OK, It's JRB Bridge time!

Printable View

11-23-2007, 12:40
BillyBob58

OK, It's JRB Bridge time!

Well, guess what the mail man brought this AM? A shiny new JRB Bridge Hammock! I am down with a bad cold and it's cold and windy out, but I'm dieing to set it up! I may have to suck it up and layer up, hang the hammock and put my pad in. ( No UQ available! :mad: ) My wife just left to go shopping after having a fit about me getting another hammock! I don't know what her problem is! :confused: But I think I will go up into the attick(sp?), drag down the Christmas tree and decorations which she wants to start on today, and then see about playing with my early package from Santa. :D
11-23-2007, 12:45
headchange4u

How's it feel to be the first? That's awesome. Congrats.
11-23-2007, 12:51
BillyBob58

Thanks! It feel's great, I just hope my illness doesn't delay my testing, in which case I won't be the first in that way. First thing, it weighs a tad more than specified, at least including the stuff sack which contains everything-hammock, net and spreader bars: about 35 oz on my low tech kitchen scales.
11-23-2007, 16:16
angrysparrow

I got mine in the mail today, also. It looks to be a very well made piece of kit.

Sadly, I won't get a chance to test it until at least Monday, though.
11-23-2007, 17:53
BillyBob58

Any suggestions?

Well, sick or not, I got it up. I have great news and bad news. Flat as a board,great comfort in all ways but one. SHOULDER SQUEEZE! Not a lot, but enough that I am afraid it will distract from the overall great comfort.

So with this hammock, should I hang it a little looser, as with my Speer, to get rid of this problem? Or is there nothing that can be done with this type of hammock? I am a big guy, but not THAT big. I'm a fraction under 6'1", 205lbs. I am 45" around the chest and 49" around my shoulders. Is this too big for this hammock?

The posts I am hanging from may be part of the problem, causing some extra sag ( good or bad with this hammock?) once I get in. Before I get in, the outer rings are 9'3" apart. I will try to get them a little closer to the recommended 9'6" ( less sag if I do that, right?) Or I may be doing something wrong with the spreader bars. I followed the directions as best I could.

PS I just put my 25" wide thermarest camprest in the bottom. That helped a lot, but not completely. And of course, it's a pad. Ideas? I also got closer to the 9'6" spread reccomended.
I must be doing something wrong. It is rated for 6'3" 250 lbs. Surely this hammock should be big enough for me? I could just e-mail the jacks, but I figure they will see this, plus there are experienced Bridge hammockers here.

Any ideas?
11-23-2007, 18:28
GrizzlyAdams

Quote:

Originally Posted by BillyBob58

Well, sick or not, I got it up. I have great news and bad news. Flat as a board,great comfort in all ways but one. SHOULDER SQUEEZE! Not a lot, but enough that I am afraid it will distract from the overall great comfort.

So with this hammock, should I hang it a little looser, as with my Speer, to get rid of this problem? Or is there nothing that can be done with this type of hammock? I am a big guy, but not THAT big. I'm a fraction under 6'1", 205lbs. I am 45" around the chest and 49" around my shoulders. Is this too big for this hammock?

The posts I am hanging from may be part of the problem, causing some extra sag ( good or bad with this hammock?) once I get in. Before I get in, the outer rings are 9'3" apart. I will try to get them a little closer to the recommended 9'6" ( less sag if I do that, right?) Or I may be doing something wrong with the spreader bars. I followed the directions as best I could.

PS I just put my 25" wide thermarest camprest in the bottom. That helped a lot, but not completely. And of course, it's a pad. Ideas? I must be doing something wrong. It is rated for 6'3" 250 lbs. Surely this hammock should be big enough for me? I could just e-mail the jacks, but I figure they will see this, plus there are experienced Bridge hammockers here.

Any ideas?

The squeeze you get in a bridge hammock depends on the width of your shoulders, the spreader bar length, the width of the fabric between the spreader bar endpoints, and the horizontal distance of your shoulders from the spreader bar. Of these, for the BMBH I know only that the spreader bar is 30".

I have no shoulder squeeze in my DIY bridge with a 36" spreader separation, a fabric width of 51" under that spreader, and my shoulders 18" away from the spreader bar. So shoulder squeeze is not endemic to the bridge design.

TeeDee, Scott, WalkingBear, and I have all built ours with spreader widths in the 34-40" range, and have tended to start with the full 60" width of a roll of fabric. Maybe the other bridge engineers will weigh in with their experiences. The 51" I have under the spreader bar is due to the bar being recessed along the suspension curve, at a point where the fabric was cut narrower because of the curve.

Sag does not affect shoulder squeeze.

Should not be a problem either for side-sleepers.

Finally, laying in the bridge hammock is definitely a different sensation. Could be that "squeeze" is more a matter of "sensitivity to the hammock walls swooping up past your ears, touching your shoulders along the way." In short, with time perhaps you will not notice this.

Then again, maybe BMBH truly squeezes your shoulders. Good for the Jacks to have this data.

Anybody ever mention that it isn't that hard to make your own bridge hammock? How's your sewing skills? Shoot, I learned to sew making my first one. ;) (and that one has long since been retired....)

Grizz
11-23-2007, 18:53
BillyBob58

My sewing skills do not yet exist. And I do have this one now, so I would prefer to get it working right. That seems to be a pretty good difference in spreader bar width between yours and JRB. It may be a sensitivity issue, and they mention something about the netting being a little to long until some hammock stretch occurs. Maybe some stretch will make a dif. Does yours touch your shoulders at all. Of course side sleeping solves the problem, and that is wonderfully easy to do, for the first time.

I think I will go ahead and contact the Jacks.
Bill
11-23-2007, 19:50
GrizzlyAdams

Quote:

Originally Posted by BillyBob58

...
Does yours touch your shoulders at all.
Bill

no, by my deliberate design (on the 4th version!) I was getting a little squeeze on earlier versions where the spreader bar was 34", and out in front of the hammock by a couple of inches.

Grizz
11-23-2007, 20:01
BillyBob58

Quote:

Originally Posted by GrizzlyAdams

no, by my deliberate design (on the 4th version!) I was getting a little squeeze on earlier versions where the spreader bar was 34", and out in front of the hammock by a couple of inches.

Grizz

Thanks. I have e-mailed the Jacks. I'll let you know what they say. But I'm beginning to suspect a 30" spreader, or whatever, will just not be quite wide enough for me. Though I hope not, cause that would be a real bummer. Because otherwise, that baby is comfortable, including as a chair/lounger.
Bill
11-23-2007, 20:13
schrochem

I would say that 30" at the head end (at the tips, not like Grizz') is a bit narrow. However, this is only if you are on your back or fully on your stomach. Besides my other bars, I typically put the 42" 1X2 on the head end. However, I am a side/stomach sleeper, so all this really isn't an issue for me. Actually, thanks for the reminder. I think I'll chug along with my 36" tent poles....
Actually, I have a lot of updating to do to get my bridge where I want it. Grizz has come up with some swell ideas. I just need to do them. Another hobby kinda dethroned the bridge mods.
11-23-2007, 20:24
Mule

Quote:

Originally Posted by GrizzlyAdams

no, by my deliberate design (on the 4th version!) I was getting a little squeeze on earlier versions where the spreader bar was 34", and out in front of the hammock by a couple of inches.

Grizz

GRIZ, I JUST PRINTED OUT YOUR INSTRUCTIONS FOR THE BH AND WILL BE PRESENTING YOU WITH A 'B FLAT' MODEL SOON. STEVE
11-23-2007, 20:31
GrizzlyAdams

Quote:

Originally Posted by BillyBob58

Thanks. I have e-mailed the Jacks. I'll let you know what they say. But I'm beginning to suspect a 30" spreader, or whatever, will just not be quite wide enough for me. Though I hope not, cause that would be a real bummer. Because otherwise, that baby is comfortable, including as a chair/lounger.
Bill

I wager that with some mods (that would blow the warranty naturally) you could get the hammock to have a wider spread.

The painful part would be to cut the end caps down the center, hem the cut edges, and once you've settled on the spread you want, sew in a piece that fills in the wedge in the middle of the endcap caused by spreading the ends farther apart. Then you'd need to find a replacement for the spreader bars, but hiking poles can be used for that, Scott found some tent poles that work. Finally you'd want to replace the suspension from the rings out, because with a wider spreader base you want longer suspension sides. As long as you're at it, put in a structural ridgeline.

You've lost a bugnet that fits, the design of that is simple and could be replicated to fit the new shape.

or you could just get used to the squeeze....

Grizz
11-23-2007, 20:37
GrizzlyAdams

Quote:

Originally Posted by skskinner

GRIZ, I JUST PRINTED OUT YOUR INSTRUCTIONS FOR THE BH AND WILL BE PRESENTING YOU WITH A 'B FLAT' MODEL SOON. STEVE

Mule- one thing the instructions don't discuss is the later development of moving the head spreader bar back. From a spreading point of view this is the same as making the hammock starting with a narrower piece of fabric, e.g. 54" rather than 60". I.e. you can get the benefits of that spread without fussing with a recessed spreader bar, by starting out with a somewhat narrower piece of fabric. Either by recessing the spreader bar or narrowing the fabric, this is a mod worth doing.

Looking forward to the B flat (which I think was HC4U's joke at RRG, actually).

Grizz
11-23-2007, 20:42
Mule

Quote:

Originally Posted by GrizzlyAdams

Mule- one thing the instructions don't discuss is the later development of moving the head spreader bar back. From a spreading point of view this is the same as making the hammock starting with a narrower piece of fabric, e.g. 54" rather than 60". I.e. you can get the benefits of that spread without fussing with a recessed spreader bar, by starting out with a somewhat narrower piece of fabric. Either by recessing the spreader bar or narrowing the fabric, this is a mod worth doing.

Looking forward to the B flat (which I think was HC4U's joke at RRG, actually).

Grizz

Griz, At this time the concept of starting with a narrower piece of fabric or 'resessing' the spreader bar is not clicking with me. Maybe after I study the plans it will make sense. Thank pal, Mule
11-23-2007, 21:08
GrizzlyAdams

1 Attachment(s)

Quote:

Originally Posted by skskinner

Griz, At this time the concept of starting with a narrower piece of fabric or 'resessing' the spreader bar is not clicking with me. Maybe after I study the plans it will make sense. Thank pal, Mule

have a stroll through my photo gallery and you'll see that in the later pictures the spreader bar at the head is not at the end of the hammock---it is about 1 foot back. At the head end there are 2 sets of rings : the furthest pair out have the suspension lines tied to them, the recessed ones have the hiking pole passing through them.

That the fabric is narrower under the spreader bar than at the head is one of geometry. The original piece of fabric was cut before I decided to move the spreader bar back. So it was cut like the directions would have you do it, a suspension curve from end to end. After the cut, the width of the fabric between suspension lines at the point where the spreader bar ends up is narrower. See attachement. What I'm saying is that if you cut the fabric narrower to begin with (the light blue in the picture) and put the spreader bars at the head and foot as before, you'd get the benefits of the recessed spreader bar, at least with respect to the lay of the hammock and spread.

Grizz
11-23-2007, 21:11
schrochem

Hey Grizz, i thought the main reason you did the recessed pole was to reduce the compression forces on your hiking poles. Are you saying there is another reason I somehow overlooked....
11-23-2007, 21:21
GrizzlyAdams

Quote:

Originally Posted by schrochem

Hey Grizz, i thought the main reason you did the recessed pole was to reduce the compression forces on your hiking poles. Are you saying there is another reason I somehow overlooked....

still true. with a 36" suspension base I'm getting the same spread with less compression than I would get if the pole were at the head of the hammock, at (I dunno, maybe) 40", and a correspondingly greater compression.

You can get that spread without recessing the pole by starting out with narrower fabric. I realize of course AFTER I build the thing!

Grizz
11-23-2007, 21:58
Mule

I 'think' I get it.

By your pictures 'on your back' it appears that you then had the spreader NOT recessed. In the picture 'on your side' you show it recessed. If I am getting you correctly, lower compression was only one of two reasons for recessing the spreader back toward you from the actual end. The other reason would be to maximize the spread where it counts, ie., closer to your shoulders, which effectively gives you less shoulder squeeze without needing more fabric width. Now, you not only have the parabolic curve looking from the side, you also have one looking down. The curve looking down starts at the recessed spreader in both pictures, but is made to start wider at the position of your shoulders in the recessed version.
I know this is going to sound confusing but I think you have already figured this out. Here goes:
My thinking is that to leave the parabolic curve longer and use longer spreaders to get the same shoulder squeeze relief at the point of your shoulders would be more effective in providing space in the hammock while occupied, and the compression could be easily adjusted to the same force by lengthening the triangle from the spreader to the tree. Using a 36 inch spreader, subtraction of the angle from 60 degrees included to say, 50 degrees included would lengthen the triangle by 7.4 inches. See difference using c / tan C, (or side opp / Sin of C.)
I used 50 degrees included angle because using a set of scales, pulling a 60 degree included angle one inch took the same force as pulling a 50 degree angle one inch, 24 ounces both cases. Only the length of the side adjacent changed.
Conclusion, Since my crude force data using a scale in ounces shows the same force virtually from the spreader to the tree, the force on the spreader, or the side opposite should be equal too using a 38.6 inch triangle instead of a 31.2 side adjacent like i 'think' you are using. Ha, this is fun!
Steve (Mule)
11-23-2007, 22:38
BillyBob58

I laid out for an hour or so, at 36*. With my Thermarest Camprest in the pad pocket. With the pad in and a pillow under my head, the problem is not as noticeable. It really is more of an "elbow" problem than it is a "shoulder" problem, and it is really easily overcome by having my hands resting over my chest/stomach rather than by my side. As in this picture from JRB website. http://216.83.168.206/index_files/BM...r%20Pocket.jpg Though I wonder if that will lead to some cold spots at the elbows. I was extremely warm and very comfortable, even though I was on a pad. Then sometimes my elbows are actually out a bit over the hammock edge. Of course, none of this was a problem if I turned to my side a little or completely. Which was very easy to do. This hammock makes staying on the pad a non-issue.

But I'm starting to get the feeling this hammock design is not quite wide enough for folks who are broad shouldered or other than pretty slender, even if they are well below the upper weight limitations.
11-23-2007, 22:42
Mule

Quote:

Originally Posted by BillyBob58

I laid out for an hour or so, at 36*. With my Thermarest Camprest in the pad pocket. With the pad in and a pillow under my head, the problem is not as noticeable. It really is more of an "elbow" problem than it is a "shoulder" problem, and it is really easily overcome by having my hands resting over my chest/stomach rather than by my side. Though I wonder if that will lead to some cold spots. I was extremely warm and very comfortable, even though I was on a pad. Then sometimes my elbows are actually out a bit over the hammock edge. Of course, none of this was a problem if I turned to my side a little or completely. Which was very easy to do. This hammock makes staying on the pad a non-issue.

But I'm starting to get the feeling this hammock design is not quite wide enough for folks who are broad shouldered or other than pretty slender.

BillyBob, with a simple addition of a triangle of fabric in the head end cap of the hammock, you could possible insert a six inch longer spreader bar. Just a thought. Mule
11-23-2007, 23:26
schrochem

I'll reiterate that the strength of a bridge style hammock is for side, side/stomach, or stomach sleepers. You can minimize that shoulder squeeze but it's gonna take certain characteristics (that grizz pointed out). 'Elbow' issue is a good one to point out and is also something to watch out for on your side. There is the undermost arm that, at first, seems to not find a comfy spot.
11-23-2007, 23:36
GrizzlyAdams

Greek alphabet soup

Quote:

Originally Posted by skskinner

... I know this is going to sound confusing but I think you have already figured this out. Here goes:
My thinking is that to leave the parabolic curve longer and use longer spreaders to get the same shoulder squeeze relief at the point of your shoulders would be more effective in providing space in the hammock while occupied,

true, but the way I lay the change in space is above my head, and serves mostly as a place I can store things (like an extra quilt). The difference in space isn't so large, and since I'm not personnally up there I don't notice the difference.

Quote:

and the compression could be easily adjusted to the same force by lengthening the triangle from the spreader to the tree.

you got it. Until recently my suspension had the apex of the triangle way up at the tree, minimizing compression. I came to see that I really wanted a ridgeline to make set up among different sites easy, which required me to settle in on a length for the suspension sides.

Quote:

...
Ha, this is fun!
Steve (Mule)

Watch out folks, someone else has discovered the joys of using trig to compute compression forces. Greek symbol potporri here we come again! :)

Grizz
11-23-2007, 23:46
GrizzlyAdams

Quote:

Originally Posted by BillyBob58

I laid out for an hour or so, at 36*. With my Thermarest Camprest in the pad pocket. With the pad in and a pillow under my head, the problem is not as noticeable. It really is more of an "elbow" problem than it is a "shoulder" problem, and it is really easily overcome by having my hands resting over my chest/stomach rather than by my side. As in this picture from JRB website. http://216.83.168.206/index_files/BM...r%20Pocket.jpg Though I wonder if that will lead to some cold spots at the elbows. I was extremely warm and very comfortable, even though I was on a pad. Then sometimes my elbows are actually out a bit over the hammock edge. Of course, none of this was a problem if I turned to my side a little or completely. Which was very easy to do. This hammock makes staying on the pad a non-issue.

But I'm starting to get the feeling this hammock design is not quite wide enough for folks who are broad shouldered or other than pretty slender, even if they are well below the upper weight limitations.

sounds like things are coming around for you, which is best. To get more spread you need wider bars, and this turns out to have ramifications...basically you need a wider tarp and a longer suspension; the shortest distance between a pair of trees you can hang from increases. My guess is that JRB worked through the tradeoffs, and settled on a design that perturbed the rest of the system the least. Which is likely a good call on their part from a business point of view.

Grizz
11-23-2007, 23:58
Cannibal

Quote:

Originally Posted by GrizzlyAdams

Watch out folks, someone else has discovered the joys of using trig to compute compression forces. Greek symbol potporri here we come again! :)

Grizz

Nooooooooooooooooooooooooooooo!

Actually got to try one of these bridge things today, thank you schrochem. I think I kind of like it. Might just have to make one over the next couple of weeks. Now that I've seen and touched it I realize that it can be copied without a sliderule. :D
11-24-2007, 00:19
FanaticFringer

Didn't you mean "Geek" symbol potporri here we come again! :p :D :eek:
11-24-2007, 00:30
FanaticFringer

Will report on my Bridge tomorrow. Cant wait.
11-24-2007, 00:56
Mule

A little off the subject, but, does anyone know why the ENOs have those heavy i inch webbing on the bottom of their stuffsacks on both the hammock and the bug net. Is there any reason why I shouldn't cut them off?
11-24-2007, 01:18
GrizzlyAdams

Quote:

Originally Posted by FanaticFringer

Didn't you mean "Geek" symbol potporri here we come again! :p :D :eek:

I suppose I did. Just as Best Buy has its Geek Squad, so does HF. Looks like Mule wants to join up!

Grizz (they call me the Geek...)
11-24-2007, 01:58
Cannibal

Quote:

Originally Posted by skskinner

A little off the subject, but, does anyone know why the ENOs have those heavy i inch webbing on the bottom of their stuffsacks on both the hammock and the bug net. Is there any reason why I shouldn't cut them off?

They are just there for compression, I believe. Absolutely no reason you couldn't chop em.
11-24-2007, 01:59
Mule

Quote:

Originally Posted by Cannibal

They are just there for compression, I believe. Absolutely no reason you couldn't chop em.

thanks Cannibal. Mule
11-24-2007, 10:21
greggg3

I cut that straps off my ENO double, like about 15 minutes after I received them. I couldn't see that they were anything but excess weight. (I like my stuff to be sorta squishy for packing (like the McCat stuff sack), as opposed to minized volume but drum tight and hard as a rock).
11-24-2007, 10:28
Mule

Quote:

Originally Posted by greggg3

I cut that straps off my ENO double, like about 15 minutes after I received them. I couldn't see that they were anything but excess weight. (I like my stuff to be sorta squishy for packing (like the McCat stuff sack), as opposed to minized volume but drum tight and hard as a rock).

Me too, Mule