Lifetime is running out for a large number of fibreglass boats produced about 50 years ago. Many shipyards where they have been produced do no longer exist and last users frequently do not have the budget to pay expensive disposal of their boats. After having been chopped and shredded the only further (but still expensive) use of the fibreglass seems to be as a waste component in concrete or asphalt.

Is there really no better use for it, where it even may be considered as a value? If not, we are running a high risk that many boats and other fibreglass products in future will end up in the sea as an additional waste load.

GE reports about some recycling of wind turbine blades, which may be true or just to reassure some critics. However, I fear that there will come a lot of none recycled fibreglass waste to nature.

As building riffs with waste fibreglass materials was suggested as an alternative I would like to point on this study which states in its conclusion: "Evidence of matrix and interphase contribution in environmental degradation is shown by crack density measurements, transverse strength degradation, and fiber surface morphology."

Even when it decomposes slowly and takes some hundred years to do, that doesn't make it better for the ambient.

  • Just a thought: Is a (de-oiled) pile of boats on the seabed, in a well considered location all bad? Artificial reefs have their merits I understand. Might be less environmentally damaging than the energy used to reprocess. May 8, 2018 at 7:29
  • That proposal could also contribute as an answer to a previous question about "How do plastic bags and other waste end up in the ocean?" Even when fibreglass plastics do not rot fast, small parts of it can remove from the body of the boats and drift in the sea. Building riffs may be better using steal, as it is in cars, etc.
    – Salt
    May 8, 2018 at 13:00
  • Fibreglass is pretty inert. I've not read anything on the effects of ultra long-term immersion in sea water, but bits don't spontaneously break off boats. If they became colonised, the encrustations, concretions and other growth layers would protect the fibreglass to a not inconsiderable extent. May 8, 2018 at 13:29
  • Most boats are protected against osmosis from outside, but not from inside the boat. Osmosis will start very soon where water penetrates the material and creates growing bubbles that finally break up. Fishes and other animals will nibble and eat it. So it enters into the circle. And as it is inert indeed you will find it some day on your table.
    – Salt
    May 8, 2018 at 13:47
  • 1
    This item was also discussed at other place in StackExchange: outdoors.stackexchange.com/questions/14206/…
    – Salt
    May 8, 2018 at 14:09

2 Answers 2


Realistically,the problem could be solved taxes to encourage recycling of the boats. Otherwise, the waste product is too invaluable and the recycling process too expensive to be used commercially.

The problem is that virgin fiberglass and epoxy are relatively cheap, while being challenging to recycle due to the strength and size of the fibers and the epoxy being a thermoset.

Use of the fibers as a reinforcement in concrete provides real benefit if taxes support the additional cost, and is a likely application. The fiberglass has also been crushed to be a base component of concrete.
Breakthrough: Recycling of fibreglass is now a reality

The fibers have also been used as reinforcement for new thermoplastic materials, but the process is proprietary and doesn't seem to have much traction in the industry at the time of writing.
Perhaps we’re getting closer to fiberglass recycling

You might be interested in the pilot study in Rhode Island on the subject: Can Boats Be Recycled?


Fiberglass boats have a weight advantage such that they are not going to lose popularity. Most likely old boats will go to a landfill.

However, steel boats have gained popularity with home boat-builders because local shops with $15000 in equipment can cut steel plate on shop floors using computer files.

Now consider replacing all steel usage with stainless-steel. The stainless-steel will not rust or corrode and therefor will be most valuable in recycling. The low-cost 409 SS is currently alloyed for welding but not found in very many structural shapes. More likely simple shapes are bent from 409 sheet-metal. The more expensive 304L is designed for welding and is available in all structural shapes. Of course 304L has a significant nickel content and that's the expensive aspect.

Buy the stainless-steel wholesale, in twenty foot lengths, and by the truckload, and it's not too expensive. Or buy stainless-steel sheet-metal on coils and by weight. Then stainless-steel cut off the coil can be directly attached to supporting spars but must be flattened if it is being bent to shapes.

A freshwater boat can just be built from stainless-steel. A salt-water boat built from stainless-steel still needs painting but the stainless-steel needs a heavy-brushed finish to hold paint. A standard #4 brushed finish might not be enough of a brushed finish. There are pebble finish stainless-steels for roofing and those might hold paint.

Roofing ? 430 is good for roofing because of lower thermal expansion but 444 is similar while almost as good as 304 for corrosion resistance. Don't touch 409 or 430 with a cut-off disk but cut them with machine tools.

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