# Thread: Bridge Hammock

1. Originally Posted by schrochem
Tee Dee,
I need some help with the ends. I am making end pieces for the bugnetting and it's the same shape as your draft stopper.
It seems to me that it is diamond shape with the bottom two sides of the diamond are longer by about 20% than the top two sides. That bottom 'point' will be rounded off...
Or are you just making a triangle on top with a rounded bottom....?
Thanks
When I made the draft stopper, I just plunged ahead and used clothes pins and tucks to make the draft stoppers fit. I ended up with extra material even though the fit is pretty good.

I now know a much easier way to make the draft stopper (which I will be using on the final draft stoppers) and maybe you can extend or adapt my technique to your use:

1. measure the distance from ridge line to the straight line connecting corner ring to corner ring (or just use the distance to the spreader bar which will probably be pretty close to the same thing) with hammock empty. This distance will be smaller when you get into the hammock, at least mine is since my spreader bars swing up towards the ridge line when I get in - the forces on the arc cut webbing guarantee that. So measure when empty as that will be the longer measure which you have to fit. Since you know the spreader bar length or the distance from corner ring to corner ring, that gives you the dimensions of the triangular shape from the corner rings to the ridge line. That part is then easy to fit, just allow for hems or bias tape whichever you use.

2. You already know the length of the fabric from corner to corner on the side of the hammock, call this length p/2 (see below), so you know the length of the bottom edge of the fabric for the side piece and all you really need is the shape. The easiest way to fit the needed shape is to use either a circle or ellipse. The ellipse will fit the shape of the hammock when occupied better than the circle, so make an ellipse with the required arc length from semi-minor axis to semi-minor axis - you know the length of the semi-minor axis already - 1/2 the distance from corner ring to corner ring, so all you need is the length of the semi-major axis which is given approximately by:

a**2 = ((p/pi)**2)/2 - b**2

where:

a == length of semi-major axis == distance from straight line connecting corner rings to bottom of hammock fabric,
p == circumference of ellipse, or twice the length of the hammock fabric from corner to corner,
b = length of semi-minor axis == 1/2 corner ring to corner ring distance,

Compute and draw the appropriate ellipse and you have the bottom portion of the side piece.

Make a pattern out of heavy paper or cardboard with the triangle and elliptical bottom and have someone hold it to the hammock side while you are in it or have someone get while you do that. See how it fits.

It might even be easier to forget the whole elliptical part and draw the bottom curved shape directly from the hammock while your assistant is in the hammock. I seriously doubt that the bottom shape will change much depending on the occupant. If I had an assistant, I would go this route.

3. I then have a piece that is sewn to the bottom portion of the above piece and fits under the hammock from hammock end to hammock end. It forms the "cup" that seals the draft stopper. This piece is very simple to make - simply lay your hammock on the floor spread out on the needed fabric with the side of the hammock aligned on the edge of the fabric. Decide on the width of the bottom "band", trace the arcs on each end down to the width of the band (allowing for hems or bias tape) and then draw the straight line from arc to arc (again allowing for hems or bias tape). That gives the band to exactly fit the underside of the side of the hammock. Sew to the end piece cut in 1 and 2 above.

The Bridge hammock is really easy to fit

Hem or add bias tape to edges, sew on tie outs and it is done.

Now for the bug netting, all you really need is steps 1. and 2. Note that if you use spreader bars on the head side and foot side of differing length as I do, then the side pieces are going to be different. I suppose you could make both to fit the head side and the foot side will just have a small amount of excess material which then means you don't have to be concerned with head and foot sides of the bug netting.

2. Originally Posted by TeeDee
You would have to try various shapes and lengths to see which you like the best. Just do some jury rigging as I did on various sizes and shapes and see which you like the best.
-------
Try and see
I just used some of the Tulle I have around to make different shapes. I guess I just saw all that extra fabric on yours toward the head end. The shape I came up with that doesn't have that bit of excess is a trapezoid with the short end toward the head. You can get walls and bring it to a triagular single point or even create a third wall toward the head and have two points and rope (like you've done).

Also, thanks for the notes on the draft stopper. Cutting up some tulle and trying different shapes, I think I can cut and elongated diamond and just cut off the very bottom most tip.

3. Originally Posted by schrochem
...
The shape I came up with that doesn't have that bit of excess is a trapezoid with the short end toward the head. You can get walls and bring it to a triagular single point or even create a third wall toward the head and have two points and rope (like you've done).
...
Scott- this would be an isoceles trapezoid, for symmetry?

this discussion comes at a mighty good time for me. I've fit bugnet to zippers to hammock body on the main long piece, will finish that tonight and then start in on the end caps.

We're going on vacation to visit family next week, and I want to be hanging in my DIY hammock in the back yard of my youth, so the push is on to make this thing bug-proof. Up where I come from mosquitos rival eclipses for darkening the sun.

Grizz

4. Originally Posted by schrochem
I just used some of the Tulle I have around to make different shapes. I guess I just saw all that extra fabric on yours toward the head end. The shape I came up with that doesn't have that bit of excess is a trapezoid with the short end toward the head. You can get walls and bring it to a triagular single point or even create a third wall toward the head and have two points and rope (like you've done).

Also, thanks for the notes on the draft stopper. Cutting up some tulle and trying different shapes, I think I can cut and elongated diamond and just cut off the very bottom most tip.
The trapezoid is a good idea. I'll shorten the length of the loft floor nearer the head side and see how that works. Changing the jury rigged shape is easy.

I still don't see the reasoning behind making a more complicated shape, i.e., the trapezoid. I just computed the weight savings of the trapezoid over a simple rectangle. If I change the rectangle to a trapezoid with the side nearer the head with a length of 21" (10" less than the foot side length) then I save 0.16 oz in weight. If I make it shorter yet to 11", then I save 0.32 oz. Shorter yet to 1", then I save 0.48 oz, but at 1" you may not (most likely not) have much in the way of "walls" to keep stuff in the loft. I'll try the trapezoid, but not really sure the tenths of an oz weight savings are really worth the more complicated shape and what you shave off the "walls". The more trapezoidal the shape, the smaller the "walls" and the more likely quilts will be overflowing and dropping out of the loft. If the reasoning behind the trapezoid is purely aesthetic, then I could see the reasoning, but otherwise see no real advantage.

Also, I'm thinking of adding a second strip of grosgrain on the underside of the loft floor half-way between the foot and head sides of the floor. I could then use the full sized loft floor when needed or fold the head side half back on top towards the foot side and just use half the loft floor when a smaller space is needed. The only cost would be a few inches of grosgrain and that wouldn't even be 0.1 oz in weight. 2 loft sizes in one.

5. Originally Posted by GrizzlyAdams
.... I've fit bugnet to zippers to hammock body on the main long piece, will finish that tonight and then start in on the end caps.

...
So you have the bug netting attached to the hammock body on the hammock ends??

No bug netting underneath - you'll be relying on clothing or blankets or .. ??

Let us know how that works.

6. Originally Posted by GrizzlyAdams
Scott- this would be an isoceles trapezoid, for symmetry?

this discussion comes at a mighty good time for me. I've fit bugnet to zippers to hammock body on the main long piece, will finish that tonight and then start in on the end caps.

We're going on vacation to visit family next week, and I want to be hanging in my DIY hammock in the back yard of my youth, so the push is on to make this thing bug-proof. Up where I come from mosquitos rival eclipses for darkening the sun.

Grizz

Yes, an isoceles trap for the gear loft.
For the end caps, I don't know what it's called but I can tell you how to get it
Like TeeDee said there is a triangle on the top portion. Using a scrap piece make a square with the sides having a length of the sides of the triangle(ie ring to ridgeline) which is probably in the area of 30".
Hang it like a diamond with the top point at the ridgeline. The top two sides will be velcroed (in my design) to bugnet going over the ridgeline.
Most likely the bottom part of the diamond won't make it to the bottom part our you bugnet, but you can measure and see how many more inches it is from the tip to the net. Mine was another 6" so the vertical diagonal is 48" long.

On another test piece ( I was just using cheap Tulle) I measured the top two sides 30" again and then found where they would meet on the opposite corner if it was a 30" square. I then took a large ruler and put it on the diagnol and moved that point out 6" from the far point (or 48" from the near one). Then I cut from the 30" mark on the upper side down (at say 100 to 120deg angle) to the new far point. Fit it once again and you should be able to sew the bottom part of the fabric to the bottom side of you net, if not make that diagonal longer....

Of course that was just the incremental way that I progressed
You could save the first step (and piece of fabric) and measure the distance from the ridgeline straight down to the bottom of you net and throw in an inch or two for hems and extra room.

Now, that should be just about as clear as mud!

7. Originally Posted by TeeDee
The trapezoid is a good idea. I'll shorten the length of the loft floor nearer the head side and see how that works. Changing the jury rigged shape is easy.

Also, I'm thinking of adding a second strip of grosgrain on the underside of the loft floor half-way between the foot and head sides of the floor. I could then use the full sized loft floor when needed or fold the head side half back on top towards the foot side and just use half the loft floor when a smaller space is needed. The only cost would be a few inches of grosgrain and that wouldn't even be 0.1 oz in weight. 2 loft sizes in one.
endless variations.....

Or you could attach string to that new piece or grosgrain and have a multi section loft
Ya know a sock drawer, bedding, pack,

Seriously, I bet if it was designed right the loft could be part of the packing system for the backpack. Stuff that isn't needed until camp like quilt, camp clothes, etc. could be packed up in there and the whole thing in a BB sack....

8. ## second skin

Originally Posted by TeeDee
So you have the bug netting attached to the hammock body on the hammock ends??

No bug netting underneath - you'll be relying on clothing or blankets or .. ??

Let us know how that works.
Yep. As does the Bear Mountain Bridge hammock, it seems, but I've got bugnet rising higher to a ridgeline that is tall enough for me to lounge in a la Lazy Boy or lounger. Or just sit up without danger of losing my ears

Outside and below I'll have the sort of adjustable second layer that Scott discovered. Could be bugnet or 1.1 oz. But _something_ to make the nasties have to work harder to get at my tender loins.

Or leave at home if not needed.

Grizz

9. Originally Posted by TeeDee
When I made the draft stopper, I just plunged ahead and used clothes pins and tucks to make the draft stoppers fit. I ended up with extra material even though the fit is pretty good.

I now know a much easier way to make the draft stopper (which I will be using on the final draft stoppers) and maybe you can extend or adapt my technique to your use:

...

Compute and draw the appropriate ellipse and you have the bottom portion of the side piece.

Make a pattern out of heavy paper or cardboard with the triangle and elliptical bottom and have someone hold it to the hammock side while you are in it or have someone get while you do that. See how it fits.
...
I remember from high school a method involving a string and nails. Since I'm going to give this ellipse thing a shot, I went a googling looking for ways to draw them and found a promising string free method.

Grizz

10. teedee... i was pretty amazed to read your post (# 77) on this thread after you in particular used so much time & space trying to spin your lawyer sounding thread, defending tom h, or attacking those that were speaking out against how far he was attempting to use his patents to keep others from using ridge lines & such.
here's your post...

"You enter/exit over the cat cut "ends"

Okay - I am deliberately calling the cat cut portions the "ends" of the hammock. A regular hammock is supported on the "ends" of the hammock.

That defines the "end" of a hammock, the portion where it is supported.

This hammock is also supported on the "ends" of the hammock. The big difference is that the "ends" of a regular hammock are oriented such that they are pointed at the two supporting trees.

This hammock is rotated 90 deg so that the "sides" of the hammock are pointed towards the supporting trees and the "ends" of the hammock are oriented such that they are on a line perpendicular to the tree centerline.

Also, in a regular hammock the length of the hammock from "end" to "end" is longer than the width of the hammock, i.e., the dimension perpendicular to the "end" to "end" centerline.

For this hammock, the length of the hammock from "end" to "end" is shorter than the width, i.e., the dimension perpendicular to the "end" to "end" centerline.

I am doing this very deliberately.

I have not read TH's patent on the structural ridge line (nor am I an attorney patent attorney or otherwise), but from the little bit of information I have been able to glean from those that have read his patent, I understand that he describes his "ridge line" as setting the sag from "end" to "end" of the hammock. TH in his reply to the "patent" thread on the forums, describes his ridge line as setting the "sag" of the hammock and the commonly accepted usage of sag is from "end" to "end". I think if you read his web site, that is the interpretation that TH uses.

Well for this hammock: the spreader bars set the sag, NOT the ridge line. Also, there are 2 spreader bars which set the sag semi-independently on each "end" of the hammock.

The ridge line for this hammock sets the flatness of the hammock. It sets the bow of the hammock from "side" to "side" NOT from "end" to "end".

Now if I am correct in this interpretation, then TH's patent would not cover the ridge line as I have incorporated it in this hammock and, from the picture of the JRB hammock, it would not cover their ridge line either.

As I understand patents, the writer has to be excruciatingly specific as to what is being patented. As such the terms used to describe the patent have to be those in common usage or well defined in the patent. So if TH describes the ridge line as being from "end to end", then the patent does not cover a "side to side" ridge line. I may be entirely wrong in this, but I can only try.

If am right and the courts would happen to agree, then anybody is free to make and sell hammocks of this design incorporating a ridge line that sets the "flatness" of the hammock and not violate TH's patent which covers a ridge line which sets the sag. That solves the problem that people have with TH's patent. At least for this type of hammock. This type of hammock has been in the public domain too long for anybody to obtain a valid patent on it.

As I tried to point out on the other thread, cussing out TH for protecting his intellectual property and patents is not the best course of action. It is a losing action. The best course is to do what TH did, innovate a different/better system.

Now, having written that, please just understand why I am using the terminology I am using and do NOT start discussing the validity or invalidity of TH's patent - that discussion has run it's course. Let it die."

if that's not the biggest bunch of hog wash, i don't know what is.
the point i was making about tom hennesy's business practices were plain & simple, & they still are.

i despise the ways of those that learn & practice the ways of a spin doctor.

a lot of people make a big deal about having the right to free speech, well guess what, if i want to say how i feel about tom hennessy's ways, i'll do so.
and if you or any body else don't like it, that's really just tough.
i'll try to be nice about things as long as people will alow me, but at some point when certain people keep wanting to express their anger by attacking me w/ hogwash, you better believe i'm going to lay the facts out so you can understand them.
and i'm not talking in tricky little circles.
as for the jacks & their patent pending on the bear bridge hammock, i really don't know just how to answer that question. as far as i can tell they aren't trying to take any bread off any one else's table. no one was selling that hammock.
if you want to hash that out w/ them, then be my guest, but if you still want to
1) bring up my speaking out against tom & defend his patent,
2) then turn around & call the sides of your hammock the ends & vice versa in order to get around tom's ridge line patent,
3)then turn around again & begin to throw off on the jack's patent on the bear bridge hammock, then you can expexct that i'll be calling you on that one bud. ...tim

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