I was looking through the forum and someone mentioned tent condensation and said someone "guy out the fly". Can anyone explain what this means?

It means to tie line to stakes in order to take the slack out or tighten the pitch.

Ah I see, thanks.

Guying out the fly ventilates the tent better. Ventilating the tent moves moisture out. People don't like to do it because they imagine the tent will be warmer if they block ventilation - that's just a tipoff they have the wrong sleeping gear, because warmth is what your sleeping gear is for. Then they get upset when they sit up in the morning and water rains down from the inside of the fly, and return the tent to REI because of "too much condensation."

Round and round it goes.

If you have a single wall shelter, expect condensation in high humidity areas/conditions. I've set up a silnylon shelter I had above a lake outlet, 40' in elevation and had high condensation in it. No rain in site either. It was floorless, so I think that adds to the issue too.
Duane

If I use my Big Agnes Fly Creek in temps below freezing and don't create some ventilation, it develops it's own weather system. The condensation is horrible!!! Big Agnes made a design mistake, running solid panels higher on the sides which restricted ventilation. They changed it on the higher end version of the tent. This happened once when I first got the tent. After that we've taken to using forked sticks or a pile of rocks to lift our guy lines on the fly both up and out from the tent body, allowing good cross flow. We also never completely shut the front zipper, and actually peel the vestibule flap back a little. Only required when its near or below freezing or very high humidity and below 50. Some tents are worse than others, it all has to do with ventilation. If your tent has a mesh body that comes down all the way to the floor tub and the fly is pulled out away from it when it's pitched, you won't have much of a problem. My heavy 4 season tent has lots of ventilation, but will still condensate our breath on the fly, as it has done several trips this year when it was sub-zero. Years ago I would clip cheese cloth across the top of the tent to collect the condensation, then would carefully unclip it and throw it outside in the morning. Now I just allow for better venting. I also like guying out the sides of the fly in the summer to allow any breeze to find its way in.

Thanks for all the replies everyone. I don't plan on setting up camp in cold weather (yet) so the trade off between warmth and ventilation isn't an issue. That and I have a bag that's rated for 20 degrees for the three seasons I plan to hike.

There are lots of ways to avoid internal condensation in a tent. If I sound like Henry Shires of Tarptent, that's where I learned!

Make sure the tent is well ventilated. Especially avoid a tent which has the screen doors slanting inward towards the top, through which the rain can come. With those, you have no choice but to close the solid door up tight even in the merest drizzle, and it will be a sauna inside. You want to be able to leave the solid door open in the rain, unless it's really windy with horizontal rain (in which case you don't have to worry about ventilation).

Avoid, if possible, camping in damp areas such as next to streams or lakes (you should be 200 feet away anyway for LNT purposes), in the bottoms of valleys, out in a meadow. Stay off grass (which puts out moisture of its own) if you can. Of course you can't always avoid such situations, but try. Under trees (if they're healthy), you'll get a lot less condensation. On a knoll (if not exposed to lightning) is also drier because there will be more air movement.

Putting two people (or one person and a good-sized dog) in a tent designed for one person can also cause more condensation, since the tent was designed to ventilate for one.

I personally prefer a single-wall tent where I can wipe off any condensation that occurs. Your Mileage, of course, May Vary!

If you expect condensation then get a slightly over-sized tent. Particularly if it is a single wall. Moisture on the ceiling is fine, if it stays there! But if you are always brushing up against the ceiling or walls you will get wet.

I find that when I camp in humid conditions where it goes below the dew point at night and it is calm, no matter how I set up, even with the door wide open, I still get condensation. Some tent designs do not allow much "guying out". You have to carry extra pegs on some tents to set it up for ventilation.

Condensation is also a problem outside the tent when you are out in the open. I camp above timber a lot. A few times I have arose early and put my gear outside the tent, and bam! temperature drops below dew point and moisture literally oozes out of the air and all my stuff gets instantly wet before I have the chance to pack it! If you get under the cover of a tree, this usually will not happen.

Just for informational purposes, I have the Fly Creek UL1. Any thoughts condensation issues with this tent?

Edit: I would also like to say thank you for the info and suggestions.

I have one of the older Fly Creek Solos. I have had condensation form on the upper part of the rain fly but it has never gotten through the inner tent. When I pack the tent with condensation, I just turn the fly inside out, give it a good shake and stuff it in an outer pocket of my pack. The inner tent goes in my pack. If the weather is right, I will pull the fly out when I stop for lunch and spread it out to dry. I also have a Zpacks Hexamid that I have come to like a lot. The Hexamid is more prone to condensation and thus I need to be more careful with camp site selection and with getting a good pitch. The nice thing about the Cuben used for the Hexamid is that it doesn't sag when it gets wet the way the silnylon Fly Creek fly does. There is no need for midnight guy line tightening with the Hex.