If you've woken up with moisture on the inside of your bivvy, you could be forgiven for thinking it has leaked through the night, however, the more likely cause is condensation. Condensation occurs in all bivvies and the amount of condensation can vary due to several factors.
Is my bivvy leaking or is it condensation?
It is highly unlikely your bivvy will be leaking as Cyprinus bivvies are made using the latest, highly-waterproof fabrics with strong seams, which are then carefully tape sealed to keep the worst of the weather out. The reason for water inside your bivvy will usually be due to condensation.
Why does my bivvy condensate?
Condensation is caused by warm air on the inside of the bivvy hitting the relatively cool bivvy fabric, causing it to turn to moisture. Condensation can show in various forms, from droplets inside the bivvy to patches generally around the head end, or in some cases all over.
What makes condensation worse?
Heavy rainfall can increase condensation, often misleading people to thinking their bivvy is leaking. This is because rainwater on the outside of a tent or rainwater evaporating from fabric rapidly cools the fabric and causes condensation as the warm air inside hit its.
After very heavy rain I can see some dimples inside my bivvy. Is this a problem?
The coating applied to the inner of the base fabric is designed to minimise condensation. Small dimples may form on the inside of the shelter as the inner coating absorbs moisture and repels it through the outer fabric. This will be more apparent during periods of heavy rain or humid conditions when condensation build up would normally be at a high level.
This is a temporary physical effect and when dried out this bubbling effect will disappear.
How do I minimise condensation inside my bivvy during use?
Use a wrap, skull cap or inner capsule where possible.
These bivvy accessories are designed to create an air cavity between the inner and outer fabrics which reduces condensation significantly. They still may not eliminate it completely in the most severe of conditions however, in the majority of situations they help enormously.
Increase ventilation. A single person can produce more than one litre of perspiration in a night, so an effective way of reducing condensation is by leaving your door and/or vents open (weather permitting).
Use a ground sheet. A huge amount of moisture comes up through the ground, therefore using a groundsheet prevents it from entering your bivvy.
Never cook or use heaters inside your bivvy. The key point here is safety. It is extremely dangerous to use heating devices inside your bivvy. Cooking releases large amounts of moisture in to your bivvy, that’s why we use extractor fans in our kitchens at home, therefore always cook outside of your bivvy. In cold conditions, rather than heating your bivvy, we recommend using the right clothing and sleeping bags.
Keep off the bivvy fabric. It is sometimes hard to avoid, but your bed, chairs, bags or other items should not be touching bivvy fabric, as this can increase the effects of condensation.
Store wet items outside: You should not be drying damp stuff inside your bivvy, such as clothing, towels, boots etc. as this can make the effects of condensation much more severe.
Avoid being too sheltered. A natural breeze can help with ventilation, whereas an area which is too sheltered can promote condensation.
Have a dry towel available. If the conditions are very severe, particularly in humid conditions where you have followed the guidelines and you are still getting a condensation build up, simply use a dry, clean towel to wipe the condensation away.