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

I have been walking the Bibbulmun Track in sections over four years. My goal is to complete the 964 km (603 mi) and become an end to end walker. So far I have completed approximately two-thirds of the Track from North to South, and a quarter in the opposite direction. I have evolved from carrying a heavyweight load -- approximately 28 kg (62 lb) including food and water--to being a midweight backpacker, averaging 18 kg (38 lb) at the start of a trip. My trips are usually between three to five days duration.

Product Information

Manufacturer: Sea to Summit.
Manufacturer's Web site: http://www.seatosummit.com.au
Made in: China.
Year of Manufacturer: 2006
Model: 13 Litres (793 cu in)
Fabric: Siliconised Cordura
Colour: Light Lime Green
Weight: 40 g (1.41 oz)
Size: 53 cm x 31 cm (21 in x 12 in)
MSRP: Not stated.

My Measurements
Weight with storage packet: 61 g (2.2 oz)
Weight without storage packet: 40 g (1.41 oz)
Size: 53 cm x 31 cm (21 in x 12 in)
Length: 52 cm (20.5 in)
Width of Hypalon roll top closure: 2 cm (0.79 in)


Ultra-Sil dry sack

Expectations from the web site
The photos of the three different coloured sacks on the web page gave me a very good indication of what to expect. The seven different sizes of the sacks did not have the colours beside them so I was unsure of what colour I was going to receive.
The weight was spot on with my measurement using the local Post Office scales.
The only difference that I noticed was that the web site has the 13 L (793 cu in) sack size measured at 53 cm x 21.6 cm ( 21 in x 8.5 in). In actual fact, the packet has 53 cm x 31 cm (21 in x 12 in) which I verified. The base is 53 cm (21 in) and the top opening is the 31 cm (12 in).
There is a difference of 9.4 cm (3½ in) for the top opening.

measurements on packet

Product Description
The Ultra-Sil Dry Sack is an ultra lightweight, waterproof storage bag. It is made from Siliconised Cordura with tape sealed double stitched seams. Waterproofing has been achieved by applying a coating of Polyurethane.
The base is round.
To close the sack I have to expel any excess air by pushing the sides near the top together, roll the Hypalon closure band down three to four times then clip the buckle together. If I do not expel the excess air, I can not squeeze it out through the fabric when the top is rolled down as the fabric is also air tight.
The manufacturer states that the sack is designed to keep the contents dry in any situation that the sack is not submerged.

sack closed
The buckle is nylon and has two prongs that slide and lock into the female component. On the buckle is stamped UTX-FLEX. To open the buckle, I squeeze the two prongs inwards so that they slide out of the locking position when I pull gently on it.
The fabric is relatively transparent which enables me to see inside the sack.

Initial Impressions
As I am familiar with the Sea to Summit packaging, the long thin container  enveloping the sack was consistent with their style.

packaging container
There are dot points of the features on the reverse in English, German, French, Spanish and Japanese.
I was impressed with the sticker on the front stating that the item was the Editors' choice 2006 Backpacker which means that the company was presented with the prestigious Backpacker Magazine Editor's Choice Award for the Ultra-Sil Dry Sack and Pack liner at Salt Lake City, Utah in January, 2006.
Extracting the sack from the envelope I was immediately surprised by the stiffness of the roll down top. One side is completely stiff with a stiffener sewn in the collar, and the other side quite flexible with a Hypalon fabric sewn on the outside of the siliconised cordura to make a watertight closure when rolled down. (see photo below).The Hypalon smells like rubber. The stiffener really surprised me as I was expecting both sides to be soft with a hook and loop system being employed inside the collar.

 Hypalon closure
Enclosed with the sack was an instruction card in six languages, English, German, French, Spanish, Japanese and Dutch.
The instructions state that the sack is ideal for keeping contents dry.
To close, ensure that all excess air is expelled, align the two top edges and roll down at least three times before closing the buckle to secure the sack.
There are care and cleaning instructions which is a nice change to see incorporated with the instructions.
The sack must be stored dry, avoid abrasions.
The sack must not be washed in detergent or hot water. No bleach is to be used nor left in direct sunlight for an extended time.
I filled the sack with some items to see how it looked and if I could see items inside it.
There is no sewn on strip of material on the base of the sack to assist with pulling it out of a backpack should it move when unpacking the backpack. However, the rolldown top can form a handle to lift out of a backpack and also to carry around camp say to a table when I want something out of it.

handle formed by roll top closure
I was able to see through the fabric to ascertain by and large what was in it. The items on the outside hid items in the middle as the sack was reasonably full and I did not want to shake it around to see what was hidden. My medical kit showed up quite clearly nd I was able to read some of the contents that were against the side.

lettering of medical kit seen through the fabric

To place the sack back into the envelope, I find it easier to roll it up from the base as this expels the air as I roll it up. When I did it from the top down, the air could not be expelled through the fabric due to the waterproof coating.

Test Plan

As I currently own a 4 litre and a 9 litre Siliconised Cordura Sn240 Stuff Sack weighing 13 gm and 21 gm respectively, and made by Sea to Summit, I am familiar with the material and its uses.

In addition,I currently use a Sea to Summit tough, double coated heavy duty nylon and heat sealed tape seams with a roll down watertight closure,  110 litre pack liner to place all of my gear in.

Due to the weight of the pack liner some 310 g ( 11 oz), I am considering doing away with it and substituting a number of the Sea to Summit Sn240 stuff sacks and Dry sacks. 

To date I have been impressed with the use I get out of and water repellent features of Sn240.

What I will be looking for will be the following:

• How secure is the nylon buckle?
• How waterproof is the Hypalon roll top closure?
• 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.?
• How transparent are the various colours? From the web site there appears to be only three colours available, red, lime and blue. The colour that I have is grey and it is very transparent which allows me to see what I have in each bag without tipping the contents out to find an item. Will this be a problem with the other colours?
• 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 kit box?
•  Does the nylon buckle open and close easily?
• Will the buckle fail through use?
• Will cold temperatures cause the buckle material to become brittle?
• On the base, is there a little reinforced pocket to hold onto to pull the sack out of the backpack should it shift inside the backpack?
• Does the Ultra-Sil have a high tear strength?
• Does the Ultra-Sil keep moisture from entering the sack and wetting the contents?
• Conversely, if I place my wet, dirty clothing in the sack, will the moisture transfer to the outside surface and wet other items that are in contact with the sack?

• The sack is lightweight
•  colourful
• transparent to a degree
• collar rolls down easily
• buckle is easy to open and close
• roll down closure can act as a handle

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