If the cover is to enable you to store the engine outside you have a problem. When the wind moves the material it will polish off the engine paint work during the period of a winter. Also condensation will build up on the powerhead. They all do but with just the engine cowl at least it has a chance to evaporate again, however with an extra cover it will just collect and build up. It is caused by minute changes in temp whilst the powerhead remains cool. Bit like your kitchen window when the missus is cooking. If the engine is new might be worth taking it off the boat for the winter.