Reviews > Stuff Sacks > Dry Bags > Sea To Summit Ultra-Sil Dry Sack > Ralph Ditton > Field Report

Bibbulmun Track : Sea level to 585 metres elevation (0 to 1,920 ft). Within this region I backpack along old forestry roads, sandy tracks, and purpose built walking tracks.
Temperatures  ranged during the testing period, from a minimum -4 C to 23 C (24 F to 73 F) during May to July, 2006. Overnight temperatures on average during autumn and winter ranged from -4 C to 12 C (24 F to 54 F).
Prickly Bark campsite on the Coastal Plain Trail is roughly 80 m (262 ft) elevation. It can be found at S 31°42.800' E 115°56.981'. The trail from the eastern terminus to the campsite is a sandy track that is mostly flat with a steep climb up a sand dune over the last half a kilometre (0.31 mi) to the campsite.
Shapcotts campsite at the other end of the Coastal Plain Trail is situated in a slight hollow just 7 m (23 ft) above sea level. It can be found at S 31°30.841' E 115°39.835'.
Moitch campsite is the next one along from Prickly Bark. It is at an elevation of 58 m (190 ft). It can be found at S 31° 37.419' E 115° 50.837'.
Temperatures  ranged from -5 C to 25 C (23 F to 77 F) during  May to July of 2006. Overnight temperatures on average during autumn and winter ranged from -5 C to 10 C (23 F to 50 F).
The weather was mostly wet as this is when we receive most of our rain with frequent heavy rain storms.
Snow does not occur in the areas that I hike, just heavy frost with fog.
The areas that I hike in have kangaroo ticks, huntsmen spiders and various species of snakes. Snakes in the area do not hibernate during winter as evidenced by their tracks in the sandy trails.
Field Test Information
The sack has been on four outings in my backpack.
The items stored in the sack for the first trip were my medical kit, spare socks, beanie, thermals and track suit. They filled up approximately three quarters of the sack. When I rolled down the top and did up the clip, I had a very nice handle to use. The sack slid easily into my backpack between my self-inflating mat and tent. I had to apply a little force to the top of the sack to ensure that it reached the bottom of the backpack.
At the campsite when I retrieved it from my backpack it was just a matter of grabbing the handle and pulling up. The sack slid extremely easy out from between the tent and self-inflating mat.
That night, I left the sack outside the hut on the outside table with my walking clothes, spare socks, some thermals and a gas bottle inside to test to see if any condensation formed inside the sack as the overnight temperature dropped to 4 C (39 F).

sack on the table
In the morning I examined the sack and found that a slight condensation had formed on the outside but the inside was completely dry.
What was noticeable was that the campfire smoke did adhere to the fabric and I had this stale camp smoke clinging to the fabric.  I put it back into my backpack to go home later that morning. Needless to say, the odour spread inside my pack which I found out when I got home.

The next occasion that I took the sack with me, I placed some food, utensils for cooking and some clothing. This filled the sack up. I was only able to roll down the closure three times before clipping it up. There was no other room to roll any further.
Again the sack slipped in easily into my backpack with a little downward pressure on top. The siliconised Cordura certainly makes it easy to push the sack into spaces in my backpack.
That night, I again left the sack outside my tent but with different items inside as I had eaten the food.
This night was the coldest on record for a June night according to the Bureau of Meteorology. It reached a low of -2.9 C (26.8 F) at 3.42 am. The skies were clear with light winds. The air was very dry with a low dew point. However, in the early morning just after sun up I checked the bag and found a slight covering of dew on it which had started to run in a few places.

dew running on sack
The contents were cold but dry. No moisture was detected on the inside.
At Shapcotts campsite I left the sack out  overnight on the outside table. It did rain on and off lightly during the night. Again, no moisture was detected inside the sack. The overnight temperature was around 9 C (48 F) which was quite warm for winter.
The sack received another dose of campfire smoke and this also clung to the fabric. It was not as strong as the first dose it received as this fire was lit only  for a few hours whereas the first campfire went all night.
At home I washed the sack in warm water with a solution of "NapiSan Plus" and let it soak for about a half hour.The active ingredient is Sodium Percarbonate at 25.7% w/w.(From the label).  Then I hung it on the line to dry on the outside for three hours and then turned it inside out to dry the inside. It was nearly dry inside before I turned it inside out. The smell had gone.
At Moitch campsite I pulled the sack out of my backpack by the handle that is formed by the rolling down of the fabric and clipping it together. The rolled fabric came undone although the clip was still in place. The fabric was rolled down three times along the hypalon strip. All that I can think of is that I did not roll the fabric tight enough.

rolled fabric separated from other rolled fabric
 I left the sack on the outside table of the hut with clothing and some food inside. That night the temperature fell to -4 C (24 F). Ice formed on the outside of the sack. No moisture got inside the sack but the contents were extremely cold.

ice on sack

ice particles on table
Performance against test plan
To date there are no signs of any wear or abrasions on the fabric and the buckle still works very well. The stitching is still in excellent shape.

How waterproof is the Hypalon roll top closure?
To date , no moisture has been detected inside the dry sack from condensation and light rain falling on it.

Does the stiffener at the top of the roll closure give any added advantage to waterproofing or is it just a guide for where the next fold and roll is to occur at?
It is hard to tell. In theory, the rubberized Hypalon roll top closure should exclude moisture, but I usually roll the top down a minimum of three to a maximum of six times using the stiffish Hypalon strip as a guide as to where the next roll will occur.

How transparent is the light lime green colour of the fabric?
It is reasonably good. I can see the objects that press up against the fabric and read any writing that may be on them. I can not see into the centre of the dry sack.

Can I put objects with sharpish edges in the dry sack without damaging the fabric such as my stove, freeze dry food pouches, cheese container and first aid box?
Yes. I have put all of the above in the sack at the campsites and carried the sack around by the handle as a test and there has been no damage or abrasions to the fabric.

Does the nylon buckle open and close easily?
Yes. I have no difficulty in operating the buckle.

Will the buckle fail through use?
Not to date.

Will cold temperatures cause the buckle material to become brittle?
Not apparent at this stage. The sack has spent two nights outside in temperatures below freezing with the lowest at -4 C (24 F) and the next lowest at -3 C (26 F).

On the base, is there a little reinforced pocket or strip to hold onto to pull the sack out of the backpack should it shift inside the backpack or to assist when pulling out a tight fitting item inside the sack?
No. I would recommend that a strip should be attached to the base to assist in giving leverage when extracting a tight fitting item such as a bulky item of clothing so that pulling can be done in both directions.

Does the Ultra- Sil have a high tear strength?
Not deliberately tested. My gas stove with blunt edges and serrated support arms that fold over did not damage the fabric when it was stowed in the sack.

Summary
I am extremely pleased with the sack as I have another sack to organize my gear. The sack slides in and out between other gear in my backpack relatively easily due to the nature if the siliconised Cordura.
No moisture has been detected inside the sack from the effects of either rain or condensation.
By organizing my gear into stuff dry sacks I can do away with a backpack liner and cut down  on some weight.
The Ultra-Sil dry sack is light, strong and waterproof. I especially like the way the rolled down top forms a natural handle to use when lifting the sack out of the backpack and for carrying around the campsite.
All in all, a well constructed and functional dry stuff sack.

Reviews > Stuff Sacks > Dry Bags > Sea To Summit Ultra-Sil Dry Sack > Ralph Ditton > Field Report