Jay Ham’s Cut Down Thermarest

I have a thermarest ridgeRest pad that i used to use with my GoLite Breeze.

Simply cut it down to the desired length to reduce the weight by cutting the desired number of inches off of the foot end of the pad by cutting straight across the pad.

The “cut-down” is not a vertical/thickness cut-down. It is a length cut-down.

Furthermore, you could also reduce the wt. a little bit further, by cutting a “mummy” type of shape off of the remaining rectangular pad. That is, cut the four rectangular corners off the remaining pad, which was just previously cut-down to a shorter length, by making angular cuts. I know this description is NOT very clear, so go to the POE website & look at their pads – they come mfr’d with that “mummy” cut shape.

You can weight the end result (the best way to determine the wt) or if you leave it in a rectangular, non-mummy shape, it’s a simple linear calculation to calculate the wt. of the cut down pad.

e.g., using a standard ridgerest’s published figure

14oz*new-length-in-inches/72inches =new wt.

conversely, you could work the equation backwards, picking a new “target” wt & then solve the equation algebraicly for the “new length”.

According to the article, Jay had cut down and old style Therm-a-Rest UltraLight 3/4.

Isn’t the 10 oz BMW TorsoLite sold on BPL (www.backpackinglight.com/cgi-bin/backpackinglight/torsolite_inflatable_sleeping_pad.html?id=XbWVX8pm:12.75.221.190) almost the equivalent to a self inflating Thermarest Matress with a surface and inner foam similar to the older UltraLight (instead of the newer Prolite 3 and 4)? Though presently out of stock, a members price of $58.79, and if you can deal with the 32″ length this may be the way to go.

I had a ridge rest but just couldn’t get comfortable on it (or foam pads in general).

I just recently purchased the torsolite pad and have used it a couple of times. I also have a prolite 3 Short. The Torsolite is comfortable and compared to the thermarest seems more durable (shell material) and the foam firmer, probably due to the less aggressive die cut foam compared to the thermarest.

However, the 3/4 length thermarest is only 3 oz heavier than the torsolite but considerably larger. On a “per length basis” it’s lighter (and I would imagine less durable and colder).

Still, I was thinking a prolite 3 cut down to the torsolite’s dimensions would be a bit lighter, maybe in the 8 oz range.

Cheers
Dan

Hi Dan,

Personally in a previous generation of the 3/4 Ultralight Thermarest, I found the pad a little uncomfortable due to the thickness (1″). That is partly why I purchased a Prolite 4 3/4 length Thermarest. The Prolite 4 3/4 is thicker (1 1/2″) and more comfortable, (but another 3 oz heavier) than the Prolite 3 3/4.

You are correct about the surface of the newer Prolite Series are not as rugged and because of the more aggressive die cut foam of the Prolite 3 and 4 are not as firm or as warm (have a lower R value) as the older Ultralight and Guidelight Pads that they replaced.

Another reason I had purchased the Prolite 4 3/4 when the Ultralight 3/4 were being cleared out was it was 1 oz heavier, thicker with what may have been a higher R value than the Ultralight.

The cut down Thermarest mentioned in Carol’s article was a 3/4 length Thermarest UL purchased on-sale ($35) just as the Prolite pads were hitting the market. I wanted a pad that was lighter and shorter, but the standard width to fit in UL packs that incorporate your sleep pad for the frame; specifically the Starlite and Mariposa.

I cut the pad down and resealed it. The real trick is getting the pad to reseal and not melting the fabric. The open cell foam inside is adhered to the fabric and prevents the fabric from resealing unless it is completely removed. I have some pieces of older and newer Thermarest pad that I am experimenting with to see if my resealing technique works universally or not. Look for a Make Your Own Gear article on it in a few months.

The Torsolite is a great option. Even though my wider, cut-down Thermarest weighs about the same, the Torsolite is actually a bit more comfortable and durable. It works fine in the Mariposa, but not so well in the Starlite.

Jay Ham

I experimented with cutting down a Thermarest before buying a Torsolite. I used the heat bond glue that thermarest sells in repair kits. After several attempts (and purchases of more repair kits) I couldn’t get it to be 100% airtight. As I found out about 2 am the last time I tried to use it. The repair kit instructions suggest using the pot that you used to warm up the glue as an “iron” to smooth out the seam. It was hard to get a consistent straight seam with the curved pot edge. I tried an electric iron protected by tin foil but it didn’t work very well. (I also kept thinking how I was going to explain getting glue all over my wife’s iron…) When done right the glue works-it’s just devilish hard to apply consistently along a long seam. I would finish the job, find a pin hole leak by testing in water-then reapply heat to seal the leak-only to open up the seam for a 3 inch section. Much cursing would result. I decided it was time to pay someone to make a better inflatable pad.

Jay,

thanks for clarifying for me (& everyone else). have never seen this pad. sounds like a bit of work to modify it as you did. you must have done a good job since it isn’t springing any leaks on (under) you.

Daniel,

sorry to have confused the issue for you.

I would agree with a prev. poster that the BMW TorsoLite is a much more robust & comfortable self-inflating pad than the ProLite3. IMHO, there is no comparison b/t the two pads. However, three of my co-workers love the Prolite3 however (one of them bought mine). The robustness & comfort of the Torsolite comes at a expense of some wt. though (i.e. wt given its size, not its absolute wt.).

So, how many ounces is a good night’s sleep worth? I’ll take the good night sleep over a few ounces saved.

For those interested in resealing a ThermaRest, we’re pushing ahead with the Thermarest reshaping article. It’s in the hands of BPL’s editorial staff to be published late August/early September. Oh, and I tested my technique on some Prolite 3 samples. The results are in the article.

Jay
BPL