Originally Posted by adambomb
So if I open small portholes and leave them open then that would be good
If you just cut holes the weather (and birds) will get in. You also need to tape the edges of the holes or the entire shrinkwrap may tear. On say a 36' bridge boat I'd put one vent above the forward deck & 2 over the cockpit with the holes facing down. That should give good airflow and protection. Also, build supports. DO NOT put it directly on the boat as you may burn the boat. BTW, if you're planning to do this yourself make sure your marina permits it (most don't). Also, there is a bit af art involved in the torch usage (shrink, but don't burn through). Also, I don't recommend duct tape as it weathers poorly. They sell shrinkwrap tape.