Barnacles in the main seawater inlet of "MV Waterway" from Boskalis

Company: Royal Boskalis Westminster, Netherlands

About the customer:

Royal Boskalis Westminster is a more then 100 year old company from the Netherlands. Boskalis is a leading global service provider for maritime infrastructure, they own more than 1100 vessels for this purpose. The MV "Waterway" is a so called trailing suction hopper dredger.

In general dredgers are used to  remove  material from the seabed and so clean channels and harbours, or for land reclamation or coastline fortification.  One of the well known projects has been the artificial Palm Islands in Dubai, UAE or the extension of the harbour in Rotterdam.
Merus Rings are used on several vessels of Boskalis in different kind of applications.  In all these applications Merus Rings has shown very satisfying results, so Boskalis decided to go for the main seawater line.

The Problem:

Most vessels need seawater on board. This seawater is used for cooling the engine, for jet water, to produce drinking water as well as technical water in a fresh water generator, or for the pressurized water systems  (hydrofoor) to supply the drinking water taps and the showers on board. This seawater is pumped inside the vessel from the so called sea chest,  below the water line. When taking in seawater all kind of marine growth is coming along with the seawater. This marine life is kept outside by a filtering device, but the pipe which takes in the seawater gets over a period of a year totally chocked up with barnacles and seashells. Even more so as the "MV Waterway", at the moment dredging along the African Atlantic coast and thus sailing under hardest conditions when it comes to marine growth. So it is normal procedure on most vessels to clean this pipe at least once a year. In a vessel like a dredger, this problem might be even bigger, as dredgers are operating near the shore line or inside a harbour, where the water is warmer and the conditions to grow for marine life are better then when sailing the open sea. As this pipe is directly connected to the open sea, the cleaning can also be done only from outside. This means the vessel has to be either in a drydock or divers have to be used when cleaning this pipe section.
To keep this pipe as clean as possible is a very important task, as the water passing this pipe is one of the lifelines of the vessel. Without enough water a lot of processes on board will be badly affected.

The Solution:

A vessel like the "MV Waterway" needs a lot of water, so the pipe is a 24" line. In order that Merus is able to have effect on most of the pipe, the installation should be done as far as possible upstream, or in other words as near as possible to the entrance of the water into the vessel.  As there is limited space, the installation of the Merus Ring, especially one of this size, has been a special technical challenge, but was  finally successfully managed.

The Monitoring:

As told above the pipe is directly connected to the sea and so  the inspection of this pipe can be done also only from outside. When the schedule of operation has allowed app. 12 month after the installation the pipe has been checked as well, and the picture to the right has been taken. The fleet manager of Royal Boskalis Westminster wrote: "Normally after 12 month of operation Jacques Cousteau would be jealous about the amount of sea-life found in this place", BUT the pipe was almost clean. As well it has been observed by the cleaning crew, not only  that there where next to no barnacles left in the pipe, but also the few remaining barnacles could be very easily removed. On an untreated pipe line this is not the case and it takes usually a lot of effort to remove barnacles from the pipe wall.
Next thing Boskalis will do is to check how lasting the Merus ring will keep the pipe clean. But one thing is for sure, the risk of getting a problem with a blocked pipe has minimized a lot. Also the rather expensive cleaning has not to be undertaken as often as before.
To get an overview what else Merus is doing in the marine or in cooling system.