Field Report: Therm-a-Rest ProLite 4 Short Pad

Tester:  Rosaleen Sullivan

Age:  54 years

Gender:  Female

Height:  5’ 9” / 1.75 m

Weight:  190 lb / 86 kg

E-mail:  rosaleen43 (at) aol (dot) com

Home:  Eastern MA, USA

Date:  April 21, 2004

Tester Background

I have done family car camping from my childhood, using many shelters from a tarp through a travel trailer. The backpacking bug bit when I went along as a driver/chaperone for my oldest son’s Boy Scout Troop. After learning to backpack by the old Troop methods, I decided about age 50 that there had to be a better way. I’m gradually lightening up, and I do most of my hiking and backpacking during weekends in New England. Additionally, I have been lucky enough to experience hiking to the bottom of the Grand Canyon and a 110 mile (177 kin) stretch of the Appalachian Trail from Pennsylvania to northern Virginia. My preferred gear at this time is a Hennessy Hammock for shelter, an alcohol or solid fuel stove, home-dehydrated foods requiring minimal preparation and cooking on the trail, and the least amount of additional clothing and gear that I can feel comfortable carrying.

Product Information

Manufacturer:  Therm-a-Rest

URL:  http://www.thermarest.com

Year of Manufacture:  2004

MSRP:  about $80.00 USD

Listed Weight: 17 oz (482 g)

Weight as Delivered:  15.5 oz (438 g) weighed on an electronic scale

Product Description (Slightly updated from the Initial Report)

The Therm-a-Rest ProLite series is a group of self-inflating camping mattresses.  Within the family, there are choices in widths, lengths, and thicknesses.  The ProLite 4 is the thickest.  I have chosen the short model in the narrower of the two available widths in order to maximize padding while still minimizing weight.  The ProLite 4 (S) measures 20 x 47 in (51 x 119 cm), by about 1.5 in (4 cm) thick, and, at 15.5 oz (438 g), weighs just under a pound (about 230 g).  The top surface of the mattress is orange urethane coated polyester fabric with a grid or “ripstop” look, while the bottom is urethane coated nylon.  The top material is translucent enough that the die cutouts in the middle layer of open cell urethane foam are visible.   The mattress has a black plastic twist valve that maintains inflation or deflation.   It was initially a bit hard to turn, but it has given me no further problems. This mattress also has rounded corners and does not appear to be “tapered.” Maybe tapering is more evident in the longer models. 

Product Performance in Field Testing

The two functions I usually expect from any mattress are comfort and insulation from cold.  I have tried the ProLite mostly in my hammock, where I need some insulation in colder temperatures.  In temperatures from the mid 20’s to about 50 F (approximately -7 to 10 C), the ProLite has provided excellent insulation.  It is, of course, not quite wide enough to provide insulation for my arms.  For cool to cold nights, I usually plan on an under hammock mylar blanket, or a foam and aluminum windshield reflector.  These at least deflect some wind from carrying off heat.   The mattress adds both insulation and a bit more “cush” to an already comfortable hammock.  I could definitely feel cold where I didn’t have the mattress under me, until I added some clothing or other padding between myself and the bare hammock bottom. 

In addition to using the mattress in my hammock, I tested it on a wooden platform and on the ground.  I mentioned in my Initial Report that I could have been the inspiration for “The Princess and the Pea.”  On a wooden platform, as one might find in a shelter, the Prolite was not enough padding for me.  I could not get comfortable until I slid an inflatable vinyl mattress under it.  I thought the temperatures were predicted to be about 18 F (-8 C) that particular night and found that while I was warm from my underside, I was not warm enough and I bailed on that experiment when I started to shake.  I later found out the temperature was about 12 F  (-11 C).  That is way too cold for me or my sleeping bag rating.   Retrospectively, I wonder if my tolerance of the ProLite on a wooden platform is dictated by how bad my chronic back spasms are on a given night.  I will try wooden platforms again during the Long Term testing.   I have tried short naps using the mattress on top of a groundcloth over undisturbed forest duff.  I think this could work for me.  The ground seems more forgiving than a wooden platform.  With adjusting the amount of air in the mattress and my side sleeping position a bit, or placing a jacket, my pack, or a bag of extra clothing under my legs for back sleeping, I was actually comfortable.  This also deserves some further testing in the next few months.  Again, the mattress seemed to be enough insulation from the cold surfaces below me.

I have yet to examine the ProLite’s water resistance.  It hasn’t seemed to pick up any dampness as I’ve slept on it, but we are still in winter to early spring, seasonally.  It has been cold enough that I’ve mostly slept in thermal underwear, fleece, or even a down jacket and pants.  I will be interested to see how the mattress reacts to sweat in the summertime.  Will it absorb sweat and get heavier, develop an odor, mildew, stain, or other unpleasant outcome?  Will it dry quickly?

One issue with any mattress on the slick nylon of many tent and hammock bottoms can be whether or not the mattress slips as the user moves.  The manufacturer has “textured” the mattress bottom with small raised dots.  I find the dots do not appear to have much effect.  If I rolled over on the mattress, especially wearing a napped fabric such as fleece, the mattress moved with me instead of staying put.  I did slip a piece of rubber “gripper” material, such as a form of shelf  lining and found that this helped a good deal.  I should think to weigh that piece of gripper material.  The mattress weighs less on my scale than the manufacturer claims.  I may have "found" that lost weight!  Rats! 

In our quest to lighten packs, some of us use our sleeping pad to pad and give support to backpacks.  I used the folded ProLite as the padding and spine in a frameless pack for about 18 miles (29 km) of the Appalachian Trail  and was satisfied.  I think a key is to leave some air in the mattress.  Better yet may be to get one’s gear packed, and then add a few puffs to the mattress, stopping when the desired rigidity is reached.  The shelf  liner material I used to keep the mattress in place as I slept helped keep the mattress in place inside the pack, as well.

Test Locations and Further Plans

I have used the ProLite in my yard, local trails, and a long weekend on the Appalachian Trail in Massachusetts.  I intend to continue to experiment locally and on the Midstate Trail in central Massachusetts, the Appalachian Trail in New England, and in Yellowstone Park in Wyoming this summer.  Temperatures easily could range from the mid 90’s to the 30’s F (about 32-0 C).  I plan to continue with using the pad in my hammock, on the ground under a tarp or in a tent, and, possibly, on wooden platforms.  I will continue to look for signs of wear, how the valve holds up, and if the mattress inflates differently at the higher elevations of Wyoming’s Rockies compared to sea level.

Likes So Far

Cushy

Very light

Easy to inflate and deflate

Good insulator

Dislikes So Far

Slips around in use/bottom needs more tack    

Not always enough cushioning.  (There may be no such thing for me.)

            Not always long or wide enough.  (My decision was to go with this pad instead of the larger ones, based on weight.  This dislike is not the pad’s fault!)

Respectfully submitted,

Rosaleen Sullivan