Most hydration based selfpolishing TBT-free antifoulings in practice offer fouling prevention for about 36 months. However, predicting and controlling fouling prevention for longer periods is less simple due to the build-up of thick leached layers. With hydration based TBT-free antifoulings leached layers are the result of some of the backbone of the paint remaining after the soluble components are absorbed by seawater. These remains will, in most cases, increase the roughness of the hull and, as time progresses, the build up begins to affect the antifouling performance.

Whilst antifouling protection for 60 months is often claimed, it is generally necessary for underwater cleaning to be undertaken at some time in the life of the system.

This serves to confirm the likely development of fouling which, unless quickly identified and removed, will add to the miseries of increased costs as roughness further increases and fuel costs rise yet again.