Osmosis is one of the most costly and major problems for a boat, which manifests itself as moisture and water bubbles in the hull coating of GRP (Glass fiber Reinforced Plastic) boats, with its simple definition. Since it is an invisible problem in the early stages, it should be examined by a professional person or team using devices designed for osmosis measurement. An area with osmosis that cannot be noticed before purchasing can lead to a very long and costly process afterward, resulting in both time and money losses. The Osmosis survey, which will be carried out every 2-3 years for GRP boats, can detect the osmosis that may develop unnoticed on the boat early and can be eliminated by prevention and repair operations in small areas before it spreads.