Discuss - Guide to Making a Bridge Hammock

**Gumbi** · 08-13-2008, 12:48

Awesome set of instructions! Great work!

**GrizzlyAdams** · 08-24-2008, 19:11

Hi Bear Rider, I missed this post; I was busy using my hammock when you made it, and then I didn't review everything that happened that week. I just wandered back now to make a post about an update to the instructions, and saw it.

Originally Posted by Bear Rider

First, I saw where you fold the body material along the long axis for cutting so that both sides are identical. Since the curve is symmetrical, couldn't you make one more fold on the short axis so that all curves are symmetrical and identical? This would also shorten the length of the cut that you have to make by half.

Sure, I've done that. Might even have done it on this cutting, not sure. If not, it's because my roller cutter needed a new blade. It does not take long for a new blade to dull enough so that one pass over fabic still leaves some threads uncut. Also, as RamblinRev points out above, there is a certain risk involved in getting the four layers lined up just so. But sure, using pins and clips and a new blade, folding into quarters works just fine.

Second, on the mosquito netting, has anyone given a thought to constructing the net in the form of a "mini bridge" suspended above the hammock? If you made the length and width of the top panel smaller than the hammock body, and made the sides long enough to hang down alongside the hammock body, it might be possible to simply drape the netting over the hammock in the manner that traditional mosquito netting is draped over beds, without worrying about fasteners.

I've thought about netting that just drapes, no fasteners. This works fine on gathered end hammocks because the widest part to cover is in the middle, so the draped netting gets pushed out the furthest there and than settles in naturally along the sides creating a "seal" almost. Not so with the bridge. The widest points are the spreader bars, and the hammock body curves in at the middle. So if you drapped a net you'd get an air gap between the hammock side and the drapped net, at the middle. Now TeeDee has a solution I think that drapes a bugnet and uses belly bands or some other kind of device to pull the netting in...you'll have to look that up in his guide. I like a zipper and sewn in netting. Personal preference. With the DWB I've especially appreciated being able to have the netting over me or not. Will be a standard feature for any of my future hammocks that have netting.

Thanks for the interest. Looking forward to a report on your hammock!

Grizz

**Ramblinrev** · 08-25-2008, 18:47

My wife looked at me with that aghast look on her face and said "WHAT are you making now....?" I almost didn't have the heart to tell her. But I figured I'd better. Using this guide as a template I am constructing a dual layer bridge with the self-attached end caps from Turkeyboy's setup. I am seriously interested in having a bridge of my own, rather than just the one for flamingo and the DMB BEEP is a nice novelty which I hope to use at some point. But I really like the way the bridge lies and I can get out of it w/o the BEEP. So... I have the body more or less constructed... I need to finish the endcap folding and sewing and then begin to work on the top side.

I am hoping this will be a cold weather hammock when I finally get done with the wind shielding and the pad pocket. The solid end caps will cut down on the breeze that's for sure.

Anyway.. she's on to me now. I can't hide in my room and be ignored any more.

**Schneiderlein** · 12-08-2008, 11:45

Great directions, Grizz. I was watching your history lesson video, and it has inspired me to make a bridge hammock. The one in the video looks quite different from the one described here. I tried to look through the bridge hammock thread to see if there is more information, but gave up after about 20 pages.

There are a few things I'm unclear about:

1. How long does the fabric for the head end cap extend, and is it cut at an angle where the suspension cord is threaded through the channel?
2. How big is the cut-out for the head-end spreader bar? Is it just a semi-circular cut-out that you hemmed?
3. I assume the main body is a trapezoid. For the parabolic cut, do you simply rotate the parabola, i.e., make the long edge of the trapezoid the x-axis? Or do you compute the parabola differently?
4. I am not sure if I want to go with the really narrow foot end on the first one. What would be appropriate dimensions for the trapezoid and parabola depth for a head-end spreader of 36" and a foot-end spreader of 24"?
5. I'd like to use rope instead of webbing for the suspension arc (simply because I have plenty of it). Any hints on how to best do this?

Thank you again for the great directions and the great video. After looking at it for a bit, it seems like bridges are easier to make than I thought.

**GrizzlyAdams** · 12-08-2008, 13:18

Originally Posted by Schneiderlein

Great directions, Grizz. I was watching your history lesson video, and it has inspired me to make a bridge hammock. The one in the video looks quite different from the one described here. I tried to look through the bridge hammock thread to see if there is more information, but gave up after about 20 pages.

Ah ha! The propaganda campaign is working!

There are a few things I'm unclear about:

1. How long does the fabric for the head end cap extend, and is it cut at an angle where the suspension cord is threaded through the channel?

Am away from home and hammock for a bit this week...but an estimate is 18". It is cut at an angle. Takes the unfinished fabric from being about 51" wide to being about 37" wide, in that 18".

2. How big is the cut-out for the head-end spreader bar? Is it just a semi-circular cut-out that you hemmed?

Isn't actually cut. The edges of the head cap are hemmed, and a few inches past the spreader bar are folded over to make the channel.

3. I assume the main body is a trapezoid. For the parabolic cut, do you simply rotate the parabola, i.e., make the long edge of the trapezoid the x-axis?

Exactly.

4. I am not sure if I want to go with the really narrow foot end on the first one. What would be appropriate dimensions for the trapezoid and parabola depth for a head-end spreader of 36" and a foot-end spreader of 24"?

Here's my logic on that...I imagine having a parabola at the head and at the foot, with the center of the speader bar being x=0, and the extreme point being at x=0 as well. Imagine the spreader bar as a constant line, y=h, so that the minimum distance from y=h to the low point of the parabola is the height, h.

Given spreader bars SH long at the head, and SF long at the foot, I want to find out the arc length of the parabola at the head, and the arc length at the foot, such that in both parabolas the height is h. These arc lengths give me the base lengths of the trapezoid.

I do this numerically, looking for that h which, when SH=36" gives me an arc length of 48". Given that h, I compute the arc length of the foot end parabola with SF=24". That gives me an arc length down there of 39". You can make the trapezoid whatever length you like. What these figures omit is the extra margins for rolling webbing in or creating a channel. What they include is the height of the cut of the suspension parabola. When I made mine I first computed the dimensions as above, added the allowance for rolling the webbing, marked the trapezoid on the fabric, computed the suspension curve (cut out of the still-virtual trapezoid), and then cut.

5. I'd like to use rope instead of webbing for the suspension arc (simply because I have plenty of it). Any hints on how to best do this?

I've done this a couple of times. For the channel I allowed for a double layer of fabric, and a hem seam wide enough to take two lines of stitching to hold it.

The body will slide to the middle under weight unless you do something about that. I have both times sewed tabs of webbing (pictures in my gallery) at the ends of the channel, and essentially tied the suspension cord off at the tabs. This has worked fine.

Thank you again for the great directions and the great video. After looking at it for a bit, it seems like bridges are easier to make than I thought.

Thanks, glad you like the video.

I think the analysis we did in the early days scared people off. Once you have the measurements you want worked out, the cutting and sewing isn't bad. If you have some other questions along the way, feel free to ask.

Grizz

**Ramblinrev** · 12-08-2008, 13:24

I find rope in the suspension sides of a bridge to be very problematic. The thin cross section cuts into my legs very painfully. Not to say you shoudln't use what you got. But that is something to think about. If you plan on sitting over the side as a chair you might want to plan some kind of padding to carry with you. My strong preference is webbing.

**TiredFeet** · 12-08-2008, 13:50

Originally Posted by Schneiderlein

............
4. I am not sure if I want to go with the really narrow foot end on the first one. What would be appropriate dimensions for the trapezoid and parabola depth for a head-end spreader of 36" and a foot-end spreader of 24"?...........

Schneiderlein - TeeDee has the equations and an Awk program for computing the needed parabola for the end caps. Inputs needed are the fabric width which is the length of the parabola arc and the spreader bar width.

All of it is at the end of Section 7 of his article on building a Bridge.

**Schneiderlein** · 12-08-2008, 14:04

Thanks, Grizz. I think I got the bit about computing the fabric width at the foot end using the parabola and the constant height. What I do not know is what depth the parabola for the suspension arc should be. I also could not follow what you meant by

Originally Posted by GrizzlyAdams

[...]What they include is the height of the cut of the suspension parabola.

I'm not sure how the fabric width at the ends is influenced by the suspension parabola.

I saw the pictures with the webbing at the end of the channels to keep it from bunching. I'll give this a try.

When you finish the rope channel, do you go back and try to sew as close to the rope as you can, e.g., using a zipper foot? Would this help to reduce bunching?

**Schneiderlein** · 12-08-2008, 14:12

Originally Posted by Ramblinrev

I find rope in the suspension sides of a bridge to be very problematic. The thin cross section cuts into my legs very painfully. Not to say you shoudln't use what you got. But that is something to think about. If you plan on sitting over the side as a chair you might want to plan some kind of padding to carry with you. My strong preference is webbing.

I want to do the first one on the cheap. All I have is rope and 1" poly webbing. I was thinking about using the 1" webbing and sewing it to the raw edge of the suspension arc at 1/8". Then, I would sew along the other side of the webbing at 1/8" also. To finish, I would fold the webbing in half and put down two lines of stitching. This would encase the raw edge and give me two layers of fabric between the webbing. I think it would probably hold. Has anybody tried this?

Between rope and folded over 1" webbing, what would you recommend I try?

**Schneiderlein** · 12-08-2008, 14:15

Originally Posted by TiredFeet

Schneiderlein - TeeDee has the equations and an Awk program for computing the needed parabola for the end caps. Inputs needed are the fabric width which is the length of the parabola arc and the spreader bar width.

All of it is at the end of Section 7 of his article on building a Bridge.

Thanks, TiredFeet. I see now that my question was not really clear. Computing the end panel shape is not the problem. I was wondering how to come up with the suspension depth.