PDA

View Full Version : Suggestions?



SGT Rock
2003-02-09, 15:25
Is there anything you would like to see me cover in the hammock pages on the site? If you haven't seen them yet, here they are: Hammock Camping (http://hikinghq.net/hammock/hammock.html).

I figure there are some things I'm taking for granted but someone wants to know. I has beeen a while since I added new material, so it is time to update. I'm just at a loss of what I should add.

titanium_hiker
2005-03-10, 16:31
you haven't tried a speer yet? a make your own is the best!
hello btw. titanium

SGT Rock
2005-03-10, 17:35
Not yet, but I would like to some day.

unbreakable
2005-03-10, 18:08
I have a question about hammocks. Since it's a suspended system, the hammock is below the tie off points; what prevents water from finding its way into the end of the hammock where the tie offs attach? I know on some tarps I have seen "rain rings" a smalletal ring that causes the water to collect and drop away before it reaches the bitter end. what method is used on these? Maybe you could do a piece on preventing water intrusion.

SGT Rock
2005-03-10, 18:46
On the HH, the line that suspends the tarp creats a point where the water drips off. If that isn't enough ou can always add a re-direct line.

bearbag hanger
2005-03-11, 00:54
Is there anything you would like to see me cover in the hammock pages on the site? If you haven't seen them yet, here they are: Hammock Camping (http://hikinghq.net/hammock/hammock.html).

I figure there are some things I'm taking for granted but someone wants to know. I has beeen a while since I added new material, so it is time to update. I'm just at a loss of what I should add.

After reading Turks description of the accident he had, it seems you should mention the tension a hammock puts on its supports. I don't remember where I read it, but when you have less than (I think) 45 degree angle between the support and the hammock lines, you are pulling more than the weight of the person in the hammock. Back when I first read it, I determined that I put about 600 to 650 pounds on each line, instead of the 90 pounds (half my weight) I thought I was putting on the lines. There is a mathmatical formula for figuring out what this force is, I just don't remember what it was.

youngblood
2005-03-11, 07:24
After reading Turks description of the accident he had, it seems you should mention the tension a hammock puts on its supports. I don't remember where I read it, but when you have less than (I think) 45 degree angle between the support and the hammock lines, you are pulling more than the weight of the person in the hammock. Back when I first read it, I determined that I put about 600 to 650 pounds on each line, instead of the 90 pounds (half my weight) I thought I was putting on the lines. There is a mathmatical formula for figuring out what this force is, I just don't remember what it was.I like that idea. The equation is pretty simple, I've put it into a spreadsheet and seen where others have also but I think it should be in a lot of convient locations for hammock folks so that everyone gets the message. The other problem Turk may have had is where he tied off to the door in relation to where the door & frame where secured to the wall... he may have gotten a little mechanical advantage in the form of a lever arm from that as well. That was a nasty situation... someone posted on Whiteblaze.net one time about tying off a hammock to a shelter and having the post move when they got in the hammock.

Youngblood

SGT Rock
2005-03-11, 07:27
Now that is something worth noting

SGT Rock
2005-03-11, 09:44
Hey, can someone send me the math on that?

youngblood
2005-03-11, 10:29
Sarge, the force on each hammock rope is:

Force = ( occupants weight/2 ) / ( sin ( rope angle ref. to the horizon)).

There is a spreadsheet here with a diagram and the equations: http://tinyurl.com/3thvr ... all you are interested in is Force1, Angle1 and Weight. Feel free to do what you like with the spreadsheet. It might be more helpful to folks to just list a multiplication factor table with a good diagram, maybe something like this?:

For this rope Angle ===> Multiply your weight by this number

30 ................................ 1
15 ................................ 2
10 ................................ 3
7 ................................ 4
6 ................................ 5
3 ................................ 10

You can probably do a better job of that than I can... I sometimes get to involved in the details for most folks and this shouldn't be complicated. If I can help you out, just let me know.

Youngblood

SGT Rock
2005-03-11, 10:33
Sarge, the force on each hammock rope is:

Force = ( occupants weight/2 ) / ( sin ( rope angle ref. to the horizon)).

There is a spreadsheet here with a diagram and the equations: http://tinyurl.com/55rcq ... all you are interested in is Force1, Angle1 and Weight. Feel free to do what you like with the spreadsheet. It might be more helpful to folks to just list a multiplication factor table with a good diagram, maybe something like this?:

For this rope Angle ===> Multiply your weight by this number

30 ................................ 1
15 ................................ 2
10 ................................ 3
7 ................................ 4
6 ................................ 5
3 ................................ 10

You can probably do a better job of that than I can... I sometimes get to involved in the details for most folks and this shouldn't be complicated. If I can help you out, just let me know.

Youngblood

So if I get an angle that is only 3 degrees of horizontal, then I have 10 time half my body weight? Am I reading that right? If I am, then the greater the down angle, the less force is being aplied on the support structure?

IE: 166 pounds/2 = 83 pounds. At only 3 degrees, then the stress on each support is 830 pounds.

bearbag hanger
2005-03-11, 11:13
So if I get an angle that is only 3 degrees of horizontal, then I have 10 time half my body weight? Am I reading that right? If I am, then the greater the down angle, the less force is being aplied on the support structure?

IE: 166 pounds/2 = 83 pounds. At only 3 degrees, then the stress on each support is 830 pounds.
Darn, you all found the formula before I did. Anyway, it helps to have a fancy HP calculator for this.

force = (166/2) / (sin(3.0))
force = 83/.052336
force = 1,585 lbs

But, it's remarkably hard to get a 3 degree setting on the lines, no matter how hard you pull on the lines when setting up. My eyeball shows about the best I can do is about 7.5 degress once I get inside the hammock.

force = (166/2) / (sin(7.5))
force = 83 / .130525
force = 635 lbs per line (1,270 lbs total)

Which is why Hennessey uses 1,450 lbs test lines on his lightest hammocks. There is a slight limitation to the formula. If you should reach 0 degrees, then the force is infinite. It's possible I'm not doing it right.

SGT Rock
2005-03-11, 11:19
Hey, I can't get that shortened link to open. Can I get the full link address?

youngblood
2005-03-11, 11:36
Actual 3 degrees is 10 times your full body weight, not half your body weight.

I did some rounding off... didn't know you were going to get the calculator out. 1X is 30.000, 2X is 14.478, 3X is 9.594, 4X is 7.181, 5X is 5.739 and 10X is 2.866. If you re-arrange the equation you can solve the angle that relates to any particular multiple of force to weight. The caver's are experts with all this, especially the rescuers's that have to rig up litter's and such to haul folks out. That is where I found some of the info.

And yes it does go to infinity at 0 degrees. If you pull your hammock taut and then get in... something has to give, it can't stay too close to 0 degrees when significant weight is applied. Try putting some weight on the middle of a line and then pulling it taut, you'll see how it works. It is kind of fasinating thought, it caught me by surprise until Rick (aka Risk, FlyFisher) brought it up a couple of years ago and Ed Speer mentioned to me that some cavers had said something about it to him. It's just not intuitively obvious when you are using a limp rope.

Youngblood

youngblood
2005-03-11, 11:44
Hey, I can't get that shortened link to open. Can I get the full link address?I don't know what is going on with that, it worked for a minute and then it didn't, so I went back and did it again and the same thing has happened. It is in the files section of yahoo's hammockcamping group under Youngblood. This is the link: http://groups.yahoo.com/group/hammockcamping/files/Youngblood%27s/ .

Lanthar
2005-03-11, 11:55
Actual 3 degrees is 10 times your full body weight, not half your body weight.

And yes it does go to infinity at 0 degrees. If you pull your hammock taut and then get in... something has to give, it can't stay too close to 0 degrees when significant weight is applied. Try putting some weight on the middle of a line and then pulling it taut, you'll see how it works. It is kind of fasinating thought, it caught me by surprise until Rick (aka Risk, FlyFisher) brought it up a couple of years ago and Ed Speer mentioned to me that some cavers had said something about it to him. It's just not intuitively obvious when you are using a limp rope.

Youngblood

This is why you can never get a rope with no load to actually tighten to 0 degrees... it would require infinite force.

peter_pan
2005-03-11, 12:49
Rock,

Adding Jacks R Better to your hammocks links and possibly your hammock equipment tests to the hammock section would be nice ...but then I'm biased.

Pan

SGT Rock
2005-03-11, 15:31
Rock,

Adding Jacks R Better to your hammocks links and possibly your hammock equipment tests to the hammock section would be nice ...but then I'm biased.

Pan

You may be bias, but it is a good idea.

GregH
2005-03-11, 17:41
So if I hang my hammock like a big "U" I'll be putting very little stress on the tie-points, correct?
(Of course, sleeping in a big "U" wouldn't be very comfortable.)

Lanthar
2005-03-11, 18:10
So if I hang my hammock like a big "U" I'll be putting very little stress on the tie-points, correct?
(Of course, sleeping in a big "U" wouldn't be very comfortable.)
exactamundo...

Mutinousdoug
2005-03-11, 18:23
GregH

if I hang my hammock like a big "U" I'll be putting very little stress on the tie-points, correct?

That's right. the closer you pull the rope in the vertical vector (direction of gravitational pull), the more you limit stress to your body weight.
Remember though, if you tie off really close to the ground, you can get your hammock to hang almost horizonal.

Dang! Lanthar beat me to it.

titanium_hiker
2005-03-12, 09:54
what about a link to the hammock wiki? http://www.imrisk.com/cgi-bin/hwiki.pl
it will only get better if more people contribute to it.

SGT Rock
2005-03-14, 13:12
A link to that is also a good idea.

SGT Rock
2005-03-15, 11:14
Don't you just hate it when you are in the middle of a document and loose power.

Sometimes things suck :(

youngblood
2005-03-15, 12:07
Don't you just hate it when you are in the middle of a document and loose power.

Sometimes things suck :(Yeah... then I think about a UPS (no, no, not the delivery folks, a battery backup, an uninterupted power supply). Then I think about it some more and decide to just backup what I am working on more often. That usually gets me through the urge to go spend more money on none hiking things. I figure as long as the frequency of painful interupts is longer than the frequency of... uhh... uhh . Never mind.

Youngblood

Just Jeff
2005-03-15, 12:31
I didn't realize how nice an UPS was until I got one. I used to be careful of working on stuff if it was storming outside because I didn't want to lose anything. Now I don't care if the power goes out or not! An UPS also "smooths out" the power supply, providing your computer a "healthier diet" of electricity...supposed to be better in the long run.

My question: How does a ridgeline interact with the force on the hammock supports? If the supports are each pulling with 1000lbs of force, is all of this force transferred to the ridgeline? And if it's 1000lbs on each support, why isn't the the stress on the ridgeline 2000lbs?

Jeff

SGT Rock
2005-03-15, 12:41
The power problem for me is the power supply going bad. If I touch the computer when the planets are in some sort of special alignment, then I lose power. Otherwise I could beat it with a bat and not lose power. I often think I have the problem licked and it gets me like it did today in the middle of cutting, pasting, updating, and fixing web pages! :(

As to the stress on the ridge line of the hammock - I assume you mean the part under the net. I imagine it would EXCEPT that when you get in the hammock, the ridge line is now in the part with no stress since the middle sags. The knots and tree huggers now must support 450 - 1700+ pound each (depending on the angle).

blackdog
2005-03-15, 12:50
A laptop has the UPS built in. I just love it.

Just Jeff
2005-03-15, 14:02
I guess a lot of the force is transfered to the hammock and along the supports when you climb in. It probably also depends on how much your ridgeline shortens the overall length of the hammock when occupied. My WarmHammock had quite a bit of sag compared to the HH, and I think the ridgeline was a lot tighter than the HH, meaning it was probably withstanding more force.

I was just wondering how small I could go with the ridgeline cord and still be safe. I have some very small (2-3mm) non-cored Spectra that I was considering. Just a bit smaller than what's on the BP A-Sym.

youngblood
2005-03-15, 16:34
...As to the stress on the ridge line of the hammock - I assume you mean the part under the net. I imagine it would EXCEPT that when you get in the hammock, the ridge line is now in the part with no stress since the middle sags. ...Sarge,

While it is true that when you get in the hammock there is no vertical force on the ridgeline, the horizontal force on the ridgeline is the difference between the horizontal force on the hammock support rope and the horizontal force on the hammock fabric itself... doubled, since the same thing is happening on both ends. So it is a function of the weight and the angle of the hammock versus the angle of the hammock support ropes.

I would suggest the following experiment: Set up a hammock (this is easier to perform with an open top hammock), tie additional ropes from each hammock where the hammock fabric attaches to the hammock support rope, hold each rope in separate hands, sit in the hammock and try to do a 'hammock curl' with the ropes to raise the hammock. If there is no stress on this 'ridgeline', you should be able to raise yourself very easily by shortening the 'ridgeline' when you do a 'hammock curl'. If you're a weak old man like me... you will notice that there is some resistance-- actually I think a strong old man like Chuck Norris would notice the resistance :) . Alternately, you could pull the hammock ends together with the additional ropes before you sit down on the hammock and see if you can maintain that 'ridgeline distance' when you apply your weight by sitting down on the hammock.

Youngblood

SGT Rock
2005-03-15, 16:51
Well maybe we are talking about some other force or point, but often notice slack in my HH ridge line after I get in.

SGT Rock
2005-03-15, 19:57
Sorry about the site going down there for a while. The hosting company upgraded something which totally screwed FrontPAge server extensions which resulted in some forum stuff getting jacked up. :cguru: