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Minimising bio fouling in storage or lay up.

As more of the implications of the COVID-19 crisis become clearer, there is growing evidence of a significant number of ships being used for storage or being laid up. These two ship conditions look likely to be a significant feature for the rest of 2020 and beyond.

Dozens of cruise ships (up to 80% of the global cruise fleet) are laid up in locations including Dover, Miami, the Isle of Wight, Edinburgh, Grand Bahama and Manila Bay.  

VLCCs and other tankers are being used as crude oil storage facilities with reports of more than 30 vessels off California alone.

It is estimated that over 10% of the world’s container fleet is already laid up, and about 15% of the bulk carriers were removed from trading as major bulks such as the transportation of iron ore and coal including their products shrunk.

The offshore sector is also stacking floating assets owing to lower oil prices, driven by over supply of crude oil and severe demand reduction for products.

Whether used for storage or going into lay up the industry is engaged in what can only be described as a significant and widespread “operational pause”. 

Ideally the location for this pause should have a number of characteristics; close to a relevant trading area, easy accessibility, adequate provision of services, good security, moderate climate, to name but a few. One of the factors which is perhaps not always given enough consideration when choosing a location is biofouling probability.

The reason this is important is the growth of biological organisms during a prolonged period of inactivity on the hull and propeller can speed up corrosion and fouling and can increase hydrodynamic resistance by up to 40%. This results in increased fuel consumption and adverse vessel performance expenses. Remedial drydocking and repainting may be necessary to restore performance with costs which can run into millions of dollars.

These costs can be avoided or mitigated if identified early. The factors that affect the rate of biological growth are well understood and predictable. They include water clarity, water temperature and salinity, current and wave action, hours of daylight and the concentration of chlorophyll.

These parameters are variable in time and space, but detectable and monitored, both on a global macro scale and on a local micro scale. In general bio growth rates are fastest in the summer months and in tropical waters, but optimisation of the factors on a micro scale can sometimes make considerable difference to fouling development even within a relatively small area.  

Multiple remote and local data inputs can be integrated and analysed to support location selection to minimise the rate of biofouling and to provide location monitoring which permit early cost effective interventions and problem free reactivation.

Stay safe.

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