The microstructures, water absorption as well as blistering was studied for bi- and tri- axial glass fibre vinyl ester and polyester -matrix laminates coated with gel coat layer and uncoated. The effect of manufacturing technique on water sorption characteristics was considered. It was found that water sorption characteristics of GFRP depend on manufacturing methods. The least water intake was found for specimens having perfect microstructure due to manufacturing by infusion process. Water sorption saturation value was reached after ca. 50 days of accelerated test at 70°C and was found to correspond to 250 days conditioning at 20°C. Blistering evolution was illustrated and SEM images shown corresponding to degradation of the gel coat layer and the laminate during the exposure in water.