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Sea To Summit Ultra-Sil Dry Sacks SPOTLITE REVIEW

Lightest woven fabric dry sacks on the market today.


by Carol Crooker | 2005-08-02 03:00:00-06

Sea To Summit Ultra-Sil Dry Sacks SPOTLITE REVIEW


The Sea To Summit Ultra-Sil Dry Sacks are the lightest woven fabric dry sacks on the market, significantly lighter (by several ounces) than the Granite Gear Dry Sacks, and just lighter (by less than an ounce) than comparably sized Outdoor Research HydroLite Dry Sacks. Plastic sacks such as a mylar turkey roasting bag (0.5 oz) and the Gossamer Gear Pack Liner bags (2 mil polyethylene film, 1.3 oz for medium, 12" x 8" x 32") are lighter, but the Sea To Summit Dry Sacks still merit a look by ultralighters.

The Ultra-Sil Dry Sacks are waterproof when used as designed, according to the US marketing rep, Shelley Dunbar. She adds, "If you are going to be getting really wet, as in floating them in a river, we also recommend another layer of protection for expensive items such as cameras or GPS. They are not recommended for prolonged submersion."

I used a 20 liter Sea To Summit Dry Sack on a recent SuperUltralight canyoneering trip to protect my sleeping quilt and spare clothing in sections where I needed to swim and float the pack. I double protected my soft goods by also using a Gossamer Gear Pack Liner. Everything stayed dry.

For testing purposes, I threw the stuffed Ultra-Sil Dry Sack into a slow section of the creek towards the end of my trip. I left it floating high in the water for 20 minutes. When I removed my quilt and clothing, they were bone dry. I repeated this test with a 4-liter sack in my sink at home with the same results. In both cases, the Dry Sacks floated with the bottom seam out of the water.

The Ultra-Sil Dry Sacks are not recommended for prolonged submersion, but there are occasions when that might occur inside a pack. For example, Backpacking Light Product Review Director, Alan Dixon, recently returned from Patagonia with tales of unpacking his pack at the end of a day of wild weather to find the bottom of the pack filled with water. A dry sack in the bottom of the pack could have been partially submerged underwater for quite some time in a case like that. The Sea to Summit rep assures me that their Dry Sacks will not leak in that situation. I'm awaiting production samples to test their claim.

Sea To Summit is an Australian company making their Ultra-Sil Dry Sacks available in the US this summer. They will soon be introducing Ultra-Sil pack liners and a compression dry sack where air is released through the eVENT bottom rather than through a valve.

Use the listed volume of the Ultra-Sil Dry Sacks, rather than the listed dimensions to determine what size sack you need. According to the Shelley Dunbar, "The rule of thumb for making the dry sacks as water tight as possible is three folds, minimum." Three folds subtracts about 4 inches from the listed length of the Dry Sack, and the smaller sacks (1,2, and 4 L) are flat, rather than cylindrical, changing the volume calculation. The 4-liter size is just big enough for a lightweight synthetic insulated top, e.g. Patagonia Puffball, men's medium.

The 20-liter Dry Sack fits inside a Gossamer Gear Uberlight pack with enough room so that a folded Bozeman Mountain Works TorsoLite pad (serving as back padding), can easily be removed and replaced, such as when using the pad to float the pack through a narrow canyon section. The 20-liter Sack is over twice the volume that is needed to hold a sleeping quilt and extra hot weather clothing - big enough to hold all the contents of a sub-5-pound base weight pack for an overnight trip. Sea To Summit will soon have three oval shaped pack liners (50, 70, and 90 L)available (2.6, 3.4, and 4.4 oz respectively). The 50 liter Dry Sack should be about right for a 3000 cubic inch volume pack. Sea to Summit said there is the possibility of an extra small pack liner which would suit ultralight packs.

It is important to roll the Ultra-Sil Dry Sack top down far enough so that the pressure from the Sack contents keeps the folds in the closure tightly closed and water out.

Features and Specifications

  • Ultra-Sil nylon, a polyurethane coated Siliconized Cordura
  • Fabric is polyurethane coated with a proprietary technique to ensure the seam tape adheres and is waterproof
  • Fabric is specified to be waterproof to a hydrostatic head of 2000 mm, including the taped seams
  • Watertight, non-wicking Hypalon roll top closure with stiffener at the top for a better seal
  • The roll top closure is simple to use and neat
  • Soft and flexible with a slippery finish for easy packing
  • Nearly transparent allowing good visibility of the contents
  • All seams are double stitched and tape sealed
  • The 4 and 20-liter samples I obtained weighed exactly as advertised
Volume*Size (in x in)Weight oz (g)MSRP $
1 L6 x 90.7 (20)8.95
2 L8 x 120.8 (23)10.95
4 L9 x 150.9 (26)11.95
8 L6.5 x 181.1 (30)15.95
13 L8.5 x 211.4 (40)18.95
20 L10 x 241.8 (50)22.95
35 L12 x 272.3 (65)29.95
*Note: 50, 70, and 90 L oval shaped Ultra-Sil pack liners will be available soon.


"Sea To Summit Ultra-Sil Dry Sacks SPOTLITE REVIEW," by Carol Crooker. (ISSN 1537-0364)., 2005-08-02 03:00:00-06.