@melenas said:
He did not mention an elephant sitting on his head.
No one ever mentions the elephant.
@Guideboatguy said:
@melenas said:
He did not mention an elephant sitting on his head.No one ever mentions the elephant.
Even if it’s in the room.
Regarding water permeating the tent walls vs that moisture being actually condensation that occurs due to temperature differential: I owned and heavily used two different Cannondale tents during the 70’s and 80’s when I was an avid year round backpacker and outfitter guide. One of the unique design features of Cannondale tents was that they did not use waterproofed material for the tent roof fly or side walls, only the floor. The tents pitched very tautly with an inside wall and outside fly separated by about 3 to 4" of consistent air gap.
What Cannondale had discovered in the design phase was that rain would mostly run off the outside wall (think of nylon umbrellas, which are not made of waterproof material) though the material would also absorb water and become wet. But the water that leaked through would run down the inside of the fly rather than drip onto the inside wall. Meanwhile, because the air gap created a sort of insulating zone (the fly went all the way to the ground) and the inner wall was completely breathable, water vapor from the exhalations of the tent inhabitants passed through the inner wall without condensing on it. That vapor could also pass through the outer wall on dry nights, or, if the temperature differential caused it to condense on the inner surface of the fly, it would be absorbed rather than create droplets that could fall onto the inner wall.
Nonsensical as it may sound, these were absolutely the driest tents I ever used, year round. And I have owned tents from multiple manufacturers, including North Face, Sierra Designs, REI and Marmot, and often shared tents of every other major brand with my backpacking companions. I used the Cannondales quite often in the winter and never had any frost on the inside walls (which I always got with other conventional waterproof fly tents) which illustrates that condensation was not occurring. They had huge floor-less vestibules which were great for cooking in bad weather and for storing muddy or damp gear outside the sleeping zone.
As for rain, used one in a pouring 10 hour deluge on Assateague Island and slept like a baby on several nights when everyone else was kept awake by the flapping and snapping of their tent flies in the gusting winds – my Cannondale was not only dry inside but completely silent as well. I had banked sand over the bottom of the outer fly and the tension of the frame and aerodynamic shape of the tent kept the wind from getting under the nylon. The outer fly was soaking wet in the morning when it rained but as the weather cleared and the sun came out the nylon quickly dried. Uncoated nylon is breathable so air passing through it creates rapid drying.
I still have one of the Cannondales – they stopped making them in the 80’s and just stuck to bicycles henceforth. The only drawback for backpacking was that they were heavy (7 to 8.5 pounds for a tent that held two comfortably or 3 in a pinch) but I’ve used that one for car camping within the past couple of decades. Despite being 40 years old, it’s still usable since there is no waterproofing issue with the fly. The coated floor is probably not waterproof any more, but since I always use a tailored ground cloth, that shouldn’t be a big deal.
Another bit of more common evidence that the moisture on the inside of your tent walls is generated from the inside and not from outside is the fact that tents with mosquito netting walls (like my summer weight Marmot) don’t cause you to get wet when it rains on the outer waterproof fly. If the fly was actually allowing water to penetrate, it would be falling through the mesh. Instead, because the mesh is completely breathable and there is no temperature differential on either side of the fabric, no condensation occurs there. It may condense on the inside of the fly, though the free circulation of air in the space between tent wall and fly will keep that to a minimum. Last used that Marmot during a dusk to dawn monsoon at Flamingo in the Everglades. We barely got the tent up as the storm began but slept completely dry – zero condensation – despite near 100% humidity.
As to the leaking tarp, having a pool of water collecting ABOVE the tarp creates water pressure. The upper layers of water are causing more PSI pressure at the bottom, just as depth in a lake or ocean creates higher PSI. When your dry bags are sitting in water they are NOT creating higher pressure at the point of contact because, unless they are trapped in a vacuum, the water is free to flow out from under the weight of the bags. The same is true of wet ground below your tent. Water equalizes its own level. There may be more water pressure on the bag around the sides of it if the bilge is deep, but the weight of the bag itself is not causing more pressure beneath itself, nor is the tent.
That said, the Achilles heel of most “dry” bags is generally the seams and closures, not the material itself.
I wonder if anyone has tried those vacuum evacuation clear plastic clothing and bedding storage giant ziplock bags for canoe pack liners? They are airtight enough to maintain a vacuum for extended periods so they should be able to resist penetration of water. And they are cheap – I’ve gotten 3 packs of several sizes for under $10 at places like Marshall’s. Trapping air inside one rather than evacuating it would maintain some pressure that ought to help keep water from seeping in (a vacuum would just encourage moisture entry). They do make kayak flotation bags that can be used to store gear in the inflation chamber. You load the bag, seal the opening and then inflate through a valve.