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.