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Barnacles/Biofouling in the main Sea Water Inlet

User: Royal Boskalis Westminster, Netherlands

Royal Boskalis Westminster is a leading global service provider for maritime infrastructure with 100 years of experience. They own more than 1100 vessels for this purpose. The MV „Waterway“ is a so called trailing suction hopper dredger.

MV Waterway (c) JF Hofmann

MV Waterway (c) JF Hofmann

On these ships from Boskalis, Merus Rings had been successful in many applications for the past years. As the results were always good and reliable Boskalis decided to install them at the main sea water inlet.

Most ships use sea water aboard. Typical applications are cooling of the engines, production of fresh water or industrial water in pressurized water systems (hydrofoor) providing showers with water. The sea water is sucked into the ship through the sea chest which is located beneath the water surface. This also brings sea organisms like barnacles into the sea water system. Filters prevent most of these from entering the ship. Often the larvae pass the filter and then barnacles and mussels grow there until the pipe is blocked.

If the ship sails along the cost or in the harbor the problem is even worse as the water is warm and the conditions for the growth of oBarnacles and Mussels in the Water Inletrganisms are ideal. The result is so called biofouling. Under these conditions the pipes need to be cleaned at least once a year. This can only be done from the outside with specially educated divers or in a dry dock.

As the sea water inlet is in many ways the lifeline of the ship it needs to be kept clear at any time.

Merus on the main seawater inlet

The pipe we treated on the MV „Waterway“ has a diameter of 24“. We installed the fitting Merus Ring with a inner diameter of 55 cm.

To ensure that the effect is spread widely we installed our device upstream, close to the opening where the water is sucked in. As space is limited on the dredger it was challenging to install a Merus Ring of this size but we managed to find the perfect place.

The result after the installationPipe free from bio growth after the installation

As described above, inspecting the pipe is only possible from the outside, the sea. Therefore we needed to wait 12 months to see the results of the installation. The picture shows that the pipe is clear – this is a big success compared to what we saw one year before. The fleet manager of Royal Boskalis Westminster wrote: “ Usually after 12 months Jacques Cousteau would be envious regarding the marine life in our pipes.“

Only few barnacles were left in the water inlet though they didn’t stick to the surface and could be removed easily. Whereas at pipes without a Merus Ring this is a tough task.

For Boskalis it is important to see if the effect is lastingly and the pipe stays clear. Nevertheless we could achieve the first goal in one year. The risk of blocking was reduced and the cleaning cycle is considerably extended.

 

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