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Simva2020
2003-01-18, 06:45
give us periodic reviews/pointers as you go through Speers book....
dont make us wait until you have read all of it please.

CanoeBlue
2003-01-18, 08:03
I have both read the book and I have chatted at some length with Ed Speer and will probably post a review of the book this weekend in the book section of this forum.

Before I read the book I was convinced that the insulation should go on the OUTSIDE of the hammock and after Reading the book and chatting with Ed I am more convinced than ever. I notice that you are working on an underquilt and I have no question that is the way to go, though I wonder about the use of Silnylon because of condensation issues.

I too, am working on an underquilt - I started out designing it for Thinsulate 200 (warmer than primaloft but not as bulky)- but when it came I felt that it was going to be too heavy so now I am working with down.

I like making my own gear because it means that I can make it the way that I want it, and I have either made or at least modified made most of the gear that I use. Most gear is pretty simple really, or at least should be, but making something like the Hennessey Hammock would be WAY beyond my capabilities. The Speer hammock system, however, is very simple and just about anybody could make their own camping hammock system from the instructions that he gives in the book.

Simva2020
2003-01-20, 07:25
most of the sleepers moisture rises up with heat from the body and through his/her breath during exhalation.
a certain amount is created and momentarily trapped beneath the sleeper. This condensate must pass through sleep clothes if worn, a sleeping bag if used and then the hammock material before it can reach the underquilt...in my underquilt the condensation will have to pass through aluminized sil-nyl before it can enter the insulation (Primaloft is my choice and it cannot absorb much moisture if at all)...
so the issue of condensation entering the insulation of the underquilt is of little debat in my mind. Further lessening the impact is my use of a VBL in my sleeping bag for several reasons:
1. less moisture in my bag
2. less moisture to condense in my tent or hammock (especially after the Pertex panels are placed over the bug netting for cold weather use
3. a more hydrated 'me' after sleep

There is the possibility of cold air hitting a warm surface-i.e. between the top surface of the underquilt and the bottom of the hammock proper....this will reflect on how well the underquilt fits the occupied hammock, therefore I would stress that the measurements be taken while occupying the hammock, and that a differential cut by applied to the top and bottom surfaces of the underquilt to rule out cold spots where condensatin is more prone to occur

The sil-nyl on the bottom surface of the underquilt is to assure that the insulation is not wetted by 'splash' rain

The top surface of the underquilt is still in debate. I know I want a reflective material but Warmlite wants 25$/yard for aluminized sil-nyl whereas the Adventure Medical Blanket was 1/8 the total price. I am exploring options such as Quest Fabrics to see if I can get the aluminized sil-nyl at a cheaper rate.

Dont forget to explore the 'under-cone' under the hammock....this can be done with any waterproof fabric and simple extends from where the netting meets the hammock toward the ground, with each side coming together to form a point giving it a cone shape in a profile view. It need not go to the ground and we have debated the merits of this many times-weather vaning versus ground temp advantage-and decided that simply creating a dead air space under the hammock that isnt constantly robbed of heat by the wind is a decided advantage-along with creating a place for boots,pack, extra gear,etc. In fact the extra gear gives the under-cone ballast to help hold is shape.
The under-cone is a best attempt at what in a perfect world would be panels on each side draping all the way to the ground, but since when setting up a hammock you never know exactly where the ground is we thought a pocket of dead space would be better than nothing, where the two panels come together they velcro and that slit is in line with the entry slit of the HH.

Hey, have you heard mention lately of the singel point hammocks? Evidently they are used by climbers on long belays,,,,one rope coming down and then splitting off into 6 attaching points for a stretcher like hammock.....now the cool thing about this setup is that it will turn into the wind (weathercocking us sea kayakers call it) and let much of the force of the wind pass by.....something to think about though I dont think camping in the woods would allow it.

Also something else to explore, the ceremic paints now used in the housing industry...a thin film of paint is giving homes additional R values of up to 12points...not bad for something that thin...I just cant find out if they are flexible enough after curing to go in and out of a stuff bag.
Ok enough for now.
Later
sim-hiker

Yedi
2003-01-27, 19:56
I asked about this a while ago on the old forum. I see that you use a vapor barrier in your hammock. Have you had good results with this? Do you get much more warmth, or is it simply a matter of keeping your bag dry that you use it? Thanks.