Fiberglass degradation by salt water

[Charles123]

People always wash their fiberglass boats, the part above water obviously. I was thinking if there is really a need for it? What is suitable to degradation, the plastic matrix, or the fibers of glass? And how does salt water promotes that degradation?
Thank you
Regards

 

[Pkruse]

Fiberglass with common resins is hydroscopic so it absorbs water, hence the reason for coatings. They are washing and waxing the coating to make it look nice. If they did not do that, then the sun and air would degrade it and make it look ugly. But you can recover an ugly coating with a fine abrasive to remove the layer of oxidation.

You have similar but different concerns below the water line. They do that maintenance and repair once every year or two when they haul the boat out of the water and put new bottom paint on it.

 

[Charles123]

Thank you for your answer.
I should think that the effect of the sun is due to UV degradation of the plastic coating. Am I right? If so washing doesn`t help, isn't this the case?
As for the layer of oxidation, what oxides is the plastic coating, is that it? Wouldn’t it be possible to use some coating resistant to oxidation?
Regards

 

[Mike H]

There might be more than just UV degradation of the polymers at work here. If the water is getting absorbed, then the salt is certainly coming along for the ride. There could be concerns about salt buildups forming within the material that could be problematic. Washing with (presumably) fresh water could dissolve and flush out these salt deposits before they get to be an issue.

I don't know enough about this topic to say much else, except that oxidation is an ongoing battle. If you were to apply an oxidation-resistant coating one year, you'd almost inevitably have to do it again at some point afterwards. And again. And again.

 

[LudusRex]

I can provide some insight on the topic of fiberglass degradation by salt water. First of all, it is important to note that fiberglass is a composite material made up of plastic resin and glass fibers. Both of these components can be affected by salt water.

One of the main reasons for washing fiberglass boats, particularly the part above water, is to remove any salt residue. Salt water contains ions that can react with the plastic resin in fiberglass, causing it to break down and weaken over time. This can lead to cracks, discoloration, and other forms of degradation.

In terms of which component of fiberglass is more susceptible to degradation, it is difficult to say definitively. Both the plastic matrix and the glass fibers can be affected by salt water. The plastic resin can absorb water, which can weaken its structural integrity. On the other hand, the glass fibers can also be damaged by salt water, as it can cause them to break down and lose their strength.

The rate of degradation also depends on the concentration of salt in the water and the length of exposure. Higher concentrations and longer exposure times can accelerate the degradation process.

In conclusion, it is important to regularly wash fiberglass boats to remove salt residue and prevent degradation. Both the plastic matrix and glass fibers can be affected by salt water, so it is necessary to protect both components to maintain the integrity of the material.