforce aging and more inexperienced crews being employed, carrying out a transfer becomes an even greater challenge.

It is widely recognized that, where possible, it is better to engineer risks out of the system rather than rely on unpredictable human responses. Once there is a sound appreciation of the risk drivers, changes can be made.

A transfer device recently introduced by Reflex Marine was developed using a risk-based design process that applies ergonomic principles commonly used in the motor industry. The resulting device, called the Toro transfer capsule, is optimized for safety and ride comfort and is capable of achieving high transfer rates even in harsh weather conditions.

Design objectives

In an effort to answer the most critical needs of a transfer system, the project team defined the features required for a new device.

Passenger protection was the most important concern. The protective features incorporated in the new capsule were based on analysis of a database of more than 70 crane transfer incidents, which included seven fatalities.

The design also had to accommodate high transfer rates. The goal in the design process was to ensure passenger entry and egress could be achieved in less than five seconds. Achieving this objective provides economic benefits to operators while it reduces risks, requiring the transport vessel to operate for less time close to an offshore structure.

Logistical convenience was another consideration. As it is designed, the new device can be easily shipped and stored. It fits into a standard shipping container and can be provided with a dedicated protective shipping and storage box.

The capsule is designed to allow a stretcher to be carried onto it conveniently within a protective environment. Shock absorbing features provide important protection to the casualty, particularly when transfers have to be carried out in harsh weather. A wide range of engineering elastomers and foams were evaluated to identify materials that provided excellent shock protection and a durable interface.

Finite element analysis identified the parts of the capsule that would see the most stress. That information was used to create a unit that has a minimal number of critical load path components, all of which are internal to the unit (reducing the likelihood of damage or degradation).

Achieving good passenger ergonomics was considered to be central to the success of the project. Key elements were defined as:
• A highly protective riding position;
• Good spatial awareness and wide field of vision;
• Good access arrangements, especially to allow rapid egress;
• A strong sense of security (protection) and comfort; and
• A sense of freedom to exit quickly and easily when required.

Following several cycles of modeling and refinement, the desirable ergonomic features of the device were defined.

The final unit incorporates a riding position that provides comfort, assurance, and protection to the rider. An inclined seat base, aided by elevated hand grips, allows passengers to rise from the seat with minimal effort. The space designed to accommodate the limbs and body provides a stable “braced position” and impact protection from all directions. The lower body is stabilized by a pommel seat profile (like a horse’s saddle) coupled with a tilted foot rest. An engineered foam cushion acts as a shock absorber. The limbs are partially extended to increase responsiveness to shocks. The profile headrest is designed to offer protection against whiplash and offers axial and lateral support to the head. The elastomer material also increases comfort and reduces the risk of injuries. Passengers have a wide field of vision and can move quickly and effortlessly to and from the unit.

In addition to featuring many ergonomic features, the new Toro capsule meets key operator demands. This cost-efficient device provides a protective transfer environment, a wide weather operating envelope, and high transfer rates for a wide range of industry applications.

Proof of design

The capsule was put through a rigorous verification program to confirm its performance. The evaluation included stability testing at a full range of loading scenarios. The unit provided a highly stable platform, remaining stable up to greater than a 45º angle.

Impact and load testing were also carried out. Extensive load tests included dynamic drop testing using accelerometers and associated instrumentation to determine passenger decelerations. The unit also underwent immersion testing. During immersion and self-righting testing, engineered test dummies provided a close simulation of expected load distributions. Excellent self-righting responses were shown in all scenarios Verification of the unit was also carried out by American Bureau of Shipping. Capsules will be certified to EC Machinery Directive EN 1050, EN292 Parts 1 & 2 (CE Approved).

Managing operational controls

To achieve safety and efficiency, operators of this device must assure that best practices are implemented for transfer solutions. These should include:
• Engineered protection to reduce reliance on inconsistent human responses;
• Risk awareness to ensure that key personnel are aware of the typical risks involved in crane transfer operations;
• Clear procedures and operational controls to help ensure consistent results; and
• Training and support so that crews have the knowledge and tools to conduct operations as safely as possible.

Continued focus on risk and operator support will help to ensure that safe transfers are accessible to the whole offshore industry and not just a select few.

Comments