Modern synthetic mountaineering ropes can take up more than 35% water in practical usage. This increase of weight affects their handling properties negatively. Furthermore, a wet rope runs the risk of icing. Moisture, on the other hand, affects also the dynamic behaviour of mountaineering ropes. The investigation of the water repellent effect of such ropes, however, is currently based on static test methods, which are unrealistic compared to practical usage. A new method for the moistening of mountaineering ropes, called Rope Working Simulator (RWS), has been developed that allows the moistening of mountaineering ropes in a more practical way than other methods do. With this equipment, the rope is sprayed with water, moved and bent around artificial carabiners to simulate effects of practical usage. After the treatment in the RWS, the ropes were tested dynamically according to EN 892 in order to quantitatively investigate their behaviour in the moist state. For a rope humidity greater than about 4%, the number of drops sustained decreases significantly and for a humidity greater than about 25%, the number of drops sustained can fall below the threshold value given by the standard (5 drops). This decrease is accompanied by an increase of the impact force, which can reach up to 12% for fully wet ropes.