Calling all Bridge Masters, looking for input

[BER]

I am in the planning stages for DIY bridge #2, awaiting supplies, and decided to plan my measurements today. I hung my DIY bridge #1, my modified Eureka Chrysalis (2010 version), layed around a bit, took measurements and compared them to the measurements I gleaned from Grizz's recent 3 part video series on the Grizz Bridge Rhino.

A summary of the measurements are attached in .pdf format. I apologize in that I couldn't figure out how to make this spreadsheet into a picture that I could insert here in the body of this post.

Observations from hanging the DIY bridge #1 and the Chrysalis:

1) I like the view afforded by a narrow waist (Chrysalis).
2) I like a shallower bridge as I feel there is somewhat less pressure on the shoulders (head end of Chrysalis).
3) I like my head/upper torso to be slightly higher than my feet when laying on my back, but not so much when on my side. (Will try for something between the Chrysalis and my DIY #1).
4) The Chrysalis is somewhat less tippy than my DIY.

From these measurements, I am making some assumptions and hoping that the Masters can confirm my thinking:

1) Having a smaller ratio (approaching 1) of the (fabric width/spreader length) will make for a shallower bridge.
2) Keeping the same ratio of (fabric width/spreader length) at the head and foot will make for a flatter lay. Or conversely, having a smaller ratio at the head end in comparison to the foot end, will raise the head/torso.
3) Tippiness seems multifactorial.

#3 is the one I am struggling with the most. A shallow bridge should be more tippy as your center of gravity will be higher relative to the spreader bars and the apex of your suspension triangle. This seems to be offset somewhat by having a narrower foot end (why?). Having a longer suspension triangle would seem to decrease tippiness as the apex of your suspension triangle would be slightly higher relative to your center of gravity for any given distance between trees.

Seems like I have to pick some numbers that find the happy medium:
Narrow waist, slightly shallower than DIY#1, less of a difference between head and foot than the Chrysalis, and a suspension triangle length that is as long as possible but still fits under the ridge line of my tarp.

[GrizzlyAdams]

...

Observations from hanging the DIY bridge #1 and the Chrysalis:

1) I like the view afforded by a narrow waist (Chrysalis).
2) I like a shallower bridge as I feel there is somewhat less pressure on the shoulders (head end of Chrysalis).
3) I like my head/upper torso to be slightly higher than my feet when laying on my back, but not so much when on my side. (Will try for something between the Chrysalis and my DIY #1).
4) The Chrysalis is somewhat less tippy than my DIY.

From these measurements, I am making some assumptions and hoping that the Masters can confirm my thinking:

1) Having a smaller ratio (approaching 1) of the (fabric width/spreader length) will make for a shallower bridge.

True.

2) Keeping the same ratio of (fabric width/spreader length) at the head and foot will make for a flatter lay. Or conversely, having a smaller ratio at the head end in comparison to the foot end, will raise the head/torso.

I think you want some depth at the foot end though, not as flat as at the head end...if it was really flat you'd fall out when it tipped, there'd be little there to stop you...

3) Tippiness seems multifactorial.

An understatement. Easiest thing to do is make the distance between
triangle apexes as long as you can. I did the math estimating what it would be for a hammock 78" long with suspension triangle sides the length that they are on the Chrysalis....a little over 11'.

Seems like I have to pick some numbers that find the happy medium:
Narrow waist, slightly shallower than DIY#1, less of a difference between head and foot than the Chrysalis, and a suspension triangle length that is as long as possible but still fits under the ridge line of my tarp.

I find the Chrysalis waist too narrow for my taste...YMMV....sounds to me like you're on the right track. Will be expecting a report...

[BER]

Grizz-
I was thinking about this again this afternoon.
The numbers on my spreadsheat are finished dimension for the DIY and Chrysalis. But for the Grizz Rhino, those dimensions are the cut fabric size, correct? So subtract about 2" from the cited widths to get those of the finished hammock?

[GrizzlyAdams]

Grizz-
I was thinking about this again this afternoon.
The numbers on my spreadsheat are finished dimension for the DIY and Chrysalis. But for the Grizz Rhino, those dimensions are the cut fabric size, correct? So subtract about 2" from the cited widths to get those of the finished hammock?

Had to look on your spreadsheet...54" at the head end is cut fabric size, so yes you lose a couple of inches when finished. 43" on the foot end is the width AFTER the webbing roll, e.g., when finished.

[BER]

Made corrections to the spreadsheet attached to OP to reflect Grizz's last post and added proposed measurements for DIY Bridge #2 for comparison. Measurements for DIY bridge #2: 42-30-34 with SB of 36" and 26". Makes it a little flatter than my DIY#1 at the head and a little deeper at the foot. Narrower foot end with spreader lengths similar to the Grizz Rhino. Had to decrease the side arc depth to 4" as the narrower dimensions would have made for too narrow of a waist with a 6-7" arc depth. With a fabric length of 80", I project my apex-apex length to be 133.5". Will have to remember to add ~1.5" to the dimensions when cutting the fabric to account for rolling the 3/8" webbing.

Just waiting on the polyester fabric...
Then we'll see if this works.

[GrizzlyAdams]

... Had to decrease the side arc depth to 4" as the narrower dimensions would have made for too narrow of a waist with a 6-7" arc depth.

I've been as shallow as 5", but not less than that. As you decrease the cut depth, at some point the narrower middle loses the fight against your heavier midsection and you're not flat anymore. Don't know where that point is.

Shallow cut and also narrow fabric w.r.t. spreader bar ends also up the compression forces. Ain't no free lunch anywhere....

[BER]

I've been as shallow as 5", but not less than that. As you decrease the cut depth, at some point the narrower middle loses the fight against your heavier midsection and you're not flat anymore. Don't know where that point is.

Shallow cut and also narrow fabric w.r.t. spreader bar ends also up the compression forces. Ain't no free lunch anywhere....

My thinking was that the proposed measurements on the head end, were midway between the Chrysalis and my DIY#1, while maintaining the spreader bar at 36" (for simplicity given the stock length-->I could go wider, the Chrysalis uses a 39" spreader at the head). The foot end was also a compromise between the Chrysalis and DIY#1. I arbitrarily used the same foot spreader bar as you do, but this made for a pretty narrow foot fabric width and that pushed the arc depth.

Perhaps some more thinking until the fabric arrives. At least I got smarter this time and ordered enough for two hammocks...

Thanks for all the input Grizz.

[BER]

If I go a little wider 45-30-40" using spreaders of 39 and 30", I can still maintain the ratios of (fabric width/spreader length) at the head (1.15) and foot (1.33) I was hoping for, while using a 6" arc depth. The 39" head spreader seems to hold up fine to the compression on the Chrysalis which is only 42" wide (ratio 1.07). This will push my suspension triangles a little longer, and apex to apex length of 140", but I think this will be acceptable as I have a tarp ridge line of 144".

Sorry for all of the "thinking out loud".

[BBQDad]

Looks like a swell hammock; indeed, it makes me want to try a bridge hammock.

I thought about the tippiness question. I think a ridgeline might be one possible way to get greater stability.

You could have a single ridgeline from support to support, with the hammock's spreader bars attached to the ridgeline.

I put images of two drawings showing what I mean in one of my albums.

[BER]

Looks like a swell hammock; indeed, it makes me want to try a bridge hammock.

I thought about the tippiness question. I think a ridgeline might be one possible way to get greater stability.

You could have a single ridgeline from support to support, with the hammock's spreader bars attached to the ridgeline.

I put images of two drawings showing what I mean in one of my albums.

I'm not sure if the ridge line would make a difference as shown in your drawings as I don't see it changing the axis of rotation.