I have a half dozen or so umbrellas that vary in age and condition. They all do their job and keep the rain off my head while I walk.

The fabric on these umbrellas is not waterproof. I can easily suck air through it. If they once had a water repellent finish I assume it is long gone, particularly on the older ones. And most of them are fairly flat on the top when opened. They do slope downward of course but not at a very steep angle.

Why do they work? What keeps the rain moving toward the outside and off the umbrella instead of dripping through it? Could a similarly designed tent do the same without a waterproof coating? Inquiring mind wants to know.

The old school shelters made of canvas, silk and others were not waterproof and people dealt with it.

You had to be careful to not touch the walls. If you did you could create a wet spot.

People nowadays freak out from water inside their shelters and even complain because waterproof materials like silnylon, spinnaker and cuben aren't waterproof enough:-(

If you look at architecturally designed structures umbrellas are they are different shapes some are pointy and have steep wall like a yurt, Some are very flat dome shaped like a rock. So the shape is designed to shed rain. They also are are a very taut structure with quite a few ribs holding it taut so it will not develop sags that gather rain.

They have one thing in common is usually in the rain is the person is mobile and constantly moving and the wind is also blowing the rain off. When a object is mobile it does not gather as much rain as as a stationary object. Plus we also have the person holding it can change the angle attack of the umbrella tilting it one way or another in a few minutes and that affects how the rain sheds or slides off the umbrella.

So the problem I see with tents and other stationary shelters it impossible to design a tent that is constantly mobile and changes it angle of attack still stay taut through out the rain storm while we sleep.

The tepee design is the closest stationary type of structure that would shed rain with out moving but it would need more poles to keep it taut ,tepees also have to have a very large footprint in order for it to be usable to sleep in.
Terry

Edited by socal-nomad on 02/18/2012 09:45:30 MST.

You basically have a tent on a stick. And even a cotton tent will shed water if it is taunt.

Early umbrellas were made of silk and were said to get quite heavy when used in the rain.

Umbrella technology is so active that the US patent office employs 4 full time examiners for umbrella patents alone. There are over 3,000 active umbrella related patents in the US.

"There are over 3,000 active umbrella related patents in the US"

I did not know that.

Terry,

I never thought of the human involvement in the process. It would be like having someone monitoring my tent and making sure no water was pooling anywhere.

Daryl

I posit that umbrellas work as such do to a decided LACK of tautness within the entire system, as employed. Sure, the fabric may be stretched across the skeleton frame at varying degrees of tension, but that frame is fairly light and flexible. This "give" allows the force of each individual raindrop to be "taken up" by more parts in the system, besides the fabric itself. Providing even more dispersion of said force is the fact that you're holding the umbrella in your awesome, shock-absorby arm.

Compare this to a sheet of silnylon stretched nearly drum-taut across a set of relatively inflexible aluminum or carbon poles and guyed out with static lines, and I can see why one might experience "misting" with a tarp, while I've never even once noticed any misting under an umbrella...

Edit: Grammatical reasons only.

Edited by pillowthread on 02/18/2012 21:04:11 MST.

"There are over 3000 active umbrella related patents in the US".

I did not know that either; it worries me that I know that now.