OSMOSIS IS A TERM THAT STRIKES FEAR IN THE AVERAGE BOAT OWNER, BUT THAT IS NOT NECESSARILY THE CORRECT REACTION.
A boat is not in jeopardy because there are a few patches of osmosis. Left untreated it could, eventually, become a serious problem. Remember, no boat has ever sunk as a direct result of this problem, but large areas can weaken the hull structure eventually.
Osmosis is something that is often easily fixed with a little hard work.
Osmosis is synonymous with GRP (“Glass-Reinforced Plastic) boats only. Typically found in older boats for several reasons. Not least that earlier construction methods with this ‘new’ material at the time may have had more manufacturing faults and also because older boats have spent longer in the water. However, modern boats are not immune.
A BOAT HULL IS OFTEN A MIX OF POLYESTER RESIN REINFORCED WITH FIBREGLASS – AND COMBINED INTO LAYERS TO FORM A LAMINATE – THIS IS THE GRP.
This laminate may have tiny voids (air pockets) between the fibreglass and the resin. A thin layer of gel coat that resists the effects of UV exposure and provides a waterproof barrier is then applied.
Osmosis is the process of water diffusing through the gel coat and into the laminate, which then condenses into any voids in the GRP material. Osmosis blisters are easily identifiable and even running your hand along the hull; you can feel whether or not you need to act.
Blisters form when the water inside these voids reacts with the laminate, and they get bigger as this reaction develops with pressure. The process is known as Hydrolysis – a chemical process of decomposition involving the splitting of a bond and the addition of the hydrogen cation and the hydroxide anion of water.
This process is not reversible by merely taking the boat out of the water for some time. Osmosis (blisters) ultimately need treatment.
SO, WHAT IS THE SOLUTION?
Depending on the gravity of the affected area, several treatment methods are available. Small localised blisters are usually ground down to the laminate to evacuate the trapped water. You know it is osmosis when you smell vinegar as the water is released. Once evacuated, the blisters are washed to remove any remaining chemicals and left to dry.
A Moisture Meter provides a picture as to dryness and therefore the overall integrity of the hull.
Once an acceptable moisture reading is achieved, these isolated blisters are filled with epoxy resin. And, because this all takes place under the waterline, you do not need to apply a gelcoat over the new resin. The resin itself is waterproof.
LATCHI MARINE SERVICES CAN TREAT EVEN THE WORST OSMOSIS, AND WHILE TIME-CONSUMING, A NEW LEASE OF LIFE AND VALUE IS RESTORED TO YOUR BOAT.