Airtight?

Vented

Adam,

Vented. The wrapper should cut small u shaped cuts in the perimeter. It needs to breathe to discourage mold. Even vented, it will be like a greenhouse in the sun.

Make sure your wrapper does a good job on the framing. I've heard and seen many instances of damage caused by improper framing. Last winter we had some windy storms on LI. That one in the early spring caused alot of issues.

They now have clamshell type vents that can be shrink-taped over the vent holes keeping it secure (without venting the boat will be a mold farm). I'd also suggest having a door installed. That will allow easy access during the off season to check the Damp Rids or for rodent infestation. Another suggestion would be to tape over exhausts, and other hull openings that make great entrances.

Have vents. If you can't find the clamshells or don't want to pay for them, I used to cut a "V" in the shrink then put white duck tape at the top of the cut so it wouldn't spread. That and the moisture items inside should keep you mold free. For the 17 years I kept my boat up in Freeport, never had a problem.
And the door will come in handy if you want to take a ride down and get inside it during the winter. Also invites the unwanted too, so decide carefully.

And there be the difference between an Eastender and an UpIslander. Not much disappears on the east end. Either way, if someone wants what's on board they'll just slit the wrap. It's faster than opening the door in the dark. Get the door. It's worth it. There's maintenance that can be done during the winter to get a jump on spring and I like to know ASAP if someone or some thing has been up to mischief.

Is that what I am to you Ed? An UpIslander? Next time buy your own lunch. lol

At least now I'm a Warm Islander, down here in the land of yachts and wackos and where it's summer (or close to it) all year long.

Pretty much west of where I am is upisland; part of the city. Every year the east end shrinks. Over the years I've heard of a lot of things disappearing in Freeport. I like to check on my clients boats every 2 weeks even out here.

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.