UK-based The Rothen Group – a

specialist in marine plant hire and civil engineering, piling hammer hire and ecological services – has one of the largest fleet of crane boats in the UK. These crane boats, that are primarily used on cannals, are equipped with knuckle booms to deliver lifting solutions to sites that land-based cranes cannot reach. We speak to Russell Sweet, head of workshop, and Dan Harding, head of marine plant hire, at The Rothen Group to find out more about their bargemounted knuckle boom crane boat fleet…

How many knuckle boom cranes do you have in your crane boat fleet?

Dan Harding (DH): We currently have 21 crane boats in our fleet, and typically we expand our fleet by one to two crane boats per year as we are seeing a lot of demand for lifting works from the waterways.

What makes/manufacturers do these cranes include?

Russell Sweet (RS): Most of our crane boats are installed with HMF cranes but we do also have Palfinger, Hiab, and Bonfiglioli cranes within our fleet.

What lifting capacities and outreach do these cranes cover?

RS: Our fleet ranges from 6 to 50 tonnes per meter, and our maximum lifting capacity is 2.71 tonnes at a 14.4 metres radius. We have the ability to lift nine tonnes directly over the side of the boat to make operations efficient. We maintain a diverse fleet so we can tailor equipment choices to specific project requirements and operational contexts.

Are your cranes electric or diesel powered?

RS: All our cranes are powered by diesel boat engines.

How are they operated?

RS: We can operate most of our equipment both via controls on the crane, and through remote control on a ‘chest pack’. These remote control systems are equipped with a six-lever control system that allow operators to maintain a safe distance from the crane and the load, reducing the risk of injury during operations.

Not only is it safer, but remote lifting makes for a more flexible and accurate lifting operation. The remote control system provides real-time operational feedback, such as load percentage and crane status, enhancing decision-making and efficiency. Operators can see where the load is and visibility of what is being lifted and where it is being lifted to is better, meaning overall decision-making and efficiency is improved.

When did you get your first crane boat?

RS: The Rothen Group is ten-years-old this year, and I’ve been here since day one, so ten years ago! In that time we have gone from six boats through to having over 200 boats in our fleet which, alongside our crane boats, include digger hoppers, pontoons, hoppers and more.

What are typical applications for these boat cranes?

DH: Our crane boats are used for a wide variety of different applications but, typically, we are out on the waterways lifting lock gates out of the water when they’ve been damaged and need changing or installing sheet piles to repair collapsed banks on canals. We also hire our crane boats out for long-term projects. In these scenarios, they’ll be hoisting construction materials, lifting equipment like diggers or other heavy machinery, and they can even be used as ‘man baskets’, similar to a cherry picker application.

What makes knuckle boom cranes particularly suited to your type of work (over, say, fixed straight booms or telescopic boom cranes?)

DH: Flexibility and versatility. We think of them as the ‘Swiss army knife’, as they will do everything that other types of cranes will do but, unlike telescopic or fixed straight boom cranes, you can get a better angle of lift with knuckle boom cranes. You can work and pick up anything from anywhere within the radius of the crane and when you’re on tight canals and waterways that is a very specific advantage.

Do you or the crane manufacturers mount the cranes on the boats?

RS: We will build and fabricate the boats first; then we mount the cranes to our boats ourselves. We do, however, work in collaboration with the crane manufacturers to ensure that everything is in accordance with their specifications.

Do you collaborate directly with the manufacturers on these installations?

RS: We do, yes. To give an example, we will do a declaration with HMF to say that the crane is going on a static mount. Once the boat is fabricated and the crane is mounted, HMF will come out and do a Pre-Delivery Inspection (PDI), where it helps set up the crane and checks it’s all been mounted correctly. During the PDI we will run a load test in conjunction with HMF, where we lift 125% of the crane’s maximum capacity.

What particular considerations need to be taken into consideration when mounting a crane on a boat?

RS: Stability is the main thing as we’re operating these crane boats from the water. We consider the weight of the vessel once the crane is installed, as that makes a big impact on stability. If you have a short, light boat then we can’t put a heavy crane on it as it just simply won’t be safe to operate.

Are customisations or modifications required to mount the cranes on the boat (as opposed to on a truck)?

RS: Yes, all our cranes we order have to be modified so that they don’t have the support legs and associated ground bearing pressure sensors. As we operate our cranes via the water we use our own stability legs instead to secure the boat. Our crane boats are also designed to have the crane fold neatly into the deck, so that there is room to transport other items such as construction materials, helping with general logistics planning on projects.

Do any particular considerations need to be taken into account when using the cranes in a water environment as opposed to land based cranes? Are maintenance requirements the same or greater than land-based knuckle booms?

DH: For cranes, the Lifting Operations and Lifting Equipment Regulations (LOLER) stipulate that they should be checked once every six months when lifting people, but if not lifting people, then it is once every 12 months to ensure they are safe and fit-forpurpose. Even though our cranes are not predominantly lifting people, we still stick to checking our crane boats once every six months as we believe this is best practice to ensure the health, safety and wellbeing of our crew and third parties that we work with.

Alongside this, before going out to a job, we will put together a Lift Plan. We use the ‘traffic light system’ which takes into consideration buoyancy of the boat taking part of the weight to help lower ground bearing pressures on the bed of the canal. We work closely with our navel architects to produce these calculations every time. Doing this means we know what we pressure we can safely exert on the ground and canal bed we’re working from, and determine how much we can lift under different configurations.

Who does service and maintenance on your crane boats?

RS: We do the servicing and maintenance of our crane boats ourselves, as we have an experienced workshop team that are fully trained on all the equipment. We can also self-assess and repair our crane boats as we have two LOLER-qualified plant inspectors within our team, me being one of them, and carry a wide range of spare parts so our plant and machinery is always in tip top condition. As part of this, we have to maintain our qualifications by retaking the certification and training course once every five years.

How do you ensure the stability of the cranes/safety of the crew when lifting on water? Do you use any control systems / anti-tip technology?

DH: To ensure the safety and stability of our crane boats we will calculate the ground bearing pressures when we are putting together our Lift Plan. Included within this is calculating water buoyancy, which in simple terms is looking at how stable the boat will be once it is jacked up a certain percentage out of the water, and with the weight of the vessel then transferred instead to the stability legs. Once all rigged and set up, we will perform a test lift to ensure that everything is safe.

Do you have plans to further expand your boat-mounted knuckle boom crane feet?

DH: We do, yes! We have already ordered two more cranes this year, so our fleet will expand to 23 crane boats overall. We are seeing the need to invest because there’s an increasing demand for the hire out of our crane boats, whether that is from mobilising them to repair canal lock gates caused by accidents from more leisure boaters or maintaining sections of the waterways caused by weather changes and land slips and leaks.

We have also seen more long-term hire of our crane boats to help with major infrastructure repair projects, such as maintaining the underside of bridges and concrete abutments that hold up sections of highways and flyovers.

What’s next for The Rothen Group in terms of crane technology on boats? Any innovations in the pipeline?

DH: Innovation is always top of mind when we look at our next crane boat, and indeed, look back at our existing fleet, too. One particular piece of innovation that we are particularly proud of is our telescopic stabilising legs, which we trialled with our latest crane boat, the Brunel. These are extendable legs, so that they can be shortened and lengthened as needed to the depth of the canal. The key benefits here are time and labour saving – instead of needing two people to lift what is quite a heavy bit of kit we can simply extend the legs and stick a pin in at the desired length. We have now retrofitted all our crane boats with these telescopic stabilising legs seeing how successful they were.

For more information about The Rothen Group, please visit: www.therothengroup.co.uk