Exterior Engine compartment vent cover

[tawcat]

Somewhere I remember seeing an ad or something for vent covers.

We don't do a true winterization, however we do install a boatsafe heater. So we're wanting to cover the vent fins so as to keep the warm air in and cold air out.

Anyone have suggestions on how to accomplish this? We do run our boat during winter months, eagle watching, so it needs to be something that is en easy on and off method.

Thanks so much.