How to get more width for a tarp....

Wow, that's some serious width. And I am someone who likes big tarps. The extra seams would add some weight though. With them being low to the ground and not overheard, I wouldn't worry about seam sealing them.

Oh and it was Sit Mix Alot, and not MC Hammer.

Quote:

---

Originally Posted by hammock engineer

Wow, that's some serious width. And I am someone who likes big tarps. The extra seams would add some weight though. With them being low to the ground and not overheard, I wouldn't worry about seam sealing them.

Oh and it was Sit Mix Alot, and not MC Hammer.

---

OOps showing my age a bit there... LOL! My bad for getting the artist mixed up.

Schrochem, It depends on the geometry you're using, but for mine or something similar about 6" of coverage. I haven't decided if its worth the hassle or not.

Quote:

---

Originally Posted by Rapt

Not really....

If you use a "hex" design that's material you'd just throw aside as scrap. Instead you attach it to the edges... Like I mentioned with the BlackCat standard dimensions you cut off a triangle with a 34" base and a 66" height. This is material you could maybe use on another project, or to make a stuff sack, but it wasn't going on your tarp... Now it is.

There are already things that show a hex tarp has more coverage than a square for a given ridgeline length. Such as this photo by Blackbishop http://www.tothewoods.net/ImagesStay...ackCat-JRB.JPG

In my case I wanted a 14' ridgeline, but to get a reasonable angle so I'd have a taut pitch I couldn't make the sides between the tie-outs much longer than 9'. That still gives more end coverage than a square. But the length difference meant I was cutting off a triangle 30" at the base by 60" high. This way I can add them to those sides and gain most of that back, instead of wasting it.

Giving me a tarp that can either be pitched wider and flatter with more area under it, or higher and narrower with better side coverage and headroom.




:p I was wondering what to call it...

---

Note that this is a Black Cat which is some 30 percent larger than a MacCat...It is very close to a 12x10 that has been reshaped to provide a wide angle hex with cat edges. It is on the order of 100 sq ft and 16-18 oz or so.... It is compared here to an 8x8 with approximately 60 sq ft of coverage for 9 oz.

The unshown relationship is that the 8x8 is a actually the same or larger than a standard Mac Cat, just a slightly different shape . And that both the 8x8 and the MacCat are 30 percent larger than a standad BULA tarp.

All three tarps discussed here provide more than adequate coverage.... The real issue is, how much extra room would you like and at what cost in $ and weight.

FWIW, while we are on this point, it is fair to note that for any given size, the traditional rectange provides more coverage, more flexibility in pitch options and frequently weight LESS that the Cat Hexes because rectangles with rolled hems eliminate the weight of the gross grain tape commonly used to edge this design. They also are normally less costly.

Further, it is worth noting that the emerging rectangular tarps with mild cat cuts , like the Speer 8x10, may be the best of both worlds. Max coverage, less weight, more versatility, taut pitch and approximately equal cost for equivalent length sizes. So if you are into max coverage, taut pitch and less weight for a given ridge length consider these emergent cat rectangles.

Pan

What do you guys think of the Gosamer tarp?

http://www.gossamergear.com/cgi-bin/...inn-Twinn.html

It looks like it might be a bit short for a hammock at 117".

Quote:

---

Originally Posted by Dutch

I really call it a rain skirt around most circles. Actually I really like mine and I am trying to figure out a way to turn it into a weather shield for the end of my tarp or my bridge hammock. It should be a piece of cake since it is just a rectangle with elastic and a couple buttons. I don't usually dress in drag in the woods, but I can't hike in rain pants and the skirt, errr kilt weighs nothing and keeps my bum dry.

---

You might try replacing the elastic with a draw string.

Pan,

Love to talk more about about "coverage". Everyone has different perspectives. From my point of view and experience with the conditions I typically camp in (down bag, windy driving rain, temperature swings, solo - as in no other people for days/weeks in any direction) And the things I've survived, but wasn't comfortable with or happy about at the time. I'm not comfortable having less than a LOT of margin when it comes to keeping dry.

A diagonal pitched square is to my mind "less" effective because your ground coverage is MUCH smaller since there are no long sides near the ground. Granted I know that this is a hammock forum, but we still walk and cook and store many things on the ground even if we sleep and sometimes sit in a hammock. I like to be able to do things when its raining, but still have someplace to get out of the rain without being in bed. A hex seems to suit this compromise by giving longer coverage for the hammock but still "longish" sides close to ground for when you're NOT in the hammock.

Oh and my hammock has an 11' ridgeline... Maybe I need to make a shorter one...

I'll carry weight if I have to, to acheive that., I'd prefer not to, so things like Cuben seem appealing to let me go big AND still be light.

I'll dig into squares (and rectangles) vs hexes and do some overlays...

Having spent some time thinking, and doing some math, I can state that a hex of a set area gives better "effective" coverage than a rectangle of the same area, provided the material from cutting the end angles is used to extend the width.

In doing the math I made some assumptions. 1)The ridgeline length is the same in both cases, for example if a 14' ridgeline is required and fabric is 60" wide for a maximum rectangular area of 14 x10' 2) the hex would be 14' ridgeline with an approximately 12.5' width and 8' parallel to the ground on the sides, (actually this shortchanges the hex by about 1.8%, but as we'll see its still better. 2) The ridgeline pitch height is the same in both cases. 3) The low sides are pitched the same vertical distance from the ground.

For example... Assume a 5' ridgeline pitch height and the low sides are 1' off the ground (Not too unreasonable I think for a windy rainy pitch.)

The covered area of the 14 x 10 rectangle is: using Pythagoras to get 3' per side 6*14= 84 sq ft. Not bad and you probably won't rub against the tarp sides with the hammock with such a steep pitch....

BUT using the hex as described above and Pythagoras the width is 4.8' per side. The area is 8*9.6 (for the long sides) + 3*9.6 (for the hex points at each end) = 105.6 sq ft Clearly better with the tapered ends giving less coverage where the hammock is higher off the ground. Not to mention the greater width ensuring that its very unlikely the hammock will touch the tarp.

As a side note a 10' x10' square is clearly less in area (about 30%) but pitched diagonally has pretty close a 14' ridgeline. At a diagonal, the above pitch gives the following: 5.75' per side of coverage distance or an area of
11.5*7 = 80.5 sq ft. This is clearly less than both the above, but not a lot less considering the difference in weight for 100 sq ft vs 140 sq ft of fabric. The only thing is without any "long side" near the ground there is much less lateral coverage with windblown rain.

Convenience in pitching, flexibility, tautness, etc, are less easily compared since they have a large subjective content. But I think that its likely that a rectangle 14 x10 will require at least as many tie outs as the hex to remain taut. The square saves a couple of tie outs...

All in all I think I'll stick with the hex...

Quote:

---

Originally Posted by Rapt

Having spent some time thinking, and doing some math, I can state that a hex of a set area gives better "effective" coverage than a rectangle of the same area, provided the material from cutting the end angles is used to extend the width.

In doing the math I made some assumptions. 1)The ridgeline length is the same in both cases, for example if a 14' ridgeline is required and fabric is 60" wide for a maximum rectangular area of 14 x10' 2) the hex would be 14' ridgeline with an approximately 12.5' width and 8' parallel to the ground on the sides, (actually this shortchanges the hex by about 1.8%, but as we'll see its still better. 2) The ridgeline pitch height is the same in both cases. 3) The low sides are pitched the same vertical distance from the ground.

For example... Assume a 5' ridgeline pitch height and the low sides are 1' off the ground (Not too unreasonable I think for a windy rainy pitch.)

The covered area of the 14 x 10 rectangle is: using Pythagoras to get 3' per side 6*14= 84 sq ft. Not bad and you probably won't rub against the tarp sides with the hammock with such a steep pitch....

BUT using the hex as described above and Pythagoras the width is 4.8' per side. The area is 8*9.6 (for the long sides) + 3*9.6 (for the hex points at each end) = 105.6 sq ft Clearly better with the tapered ends giving less coverage where the hammock is higher off the ground. Not to mention the greater width ensuring that its very unlikely the hammock will touch the tarp.

As a side note a 10' x10' square is clearly less in area (about 30%) but pitched diagonally has pretty close a 14' ridgeline. At a diagonal, the above pitch gives the following: 5.75' per side of coverage distance or an area of
11.5*7 = 80.5 sq ft. This is clearly less than both the above, but not a lot less considering the difference in weight for 100 sq ft vs 140 sq ft of fabric. The only thing is without any "long side" near the ground there is much less lateral coverage with windblown rain.

Convenience in pitching, flexibility, tautness, etc, are less easily compared since they have a large subjective content. But I think that its likely that a rectangle 14 x10 will require at least as many tie outs as the hex to remain taut. The square saves a couple of tie outs...

All in all I think I'll stick with the hex...

---

you want I should see if Sister Mary Augustine is around to check your figures? ;)

Grizz

If you're wrong she'll rap your knuckles with a ruler.

Sure... I think I did it right... But most of it was in my head so I may have missed something, or doubled when I should have halved or vice versa...:D