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"Going to the woods is going home, for I suppose
we came from the woods originally."

- John Muir

How Do I Stay Dry in a Hammock?

Table of Contents
  1. Choosing a Tarp
  2. Where Do I Buy a Hammock Tarp?
  3. Do-It-Yourself (DIY) Hammock Tarps
  4. How Do I Pitch a Hammock Tarp?
  5. Tarp Tricks for Hammocks
  6. End Caps
  7. Undercovers
  8. Hammock Bivy
  9. A Note About Tying to Shelters
  10. Site Selection

MacCat at Winnemucca (Trip Report)

Introduction.

Staying dry in a hammock is probably easier than in a tent or tarp because you don't have to worry about hard-packed campsites with poor drainage, dished tentsites, runoff soaking your groundcloth, or digging drainage trenches. Most people simply hang a tarp over their hammock and get all the advantages of normal tarp camping - excellent ventilation, better views, etc. Other ideas include bivies and hanging in shelters.

And the details...

Choosing a Tarp.

For something so simple, tarps actually present several options. When choosing a tarp, a hammocker must consider simple things like size, shape, weight, and price; but there are several other considerations as well. What size would you like? Will you use beaks? How about tensioners and drip strings? Will you attach it to the Hennessy connectors or directly to the tree? I'll discuss each of these below.

Where Do I Buy a Hammock Tarp?

Most camping stores sell some sort of tarp, so check out your local outfitter or stores like REI. Check online and eBay, too (search for silnylon or brand names). Better yet, support a startup, like Speer Hammocks, JacksRBetter, Outdoor Equipment Supplier, Warbonnet Outdoors, Mountain Laurel Designs, etc.

Here's a short list for comparison...prices may be dated but I'll leave them there for comparison. If you have a unique one to add, email me and I'll put it on.

Tarp Size Material Weight Cost
Hennessy Hex 144"x132" Silnylon 19 oz $130
Hennessy Hex 144"x120" PU Coated 25 oz $60
Ed Speer's Tarp 8'x10' Silnylon 13 oz $100
JacksRBetter* 8'x8' Silnylon cordura 9.4 oz $80
MacCat Standard 125"x84" Silnylon 12.5 oz $95
MacCat Deluxe 130"x104" Silnylon 15.5 oz $115
MacCat Micro 120"x62" Silnylon 7.4 oz $65
Integral Designs SilTarp2 8'x10' Silnylon 14 oz $135
Integral Designs SilPoncho* 8'x5' Silnylon 10 oz $75
Campmor* 6'x8' Silnylon 9.2 oz $55
Campmor 8'x10' Silnylon 13 oz $65
Gear Guide 9'x9' Urethane Coated 24 oz $30
Gear Guide 12'x12' Urethane Coated 31 oz $40

*Pitch diagonally

Comparison: JRB 8x8 vs MacCat Standard
I've been using my JRB 8x8 since I got it, and I'm very happy with it. When I asked Brian from Outdoor Equipment Supplier to use a picture from his page on mine, he offered to send me a tarp to test so I could review it. This is the beginning of what will eventually turn into a full review...

UPDATE: See my MacCat BGT Review and Test Details.

MacCat Standard
Photo from OES Website
JRB 8x8 with a Dusting of Snow
Hot Springs, NC

Tarp Size Material Listed Weight Measured Weight Cost
MacCat Standard 125"x84" Silnylon 12.5 oz (354 g) 13.5 oz (382 g) $95
JacksRBetter 8'x8' Silnylon cordura 9.4 oz (266 g) 10.25 oz (290 g) $80

  • The MacCat comes standard with seam-sealing, and the listed weight reflects this.
  • The JRB does not come seam-sealed, so the listed weight does not include it.
  • The MacCat comes with a stuff sack; the JRB does not.
Quality. This is tough to compare because both tarps are high-quality pieces of lightweight gear. I noticed a few irregular stitches on both, but that's the only "defect"...it's tough to sew such light material, and the stitches certainly won't affect functionality. The JRB is of excellent quality, but the MacCat I received looks like it's a little bit higher quality workmanship, and the grosgrain trim and webbing at the guyline connections make the tarp appear to be more durable. Brian says the trim improves the strength of the tarp (especially important if it's whipping in the wind during setup) and provides a nice finished appearance. It also makes sewing the silnylon easier, reducing irregular stitches. I'm sure the trim strengthens the edges, and it sure looks nicer, but I'm not convinced that much strength is needed for a lightweight tarp. It only adds ~1.5 oz total to the tarp, and he doesn't need a complete rolled seam underneath, so I'm guessing it adds just under an ounce to the weight.

Shape. The major difference between the tarps is the shape. The JRB is a square, pitched diagonally, so you only need two stakes (and cord) to set it up. The MacCat is a hex with a straight ridgeline and catenary sides. This shape removes the extra material that causes rectangular tarps to sag and flap in the wind, resulting in a MacCat that's very easy to get a nice tight pitch. Since the ridgeline is straight, the tarp doesn't have an "optimal pitch angle" that catenary ridgelines can cause, which means more flexibility for the user while maintaining the advantages of the cat cut.

Another major impact of the shape is that the MacCat requires four stakes with cord rather than the two for the JRB. This adds a bit to the weight and increases setup time. In some cases, it may reduce campsite options.

In the beginning, I thought the MacCat would provide better protection on the ends, which is the only place I've experienced any problems with windblown rain in a hammock. After setting them up together, though, I'm not sure that's the case. The JRB is about 2" longer on the ridgeline, and that seems to make up for the difference. You can see in the picture below that the MacCat is pretty far away from the hammock before the coverage increases. I think this will provide more useful coverage under the tarp (vs the corners of the JRB, which is really too small to use for anything), but not necessarily better end protection. I'll test this more when Monterey gets it rainy season!

Guyline Connectors. Another big difference is the guyline connections. JRB uses nylon loops...very light and functional. I just use a clove hitch for my guylines and it attaches perfectly. The MacCat uses thicker webbing to attach plastic D-rings to the tarp. A clove hitch still provides enough friction to hold the guylines to the tarp. I think the D-rings will be more durable than the JRB's nylon, but after more than a year of use I haven't noticed any significant wear on the JRB's loops. Again, I'm not sure the extra weight is needed, but it's probably only a few grams difference. I'm NOT going to take apart the tarps to measure it!

Guyline Connectors: MacCat Standard
Guyline Connectors: JRB 8x8

Headroom and Ventilation. This is a major advantage of the MacCat over the JRB. The JRB uses the diagonal shape to approximate a cat cut, and it works well. When I set it up tight, the corner tie-outs pull the tarp down in the middle, approximating the catenary and reducing extra flapping material. However, I can't really get a tight pitch without pulling the center down, which really reduces headroom inside. I didn't notice this made much of a difference until I took the picture below. The MacCat sits about 7" higher in the middle than the JRB when pitched for approximately the same type of coverage. Extended along the rest of the ridgeline, this makes quite a difference in how big the tarp "feels" inside.

When I use my homemade Speer-types, I often brush my back on the underside of the JRB because it sits so low, but pitching it higher would decrease the coverage. The MacCat makes it easier to get in and out without brushing the tarp...especially useful when condensation is on the underside of the tarp. I think the extra space will also improve ventilation, which will further decrease condensation.

JRB 8x8 under the MacCat Standard
Note the difference in headroom

Interim Conclusions. In sum, both of these tarps are very light, high quality pieces of gear. The JRB is a bit lighter,* but the MacCat appears more durable. The JRB is easier to pitch, but the MacCat seems to provide more usable space inside and be more comfortable overall.

Which would I choose if forced to bring only one? I can't say at this point...they're both awesome, and I need more testing to decide. Keep in mind, this is only a preliminary report...I'll keep updating as I get more field use with the MacCat.

UPDATE: I used the MacCat on my Ten Lakes trip in Yosemite. It seemed to cut the wind better than the JRB, but it wasn't very windy so I don't want to be too hasty in drawing that conclusion. I certainly noticed the extra space, though tying the two extra guylines added a bit to the time and hassle-factor. I was fully satisfied with the MacCat on this trip!

See the Ten Lakes Pictures and Cold Weather Test for more details of the trip.

Do-It-Yourself Hammock Tarps

A basic rectangular tarp is pretty easy to make...if you can make a straight seam on silnylon, you can make a tarp. Ed Speer has simple directions in his Hammock Camping book, and a rectangular hammock tarp is basically the same thing as in Ray Jardine's Beyond Backpacking.

Blackbishop made a great catenary hex tarp based on the MacCat and posted very clear directions online so you can make your own. Gunn Parker hosts a page where you can find the .pdf file of the BlackCat DIY Instructions. Use Adobe Acrobat to view the .pdf file. Here's a backup link. It also has pictures of him using a cat tarp on the ground.

FanaticFringer's BlackCat
Photo by Blackbishop

BlackCat (~14 oz) vs JRB (~10 oz)
Photo by Blackbishop

DIY Catenary Tarp
Photo by Hammock Engineer

One great thing about DIY gear is that you can make it to address your own needs, and you get things that aren't made commercially yet. GrizzlyAdams wanted more room for his bridge hammock, so he made the quonset hut pictured below. Hammock tarps didn't have doors until some DIYers added them to existing tarps...now you can get the Warbonnet SuperFly and the JRB Hammock Hut, and a few winter tarps that approximate the end coverage of doors when pitched right.

GrizzlyAdam's Quonset Hut at Mt Rogers
Photo from Hammock Forums

How Do I Pitch a Hammock Tarp?

Tarp Tricks for Hammocks.

End Caps.

  • Slowhike created End Caps that go on the hammock instead of on the tarp...not only do they protect the ends of the hammock, but his second version also provides a place to store gear. Easy to reach and the gear stays off the muddy ground. (Look inside the end cap, under the hammock, in the pic below.) He also adds a small gear hammock at the head end, inside the end cap, for flashlight, water, etc.

    Add a drawstring and they can also be stuff sacks to store the hammock in...like a Blackbishop Sack, only bigger.

    Slowhike's End Caps, Version 1
    Photo by Slowhike

    Slowhike's Storage End Caps
    Photo by Slowhike

    Small Gear Hammock in Storage End Caps
    Photo by Slowhike

  • Undercovers.

    Sometimes thick fog rolls in and soaks everything under the tarp, including the hammock, underquilts, and even the underside of the tarp itself. Other times, windblown rain and spray soaks the hammock and underquilt, especially near the foot end if a rectangular tarp is not used. However, using a waterproof undercover can help. A simple silnylon Garlington Taco can keep the fog off of the bottom-side insulation.

    I reviewed the JRB Weathershield, which is a 100% waterproof, breathable undercover made from microporous polypropylene, like the Frogg Toggs material. Designed for the Hennessy Hammock and to protect the JRB underquilts, it can be used with no insulation, with your own insulation, or with the JRB quilts. It'll add 6-10F of warmth and keep the hammock and insulation dry. JRB also makes a Weathershield for a top quilt.

    See the Hammock Camping Warm page for more details on undercovers.

    JRB WeatherShield on a Hennessy

    Hammock Bivies.

    I've looked for other ways to stay dry without using a tarp. I like to sleep under the stars, but I don't want to risk my down bag getting wet when the bottom drops out of the sky before I can get my tarp up. Also, in some areas the fog rolls in sideways so you get wet under your tarp anyway. I made my Hammock Sock as a prototype hammock bivy...it's just DWR so it wets through pretty easily, but it keeps me warmer, too.

    DebW made her hammock bivy out of Epic...it's waterproof/breathable and it looks awesome! I bet it keeps her warmer, but I'm not sure how waterproof the opening is. I first saw it on Whiteblaze.net in the hammock camping photos section, then I noticed it was in the Yahoo Group photos section, too.

    DebW's Hammock Bivy
    Photo by DebW

    A Note About Tying to a Shelter.

    A hammock exerts about 600lbs of force on each rope...that's a lot of force for a rickety old shelter to handle. If you're in a reinforced pavilion you'll probably be ok...just be careful in something like an AT shelter. Be especially careful if you tie off to any structural members...you might bring the whole shelter down! In the Files section of the Yahoo! Hammockcamping group, Youngblood has posted an Excel spreadsheet illustrating the forces a hammock support exerts. Basically, the support rope is the hypoteneus of a triangle. Using the angle of the hammock support to true horizontal, calculate the force on the support (h) by

    h = (.5 x user weight) / sin(support angle)

    Site Selection.

    Just like staying warm, site selection is one of the most important factors in staying comfortable and dry in your hammock. Read the section in Staying Warm for details.

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