DIY Modding my HH Exped for winter hanging

[OutandBack]

Hi Guys,
I decided to mod one of my HH Exped hammocks that has the second bottom layer for winter camping. Being short on funds this year, with the holidays coming, my goal was to make this hammock the warmest I could with existing equipment on hand.

Step 1 was to remove the netting so the hammock could be entered from the top.
I usually get into my sleeping bag by standing beside the hammock and pulling the bag on like a pair of pants. Then setting down in the hammock and swinging my legs over.

Hammock Testing Area


Step 2 was to close the bottom entry. I untied the elastic shock cord and installed snaps.
This allowed the 2nd layer to lay/hang more evenly contoured to the bottom of the hammock.



Step 3 was to install snaps so I could use my summer sleeping bag as a UQ. The snaps hold the bag in place to keep it from shifting.






Step 4 was to remove the mitten clips that were supplied with the 2nd bottom layer and moving the attachment up to the original attachments for the tarp. By using the sliding knot I can adjust the distance the 2nd layer is to the bottom of the hammock so the UQ is not compressed under my weight when in the hammock.



I slept in this last night. It got down to 14F and I was toasty warm.

Comments, questions, suggestions all welcome.

Thanks for looking…

[Poppabear]

I would say that you have done your self proud. The litmus test for any mod is to use it. "14F and I was toasty warm" just about say's it all. Congrats!

[rjcress]

Nice.

Sorry, but I'm not following the "second layer" that you mentioned.
In the last pic it looks like you have a hammock sock hooked up to the prussic. Is that right?
I'm really interested in understanding how you insulated the bottom, as 14F is pretty impressive without a pad or UQ.
I think I must be missing something.

[OutandBack]

Nice.

Sorry, but I'm not following the "second layer" that you mentioned.
In the last pic it looks like you have a hammock sock hooked up to the prussic. Is that right?

HH sells a winter kit which has a second layer of nylon for the bottom of the hammock. They also provide light open celled foam pad which lays between the hammock and this second layer. I just replaced the foam with a summer sleeping bag. Holding the bag in place with snaps. This second layer or sock as you call it is attached to the prussic knots which allows me to adjust the distance between the hammock and second layer. In picture 3 you can see the SB laying in the second layer/sock. The hammock has been lifted out for the shot.

Clear as mud? Sorry I don't know how else to explain it.

I'm really interested in understanding how you insulated the bottom, as 14F is pretty impressive without a pad or UQ.
I think I must be missing something.

The total thickness of the summer sleeping bag is 3.5" that bag is my UQ just held in place by the sock/ 2nd layer.

My TQ is a North Face -5F down mummy bag zip up all the way.
Other insulation; heavy wool socks, poly sweatpants, 100 microfleece LS top, silk head cover with wool watchmans cap, smartwool glove liners.

Thanks for the comments and the questions.
hth

[Knotty]

If the second layer is a Hennessy SuperShelter, then you're may well run into condensation problems. The SS is silnylon, so it doesn't breath. That's not too much of a problem when using the Hennessy open cell foam pad, since you can squeeze the water out, but a sleeping bag won't be so forgiving.

Last night I tried something similar, using a KAQ primaloft underquilt inside a SS. Conditions were as bad as can be for condensation with temps starting in the high 20's and then rising into the 30's with heavy rain and high humidity. By morning my KAQ was soaked, but I did stay warm. Had I used a down underquilt it would have been a very uncomfortable night.

[Knotty]

Forgot to mention that I did use a space blanket between the hammock and KAQ.

Pics:

[OutandBack]

If the second layer is a Hennessy SuperShelter, then you're may well run into condensation problems. The SS is silnylon, so it doesn't breath. That's not too much of a problem when using the Hennessy open cell foam pad, since you can squeeze the water out, but a sleeping bag won't be so forgiving.

Last night I tried something similar, using a KAQ primaloft underquilt inside a SS. Conditions were as bad as can be for condensation with temps starting in the high 20's and then rising into the 30's with heavy rain and high humidity. By morning my KAQ was soaked, but I did stay warm. Had I used a down underquilt it would have been a very uncomfortable night.

Hi Ron,
Thanks for the info. I need to check the HH website and see what this second layer is called. That might help in my write up.
The material does has a sheen to it and it is not as thick as the hammock material. It very well could be water proof.

When I woke this morning about 7AM I did check the lower bag to see if it had shifted. I did not notice any condensation on the bottom of the hammock or when I was moving the bag around. However some could have been there.
I didn't remove the bag because I'm going out again tonight to try a different sleeping bag. My -5 down mummy is very tight around the shoulder if I have to keep my arms inside. I want to try my car camping syn bag (rated at +10F) which is more box shaped. For winter car hanging/camping this bag would be much more comfortable to just hang around in. IF it will keep me warm. I'll find out in about 3 hours.

[Knotty]

Based on your pics, I'd say that's definitely a SS.

[BillyBob58]

HH sells a winter kit which has a second layer of nylon for the bottom of the hammock. .........

So the 2nd bottom layer is the HH SS undercover? Anyway, some pretty ingenious mods there! But you did not have a vapor barrior/space blanket on top of the bag, right? If so, I am surprised you had no condensation in the under bag.

Forgot to mention that I did use a space blanket between the hammock and KAQ.

Pics:

You used a sp.blanket covering over the KAQ, and it was still soaked? Well, here we go again! I can't figure out why I have never had this happen after 3 years of using the SS on and off. From the super high humidity 50s down into the teens. With down and fleece some times under the HH OCF pad.Never a drop as long as I used the Sp.blanket.
(Or, a space blanket in a PeaPod down to 10, dry as a bone.) I must just be over due!

I suppose the only explanation is the one Youngblood put forth. Some how, vapor that is already in the air space below the hammock and sb, and maybe in the insulation, condenses on the cold sil-nylon. It seems like a stretch to me, at least for there to be enough water vapor to soak insulation. I suppose a fresh supply of vapor could rush in when a person moves. But, this air would already be maximally cold, so why would the humidity it contains keep on condensing against the inner layer of the UC which is no colder than the air? Oh sweet mystery of life!

But even harder to understand is: I don't see how vapor from the user can get past a waterproof space blanket or vapor barrier to condense in the KAQ. so I guess something like the above is the explanation?

[OutandBack]

So the 2nd bottom layer is the HH SS undercover? Anyway, some pretty ingenious mods there! But you did not have a vapor barrior/space blanket on top of the bag, right? If so, I am surprised you had no condensation in the under bag.

Thanks for the comments BB58,
I did not use any kind of vapor barrier. Since I'm going back in the hammock tonight with a different sleeping bag I will really check the bottom sleeping bag for condensation. I really don't want to use a vapor barrier unless I really have to.
I am not sure if this matters but I live in Colorado and the humidity last night was about 15%

On Ron's issue. I can't see how sweat could get thru a SB / VB either. the water had to come from some other source. like running down the hammock line? He did say it was raining.