View Full Version : dew under the rainfly? add a fly ridge?
volks-man
09-06-2009, 10:04
couple nights ago i was hanging in the hennessy ULB at home. i awoke to some condensation on the inside of the stock rainfly wich was wetting the bugnet that it had sagged down and touched.
i made up the sligshot tensioners for the rainfly-to-support-line connection and hung 2-3lb weighted meshbags from the fly tie-out biners to self adjust.
last night i never made it back outside but had left the hh set up. this morning i found that dew had formed on the inside of the rainly and that it again had touched the bugnet and started dripping in to the hammock.
anyone else having dew on the inside? bear in mind the second night i was not in the hammock!
though, i have read about tying the fly to the trees instead of the hh adjusters, would it help instead to add a ridgeline to the fly to keep it and the underside dew away from the net? perhaps a through-cord tied to both trees that the fly floats on with the stock flimsy hooks and tensioned by hh style sliding knots?
any input appreciated!
Dew does what dew wants to do. Dew does what dew wants to do. Dew does what dew wants to do...
There really isn't anything you can dew about it. Well maybe hike in Arizona. Hanging your tarp higher will help. You'll be getting dew on the bugnet, uq, and hammock and everything else. But it's just dew. You could get a hammock hut and that will work if condensation doesn't become a problem.
Welcome to the forum Volks
volks-man
09-06-2009, 10:37
Dew does what dew wants to do. Dew does what dew wants to do. Dew does what dew wants to do...
There really isn't anything you can dew about it. Well maybe hike in Arizona. Hanging your tarp higher will help. You'll be getting dew on the bugnet, uq, and hammock and everything else. But it's just dew. You could get a hammock hut and that will work if condensation doesn't become a problem.
Welcome to the forum Volks
thanks.:)
yes dew does..... was thinking not just hanging the tarp higher but much tighter would help the dew run down the fly rather than run down/drip on the bug net. maybe pulling a very taught 'frozen rope' for a fly-ridgeline then simply using the hh style slides perhaps in conjunction with my slingshot tensioners......
but, dew does as dew does.
Just Jeff
09-06-2009, 10:46
The condensation under your tarp could be from a few different things, like your breathing (but not while you weren't under there), moisture rising from the wet ground/grass, or fog (even if you can't see the fog there can still be moisture condensing around you). Because of radiation, your tarp gets cooler overnight and can cause the moisture to condense on it (not the falling dew most people are familiar with). Ventilation can help (pitch it so the wind blow thru it). Even your body heat can help, if your breath doesn't make up for it.
Regardless, when it's humid outside you're gonna have condensation somewhere.
I don't think a ridgeline under the tarp would help. I think it would be worse, b/c if it's raining the line can cause water to seep thru where the ridgeline contacts the silnylon. I would tie the tarp to the tree separately from the hammock (so I could set up the tarp in the rain, then unpack under it) and that should go a long way to keep it from sagging.
volks-man
09-06-2009, 11:25
thanks jeff..........
for both the post and your slingshot tensioners!
Just Jeff
09-06-2009, 16:22
No problem - glad to help.
volks-man
09-07-2009, 17:46
heres the skinny on the rainfly.
i sent an email to hennessyhammocks this morning reporting my troubles and asking for any tips or assistance they could offer. shortly thereafter i received a reply from hennessyhammocks asking for a phone number and time i'd be available for a call. shortly after i replied, Tom Hennessey called me personally to sort things out.
Tom advised me to tie a cord to one end ring on the fly, wrap the first tree, return to that first ring and run through it continuing under the fly to the ring on the far end, run through the second ring, wrap the second tree, and back to the second ring. by running the cord through the second ring and back toward second tree you can use a prussic on the cord to tension the whole works. (paraphrased) this is the method that he uses personally and stressed the ability to set up the hammock dry under the fly. he also mentioned that dew on the underside of the fly is not a big problem if the fly is taut and steep enough.
while discussing rainflys Tom advised me that, as hammocking is an evolutionary activity, Hennessy will soon be packaging caternary cut rainflys with their hammocks!
through each email and our phone conversation Mr. Hennessy was nothing but polite, helpful, and even greatful for all the word-of-mouth sales from us 'hangers'.
thanks for all your help and suggestions on here on HF!
Just Jeff
09-07-2009, 18:08
Glad you found (hopefully) a solution to your problem.
Cat tarps are already on his website. Wonder how long it'll be until Tom starts making half-underquilts.
Just wanted to chime in that I had my hammock up for a couple of humid days this August and each night as the temps dropped the tarp became coated on both sides with dew. Oddly the hammock showed no moisture. This all happened while the hammock was vacant.
Mustardman
09-08-2009, 08:12
Wonder how long it'll be until Tom starts making half-underquilts.
Wonder how long it will be till he patents them :lol:
Opps, did I just type that out loud???? :scared:;)
Just Jeff
09-08-2009, 21:47
He waited a hundred years or so to patent the structural ridgeline...
Alright...I'm gonna stop so this doesn't turn ugly. Back on topic for me. :jj:
While hanging with Kayaknut on an overnighter we both were using MacCat Deluxes. His was Spinn and mine is Silnylon. Dew had collected on both sides of mine and his was almost dry. Spinn is by far better in weight and water retention. The Sil is fine, but you have to hang the tarp up high enough not to rub on it. The weather was calm, no rain and in the 60's.
So does anyone know why two tarps of different materials in the same place would produce different results?
The silnylon tarp getting coated on both sides can't be due to leaking, right?
Mustardman
09-09-2009, 08:49
So does anyone know why two tarps of different materials in the same place would produce different results?
This is a purely hypothetical conjecture, backed up neither by personal experience nor collected data. Gigantic grain of salt, here....
My guess would be that spinntex is more hydrophobic than silnylon, which on the surface seems like a logical guess - spinn doesn't soak up water and get heavy like sil tends to after a hard rain.
So, if spinn is more hydrophobic, it's less likely to collect condensation.
Just Jeff
09-09-2009, 17:58
I would say it has to do with the rate of radiative heat loss...which is one of the things that causes humidity to condense on objects (especially the undersides). Falling dew is only one kind...and it only coats the tops. I forgot the real name of the other dew...sometimes called rising dew...but it condenses onto cooling objects from humidity in the air, because sometimes radiative heat loss makes that object cool to below the dewpoint faster than the surrounding air temp.
Or so I understand, at least... :jj:
There was a lot of dew and moisture in the air. It didn't seem like the material was leaking. During a rainstorm it seemed even drier than that morning, if that's possible. I notice it a lot because when I make a run at night I'm always careful not to get my back wet. My next tarp will be made of Spinn if not for any other reason than staying drier.
volks-man
09-15-2009, 19:33
last week i was in central jersey during the torrential downpours. i stayed out in the hammock for quite a while in some of the heaviest rain on wed night.
the tiny HH fly with custom ridgeline worked wonderfully!!! not a drop in or on the hammock. the fly was pitched very taut and very steep for the rain. guess i got lucky as it was only my first try sleeping in a substantial rain.
i only came back in the house when i realized, after laying there for hours, that the rain was so loud on the fly that i could not sleep! in the morning the hammock was still dry.
the only real problem with the way mr. H told me to set up the fly is the added complexity/set-up time.
i think that with a little time and some better cord i can perfect this setup!
I have less experience than most, but on the few nights I've slept in heavy rain in my HH with the stock fly I never got wet. Looking forward to trying this new method though.
I would have thought with all the gram weenies we have here the minimalist approach of the HH tarp would be more popular.
volks-man
09-16-2009, 00:04
I have less experience than most, but on the few nights I've slept in heavy rain in my HH with the stock fly I never got wet. Looking forward to trying this new method though.
I would have thought with all the gram weenies we have here the minimalist approach of the HH tarp would be more popular.
the method:
i made a mistake using the wal-mart imitation paracord. it stretched far too much. don't make the same mistake i did!!!! :) also, i think that i could pull a tighter ridge with the fly rings floating on the new ridge and using prussics to tension either end. i think there may be a limitation to pulling the fly and the ridge taut in one motion as HH suggests. if i ever use the proper cord i will be able to tell for sure. this also greatly simplifies moving the fly after it is set up over the hannock for better coverage on one end or the other. with one cord looped around all the rings and trees the fly is a bear to adjust, end to end.
the weenies:
i am more of a 'pound' or maybe even 'ounce weenie'. i got the HH UBA because of the weight..... i am not pleased about having to carry the extra weight of the cord. hopefully i will find (or someone here will suggest) a lightweight 1/4 cord, thats light, strong, non tangling, and non stretching!