Southbound thru the GSM

[BrianOH72]

I wanted some input on roughly the amount of time needed to start at I40 and end at Fontana Dam? I'm planning on doing this section next month and would like to hear any input. Thanks much!

[TNhiker]

depends upon your hiking speed and hanging out speed.......

it can be done 3/4 days or 5/6 days or however many days you want............

[HooKooDooKu]

Unless you can do 20mpd in steep mountainous terrain, expect it to take at least 5 nights, and that will still make for a challenge requiring 12 to 14 mpd. If you are the type that can only handle 10mpd in mountainous terrain, that's going to take about 7 nights.

[wannahike]

Also dependent on the shelter reservations you are able to get.

[HooKooDooKu]

Also dependent on the shelter reservations you are able to get.
Yea, go ahead and get your permit (https://smokiespermits.nps.gov/index.cfm?BCPermitTypeID=1) as soon as possible. You can make reservations for your entire trip starting 30 days before the 1st night.
At the moment, things are pretty clear IF you're not planing on Labor Day Weekend (several shelters are already full for that weekend). But if your trip includes a Saturday, there's already some shelters that are book full for Saturday nights well on into September.

Without knowing anything about your abilities, my first suggestion would be these shelters (distances and elevation changes are gross estimate while eyeing this elevation profile (http://tnlandforms.us/at/gsmnpat.html)):
Cosby Knob (10 miles, 3,500 of climbing)
Pecks (12 miles, 3,000 climbing)
Mt Collins (15 miles, 2,500 climbing)
Derrick Knob (15 miles, 1,000 climbing)
Mollies Ridge (12 miles, 1,000 climbing)
Fontana (12 miles, 700 climbing, 3,000 decent)

[MuddyWaters]

Only half is uphill
You can be aggressive in second part
You can call and change reservations as you go too also, if you have Verizon service.

[BrianOH72]

I'm familiar with the back country permit needed however, I wasn't aware about making reservations for the shelters as I thought it was first come first serve. Also if the shelters are full am I able to use my hammock or is that still prohibited?

[HooKooDooKu]

First Come First Serve is only for those with "AT thru hiker" permits. To obtain this permit, your section hike must start and end at least 50 miles beyond the limits of GSMNP.
But your Original Post suggests that you are ONLY hiking from Davenport to Fontana. That would required you to obtain a "General Backcountry" permit that requires reservations for all campsites and shelters.

If you are hiking on an AT thru hiker permit AND the shelter is full, you are allowed to use a hammock (the hammock may NOT be attached to any part of the shelter).
If you are hiking on a General Backcountry permit, you (in theory) have a reserved spot in the shelter, as those with AT thru hiker permits must surrender their spot in a shelter to those with reservations.

[HooKooDooKu]

Only half is uphill
You can be aggressive in second part
You can call and change reservations as you go too also, if you have Verizon service.
It's not as if it's all uphill to New Found Gap and then all downhill to Fontana.
I've done the hike between Silers and Spence in a day. While the distance is "only" 13 miles (a statement I couldn't have made 5 years ago), the series of ups and downs was a killer... especially since the worst of the climbs are towards the end of the day.

Again, it all goes back to your ability...
Without additional input from the OP, I can only assume that because the question is even being asked, the OP isn't like these AT thru hikers that can do 20+ mile days.

But I'll break it down like this...
A 4 night trip requires that you be able to do 15+ mpd along with thousands of fee of elevation change... every day.
A 5 night trip has been laid out above that can be done by those that can manage 12-13 mpd in mountainous terrain.
A 9 night trip is required if you can only manage a max of 10 mpd (due to the spacing of the shelters).
The only way to manage a 6 to 8 night trip is to do some days at 8-10 mpd and some days at 12+ mpd.
The trip is impossible without being able to do at least some 8+ mpd.

[MuddyWaters]

It's not as if it's all uphill to New Found Gap and then all downhill to Fontana.
I've done the hike between Silers and Spence in a day. While the distance is "only" 13 miles (a statement I couldn't have made 5 years ago), the series of ups and downs was a killer... especially since the worst of the climbs are towards the end of the day.

Again, it all goes back to your ability...
Without additional input from the OP, I can only assume that because the question is even being asked, the OP isn't like these AT thru hikers that can do 20+ mile days.

But I'll break it down like this...
A 4 night trip requires that you be able to do 15+ mpd along with thousands of fee of elevation change... every day.
A 5 night trip has been laid out above that can be done by those that can manage 12-13 mpd in mountainous terrain.
A 9 night trip is required if you can only manage a max of 10 mpd (due to the spacing of the shelters).
The only way to manage a 6 to 8 night trip is to do some days at 8-10 mpd and some days at 12+ mpd.
The trip is impossible without being able to do at least some 8+ mpd.

2/3 of the second half is essentially all downhill with small climbs
Rocky top to dericks is probably the roughest section in the park, regardless of direction. Mostly due to the rock steep trail that requires slow speed.

Mollies to Silers was a pretty long day uphill as I recall.

[daddytwosticks]

Two years ago, I decided to finally hike part of the park. Started at Clingman's Dome and went southbound to the dam. Don't remember where I stopped the first night, but I hiked maybe 11-12 miles. The second day southbound kicked my butt! I believe it was the part of the trail previously mentioned. I though southbound from the highest elevation of the park would be a cake walk. I was wrong. :)

[HooKooDooKu]

Mollies to Silers was a pretty long day uphill as I recall.
Mollies to Silers (which for those not keeping track is NOBO, but OP is going SOBO) is about an 18 mile stretch.
That section seems like it is all up-hill because you have to first make the nearly 1,500' climb from the low point between Mollies and Russle to the top of Thunder Head. Then you've also got the 1,000' net climb (with ups and downs along the way) from Sugartree gap to Silers.

But the other direction is no picnic. While things are mostly down hill between Silers and Derrick, you still have several uphill sections that are 100' to 300'. Once you get past Sugartree gap, then you've got a NET 1,000' climb to get to the top of Thunderhead, with a couple of extra 100'-300' up-down-up-down along the way. Then you've still got about an 800' climb to get to Mollies.

BTW, for those following along using the elevation profile (http://tnlandforms.us/at/gsmnpat.html), Thunderhead Mtn is the unlabeled peak between Spence and Derrick Knob. Sugartree gap is the lowest point near Derrick Knob.

[Yankee15]

I did this exact section as my first backpacking trip, ever! 8 days is a pretty easy schedule and was what I planned on...then it snowed 2 feet on Halloween and it took me ten...my advice is keep an eye on the weather because postholing through waist deep drifts while rationing food is not cool!!

[HooKooDooKu]

I did this exact section as my first backpacking trip, ever! 8 days is a pretty easy schedule and was what I planned on...then it snowed 2 feet on Halloween and it took me ten...my advice is keep an eye on the weather because postholing through waist deep drifts while rationing food is not cool!!

Yea, October can be an iffy month. I've seen permafrost in all the trees above 5,000 feet in October, and I've been sweating from the heat as well.

Seems like snow has been a rarity in October in recent years. But you can expect night-time lows to be around freezing along the ridge that time of year.