Anybody who’s ever stepped off a solid jetty and into a small boat (or watched some unfortunate person do so on YouTube) will know how easy it is to lose your balance and end up in the drink. So imagine how tricky it must be transferring a massive load weighing 250 tonnes from a solid dockside to a floating barge.
The only way to prevent a disaster as a load of this size shifts from terra firma to the floating barge is to constantly adjust the buoyancy of the floating vessel to compensate for the changes in load, and that is done by pumping water into and out of a series of chambers within the barge’s hull.
The Sedgefield, UK depot of leading pump hire company Sykes Pumps is something of a specialist in this kind of work, regularly assisting clients in the former shipbuilding stronghold of the North East.
In March 2014 the company carried out a textbook pumping contract on a ‘load-out’ for client Titan Heavy Transport of Wallsend, Newcastle-upon-Tyne.
The job involved moving a 250 tonne crane onto a barge moored alongside a wharf on the River Tees. Titan Heavy Transport uses self-propelled modular trailers to transport loads of this size. This is done by assembling the trailers underneath the load and then extending the axles to raise the load off the ground, but when these trailers are driven onto moored barges, a load shift occurs that must be constantly counteracted by adjusting the buoyancy of the barge.
After assessing the size and nature of the project, Sykes Pumps delivered and set up 18 of its GP150M diesel pumps to serve the eight ballast tanks in the barge’s hull.
Despite the highly specialised application, the GP150M is a general-purpose pump, commonly used for de-watering excavations and for general fluid transfer duties. Each GP150M pump is capable of pumping water at a rate of up to 90 L/s (324 m3/h).
A load-out job such as this requires not only large numbers of pumps but also a great deal of manpower and expertise. “It’s very labour-intensive,” says Paul Keogh from Sykes Pumps’ Sedgefield office. “You need a lot of hands on deck – literally – to set up the pumps and maintain a balance during the operation.”
His colleague, hire manager Richard Box, explains that preparing for the load-out is a lengthy process. “On this project we were on-site for about a week. You have to set everything up and plan the load-out meticulously,” he says.
Preparation is vital. But the actual transfer of the load is done in one non-stop operation. “It only took about two or three hours to get the crane off the dock and onto the barge,” says Box. However, those two or three hours can be nail-biting as the massive load shifts onto the floating barge. “Titan has to calculate the load-shift and monitor it constantly. And we have to be ready to pump water in or out of the ballast chambers at the correct rate,” explains Box. Knowing the rate at which the pump is shifting fluid enables a simple calculation to find the tonnage being applied or removed. This directly affects the buoyancy of the vessel and the up-thrust compensating for the weight of the crane.
Added to this, the team has to factor-in the movements of the tide. “We tend to do load-outs on a falling tide and make constant adjustments to increase buoyancy,” says Box. “But occasionally we will load-out on a rising tide too.”
Once the load-out procedure has started, it must be completed without stopping or pausing. For this reason, back-up pumps are always supplied. “On this job we had 18 pumps in total: two serving each of the eight ballast chambers plus two more on stand-by,” reveals Box.
Moving heavy loads is of course Titan’s stock-in-trade. “We do this sort of thing every day,” says director Chris Taylor. “But it’s not an everyday job for most hire companies. There are only a couple of pump-hirers in the UK that can do this sort of work.”
Pumps such as the GP150M units supplied to Titan for this job are most often used for short-term hire where they are required simply to pump continuously until a vessel of excavation is empty or, conversely, full. But on a load-out, they are required to shift precise volumes of water in a controlled manner and must be able to respond quickly to changes in flow.
“To do this sort of contract, you really need knowledge and experience, and we’ve got that at Sedgefield,” says Box. Four engineers from the depot were on-hand throughout Titan’s recent load-out.
Furthermore, not every hirer has pumps in sufficient quantity to supply this type of work. It is not uncommon to supply 50 pumps for a single load-out contract, according to Box
This contract, however, was more typical of the kind of work carried out by Titan Heavy Transport. And thanks to the experience of the team and their attention to detail, the project went off without a hitch. “The guys from Sykes Pumps are experienced in this sort of work and we can be confident that they know what they’re doing,” comments Taylor.