Deck gear will pull its weight
Fri, 10 October 2014
When the Port of London Authority decided it needed a new Mooring Maintenance Vessel (MMV) it was obviously going to lean heavily on its deck equipment.
There was no doubt about the need for the new workboat: the PLA's two elderly salvage shipsCrossness and Hookness had worked the tidal Thames for over 40 years. So, this brand new MMV will take over much of the river operations: it will perform the usual navigation channel markings and mooring placement as well as taking up old piles and anchors, diving operation support and deploying machinery for both salvage operations and even plough dredging to help keep costs down.
So, although the total value of the build is £6 million (the largest single investment for the PLA in two decades), it really will be earning its keep when it gets into service at the end of the year.
The MMV’s deck equipment needed to match the diverse roles so Ray Milner of North Sea Winches explains the company delivered a twelve unit package complete with full hydraulics system to Manor Marine – another arm of MPI Services UK.
Firstly, there’s a big main winch: this had two speeds which gives it 120 tonne capacity at 4m per minute “for when there is some meaty work to be done” says Mr Milner, plus it has a double speed half pull alternative. The winch has a brake rating of 180 tonnes and takes 100m of 64mm diameter wire “so it’s pretty big stuff”, he adds. Further, there’s a low power cable storage reel – basically a giant cotton bobbin – to hold a backup length of the big diameter rope.
However day-to-day operations probably won’t need all that power so a pair of 20 tonne two-speed winches give more flexibility at the lower loads and there are four, 10 tonne tugger winches, each with room for 300m of line that can run at 17m per minute, useful for general positioning and mooring duties.
An anchor mooring winch has been built with room for chain on one side, rope on the other, and this is complimented by three 6 tonne hydraulic capstans for quick wrap and release using fibre rope. Two heavy duty deck cranes give the whole craft a huge versatility.
Underpinning all this is the full hydraulic system. Mr Milner explains that dedicated auxiliary engines provide power to 280hp load sensing piston pumps: these run the bow thruster and deck machinery hydraulics depending on demand: “The idea is that a load sensing system will respond to what the consumers need, running at reduced speed rather than reduced pull.”
And to top it all, all the machinery apart from the anchor winch and capstans can be operated remotely from the comfort of the wheelhouse.
By Stevie Knight