Ship's A-frame Monitoring System

A ship’s hydraulic A-frame is an important asset on-board a vessel and is used for lifting, moving, and deploying all types of equipment to perform its mission and deliver objectives.

Keeping the winch and A-frame system well maintained and working within design parameters is essential to safe and accurate operations and continued equipment availability. With extensive lifting, winch and crane experience, Water Weights have developed an integrated A-Frame Monitoring System.

The package is highly flexible and visually represented onscreen for quick and easy reference with additional audible and logged information during critical A-frame and winching operations.

The overriding benefit of the monitoring system is safe and effective operations.

By providing clear and concise information to the operator in an easily recognized graphical format additional data is provided with minimal increase in operator workload. The audio- visual alarms warn the operator action is required when the display is not being monitored.

Other features such as data logging are transparent to the operator. The system is programmable for most A-frame/Winch systems and is fully scalable allowing additional variables such as wind or sea state to be integrated.

The wireless sensors allow simple new or retrofit installation. Sensor cabling is not required allowing quick install in hard to reach locations or in areas where conventional equipment may constitute trip hazards.

The standard Monitoring package consists of a suite of ultra rugged Battery powered wireless
telemetry measurement sensors. These sensors communicate acquired data back to the HMI
allowing real time alarms, data logging and visual representation of the A frame position and
loads during operations.

Standard Package Provide
A-Frame Angle
A Frame Radius
Vessel Angle/attitude

Typical Features
Color HMI Touch screen display
Extremely simple operation
Telemetry wireless sensors
Load versus angle load chart
Graphical A Frame position display
Safe Load Indication
Visual and Audible Alarm system
Data logging lifts and utilization
(removable memory)
Long Life Battery powered
Battery life monitoring

Optional Features
Sea and Wind Conditions
Rope payout length/Speed/direction
Winch Hour Meters
Winch and A Frame utilization data
Inspection reminder
Trip system (winch/A frame inhibit)
Portable hand-held display for Riggers

If you have any questions or want to discuss your application, please click here, fill out the relevant information, and we will contact you promptly.

200 tonne Load for Comparison Reading of Crane's SLI

Following successful load testing on-board the Liftboat 'Seajacks Kraken' Water Weights were requested to assist a client in the load testing of it's sister ship the 'Seajacks Leviathan'. Both vessels are self-propelled, self elevating liftboats for use in harsh environmental conditions. The vessels facilitate installation and maintenance of offshore wind turbines, as well as the service and maintenance of offshore Oil and Gas platforms in the North Sea.

The client required a 200 tonne load to be applied in increments to facilitate comparison readings of the crane's safe load indicator. Water Weights bags are ideal for this type of testing due to nature of the bags' capability in achieving various loads, by simply filling and draining without having to rig multiple stacks of solid weights. The whole test was achieved using six 35 tonne water bags configured in two sets of three bags hung from a single Water Weights Load Measuring Shackle.

All set up, rigging and testing were completed in one day much to the client's satisfaction. For further information; you may find us online @ www.waterweights.com

Overhead Crane Load Measurement Systems

One of the main difficulties encountered by crane owners, with many existing crane load monitoring systems, is the difference between the load displayed on the indicator and that actually hanging on the hook during the lifting and lowering operations. Controlled tests have demonstrated changes in load reading of up to and exceeding 20% between lifting and lowering the load. These errors are frequently caused by friction losses on in sheave bearings on multi-sheave cranes. Our experience and knowledge in resolving these issues provides the confidence in promoting effective solutions to these challenges.

There is a distinct difference between a Crane Overload Protection Device (COPD) and a Crane Load Monitoring System (CLMS, and therefore the equipment to fulfill these applications can be significantly different if both requirements are to be met.

The COPD is there to provide either an alarm or control interlock that trips when a preset load is exceeded. It does not have to display hook load or undertake any other function on the crane described above. A simple CLMS or below-the-hook load measuring device can consist of a portable load measurement device such a strain gauged load link or shackle that is positioned between the crane hook and the load.
The CLMS has a function to display load information to the user for real time operational decisions to be taken or to calculate crane operating performance that is used in inspection and maintenance programs.

More comprehensive CLMS systems consist of a range of sensors/transducers to measure; load, angle, slew and payout all connected to an integrating instrument that calculates load information plotted against component position and crane body. This system is frequently called Crane Safe Load Indicator (SLI).

For clients wishing to utilize the data collected for determining crane usage and inspection criteria, we offer an array of sensors with a data collection package that enables the user to gain access to this information either in close proximity to the crane or at remote locations.

Note: Water Weights supplies integrated measurement systems for electric overhead traveling cranes. Each system is custom designed to suit the precise requirements of the crane. A simple, low cost, system can comprise of a load measurement transducer positioned at point within the crane rigging and instrument incorporating relay cut off which is set to operate in the event of a crane overload. Other devices can be added to these systems such as; large scoreboard displays, analogue and serial outputs to interface with other equipment and wireless transmission of load information to portable hand held display instruments through to a visual graphics display providing real time information and data storage of the cranes movements within defined operating periods.

Load and Force Measurement

The need to accurately measure load, strain and force, or a combination of these, is an essential requirement for a significant number of industrial, environmental and social applications. Whether it is weighing ingredients in a food blending process, measuring weight on a crane hook, or measuring strain and force on the ocean floor, Water Weights provides reliable and cost effective solutions.

First of all, Let's define the instruments at the heart of the topic.

What is a load cell? A load cell is a precision machined billet of a specific material (picked during the design process), with strain gauges bonded at defined points accurately measuring the deflection in the billet when a force or load is applied.

There exists many types of load cells exhibiting different measurement characteristics and performance in respect to accuracy and repeatability. Typical designs include: compression column, shear beam, double shear beam, shear web, tension, tension & compression, single point, load pin, etc...

The mounting and loading of all load cells is critical to its performance.Type selection is typically a product of application and performance requirements.

What is a strain gauge? A strain gauge is a resistive network device which is powered by a DC voltage, generally termed “Excitation Voltage”, where the resistance changes if its dimensions are altered by the material it is bonded to. Typical excitation levels are 10, 15 and 20 volts DC with outputs from the strain gauges in milli-volts, where a milli-volt is equal to one thousandth of one volt.

How does a load cell work? When a force or load is applied to the machined billet it changes its shape. This shape change causes deflection in strain gauges bonded on to the billet changing the resistance of the strain gauge, which in turn changes the milli-volt output from the strain gauges.

Provided the load cell billet is not subjected to a force or load that exceed its designed operating capacity, the billet and the strain gauges will return to their original form/shape when the force or load is removed. This characteristic enables the load cell to operate within a predefined accuracy and repeatability tolerance without fatigue.

The applications are numerous incorporating standard and custom designs interfacing exactly with specific equipment and processes in industry.

Some of our applications include:
• Content weighing of vessels, tanks, bins, silos, reactors and presses
• Tension measurement in tethers, anchor and mooring lines, risers and umbilicals
• Mass measurement of slabs, billets torpedo cars, ladles and tundishes
• Strain measurement in structures, solid risers, strip & wire, and textiles

For more information visit our load measuring systems page at http://www.waterweightsinc.com/en/load-measurement.html

Guidelines for Safe Use of Water Weights

Things to know and safe use guidelines

1 When laying the water bag on the ground to commence rigging, beware of any sharp

objects that may puncture the water bag.

2 Beware of your surrounding workspace, again to prevent any damage to both equipment and personnel.

3 Ensure the bag is properly secured before commencing filling.

4 Check for any obstructions around test area and ensure you know where the water is to be dumped after the test is complete.

5 Do not hang any additional load off the water bag harnesses or handling straps.

6 When hanging two or more water bags together, ensure filling attachments are facing outwards. This prevents the emptying trunk from getting trapped in the middle of the bags.

7 Do not tamper / remove any of the water bag rigging. If you need to discuss any aspects of this due to a specific problem, please contact Water Weights first.

8 Never walk away from the bag when filling / whilst test is being conducted and never walk under the load.

9 If more than three water bags are to be used together, please contact Water Weights to obtain a rigging arrangement drawing.

10 Water bags should not be used when wind speed is greater than 25 knots.

11 Although all fire hose fittings are standard adapters, other types are available on request.

If you are in any doubt at any time, please contact Water Weights. We would be pleased to advise you on any job or rigging application.

For more info visit www.waterweightsinc.com