Any new bridge hammock designs?

[cmoulder]

But there is a reason I gave up on end bar models years ago so I don't want to get too far ahead of myself here either as this wouldn't be the first time I've watched a promising bridge go poof after 60-90 days.

JB, what are the failure points in your experience?

[Just Bill]

JB, what are the failure points in your experience?

Asses and elbows....

Asses- When you sit in a bridge you are concentrating your full weight at the lowest and narrowest portion of the bridge. This can be as a little as 18" x 18" of fabric...2.25sf (or less). 200lbs/2.25= 88.9 lbs per sqft for an average bridge. An 11' GE you're on say 2'x11' of fabric or 22sf. 200/22= 9lbs per sf for an average GE.

The other way to consider it as you sit in on one edge... that edge (5' or so in a recessed bar vs 7' or so in an end bar) is taking your full load.
A narrow gathered end has 5' of channel on each side or 10' total. 200lbs/10= 20PSF. 200lbs/5= 40PSF.

So when I say bridge put much more stress on fabric those are some very rough numbers that quantify it. (I'm still just a carpenter, so you engineers will have to deal with my back of napkin structural analysis).
As a simpler rule of thumb- I say figure 2/3rds. So a 300lb rated fabric in a GE can support 200lbs in a basic bridge. As you push the geometry and/or minimize the suspension components... you further stress things and may see stress failures as low as 50% of the rating.

Elbows- end bar or recessed bar ...wherever the poles attach is the second highest stress point. I say elbows because when you lay there with your arms folded under your head it tends to be the head side near your elbows that wears out. Generally torso's are heavier than legs so that end gets loaded more. In equal bar designs it's not quite as bad but in unequal bar designs where the head end is wider than the foot then it's almost always the 'elbow' side of the bridge that begins to wear.

After that it's simple load cycling and use. Fabric, stitches, suspension (webbing or chord/channel design).

As mentioned before... play it 'safe' and use heavier components and things get easier or even unnoticeable over time unless you really do a sloppy job on your stitching.

Push it to the limits and the weak points are much more apparent.

Build HyperD 1.0 with 1/2" grossgrain suspension for 200lbs and you'll see it easily enough, lol.

[cmoulder]

Thanks for the great rundown and the rationale for each. The stress points seem pretty obvious but I had not considered that sitting sideways puts more stress on it compared to a GE.

[Intimidator]

Asses and elbows....
.

New book?

[Just Bill]

New book?

Don't think I'll ever do a carpentry book... but it would be a fine title.
Caint quite say where it come from original like... but when I was doing production framing it's something many a foreman would yell when folks were stick framing houses.
If your crew was moving asses and elbows is all you could see.

Course seems I'm the *** as my back is now as crooked as me elbow... but it does force you to get creative with yer bridges.

Speaking of new publications though- should have your copy of my latest back intervention device 'Just a Bigger Bridge' headed your way this week.
Figured I'd take mine out to the group hang this past weekend just to be sure afore I sent yours. Feedback was good even for a few folks bigger than you.

[Intimidator]

Don't think I'll ever do a carpentry book... but it would be a fine title.
Caint quite say where it come from original like... but when I was doing production framing it's something many a foreman would yell when folks were stick framing houses.
If your crew was moving asses and elbows is all you could see.

Course seems I'm the *** as my back is now as crooked as me elbow... but it does force you to get creative with yer bridges.

Speaking of new publications though- should have your copy of my latest back intervention device 'Just a Bigger Bridge' headed your way this week.
Figured I'd take mine out to the group hang this past weekend just to be sure afore I sent yours. Feedback was good even for a few folks bigger than you.

Look forward to giving you my feedback. Maybe we can hop on a phone call sometime soon. I always enjoy chatting with you.

[Just Bill]

Look forward to giving you my feedback. Maybe we can hop on a phone call sometime soon. I always enjoy chatting with you.

I'll see what I can do... maybe we can catch up once it gets there on the evening or weekend.
Mums the word as I know you understand... but this is a new way to build a bridge so I'm excited to see how it holds up.

I do like that UHMWPE pack webbing as well... but may be leaning towards the 2.2 stuff overall for these. The pack webbing was by far my favorite to work with but the 2.2 better matches the project thus far.
The Kevlar will be a bust long term I think...just the wrong weave for this application. So the UHMWPE stuff is leading the race thus far. On the screaming light models the 1" mil-spec grosgrain did suprisingly well. Even made a Hybrid 1.2 model with that that holds me and a HyperD 1.0 that came in at 10.75 ounces I was able to get in without any explosions...might find a 150lb person to try that out just for fun.

Peppy has one of the more promising UL models at barely under 12 ounces... but I also just finished a hybrid version of the Luxury that came in at 17.25 ounces including the spreader bars.
So hopefully overall this leads to some interesting new possibilities if it holds up.