I have owned numerous cags, semi-dry cags, dry cags and dry suits over the years. Neoprene seals, latex seals – all have been tried and tested for years and in reality none have ever been 100% dry.
At the end of the day I believe that it’s all relative, if the cag fits right and the seals are constructed or even trimmed to give a good water tight seal you will only ever minimise the chance of water finding its way inside. In some cases the amount of water entering the cag is so small it is virtually dry, but will never be totally dry.
Personally I find that I always get a little water entering the neck seal. Not piles of of water just the odd drip and this has always been the case. I think this is down to the way the seal sits on my neck as I paddle and move.
I have reached the point where the cags I have are pretty much bomber and are as good as dry, even my Palm Shorty cag with only a neoprene neck is almost as dry as the other cags that I have in my gear bag. Other than the odd drip from the neck the cag is as good as water tight. The image above was taken after a bit of swimming practice in the Tees. Despite swimming and jumping into the water I remained pretty much dry from the waist up.
It is poisbsle that damage to the fabric of a cag or suit could allow water in. Small pin holes can be easily made by spikes plants or more common walking around in a dry suit without any shoes on, thus creating holes. It’s pretty easy to test gear for watertightness, find the holes and then carry out a DIY repair.
Another are where water can get in is through the seams. All good manufacturers tape all of dry gear to help keep the water out. This tape can be damaged, worn out or fail over time.
A number of the big players like Kokatat and Immersion research have very highly regarded customer support and can repair or even fully replace taping.
This gear tends to be pretty expensive so it’s a good idea to look after it and check over it for damaged once in a while.
You also need to consider that even the most breathable piece of gear will not be able to cope fully with high physical activity in a humid environment. I.E. fully cope with the amount of sweat produced by the wearer. If you are wet inside of your dry gear then it may not be due to a failure of the waterproofing properties of the product. It may need the Durable water repellency (DWR) sorting out to help prevent the fabric from wetting out and not able to perform as it should.
You will need to check with your gear’s manufacturer as to the best approach to renew the DWR coating. I have used both Nikwax and Grangers products with great success to reproof my gear.