Reversing Fibreglass Osmosis

Do you want to find out how we reversed the moisture build up in our fibre glass boat hull for less than £100 ?

The biggest unknown in our rebuild project was our ability to ward off future osmosis stemming from the excess water which had seeped into the core of the hull over the years. The advice we had been given was that if it was not showing now and if we resealed the bottom of the boat with Epoxy that there was a good chance that it would not become a problem. While we trusted the expert opinion that we would be OK we decided to give some drying options a go.

What is fibreglass Osmosis ?

The gel coat finish on the exterior of many fibreglass boats is reinforced plastic which is porous. As water is a solvent, when boat is afloat the water reacts with the fibreglass to create a weak solvent solution, usually with styrene. The process starts from the day the boat is launched, gradually increasing the longer the boat is in the water.

In the worst cases this reaction will soften the gel coat, over time the build up can combine with gas or fluid pressure which results in the external water getting sucked into the small pockets of space within the laminate. Filling the gaps in the fibre glass with water and soluble components left over from the build process.

In the most extreme cases this buildup can present as an external blister on the surface of the boat. In simple terms if you leave your boat in the water for extended periods of time the chemical reaction can slowly suck moisture into the fibre glass and further into and reinforcement inside the hulls core (usually closed cell foam or wood). If enough water is sucked in the chemical reaction can produce enough pressure to create external blisters in your boats finish.

Learn more about the process and follow our Mumm 36 rebuild at.

https://bupboats.blogspot.co.uk/2017/...