Kevlar degradation

[FuzzyBadger]

Is there a way to tell the condition of the Kevlar on an old (1979) Wenonah? I'm referring specifically to UV damage.
Overall, there are not a lot of scratches or dings. But, I wonder if the Kevlar has become too brittle to bother restoring.

 

[frozentripper]

If the kevlar was shielded from UV by a layer of paint or gelcoat or some other kind of protective coating, there shouldn't be damage... OTOH if the kevlar fibers are visible, maybe. UV will also break down the resin that the kevlar is embedded in maybe resulting in weak spots or delamination.

Canoes that have been stored outside in sunlight and unmaintained for long periods can get brittle and they will crack or break open if there's some stress on the hull. I have a fiberglass canoe made about 1970, always protected from UV with paint and garage or basement storage and the resin is still holding it together well enough to withstand some hard knocks.

Pressing down hard with the heel of your hand on various parts of the hull might be useful... hearing ominous cracking noises is not good and neither are soft spots that have gone mushy, that aren't firm and resilient like the hull would be in new condition. You want a hull that will be able to take the range of stresses that it will subjected to in normal use, so test it to whatever level of stress you feel is necessary to show that it's still capable of standing up the wear and tear that's going to happen when it's being used.

 

[yellowcanoe]

Its tough to tell. I have a 1991 Wenonah that would flunk FT's test. Aside from the winter it spent under five feet of snow it has always been inside. All of the sidewall is soft and mushy. It has always been that way
Why? Because two layers of Kevlar are not stiff without something else in there. It was made that wayThe bottom and ends are of course stiff as there is glass and a stiffening core.. Be familiar with the construction of the canoe and be aware. Sometimes flex is fine.

The chief problem is cracks in the skin coat or gel coat that expose fabric. Kevlar is hydrophilic and when wet loses some of its strength. Surface scratches no big deal.

Others of my boats have soft areas as canoes are made with multiple layers of fabric and all them are not of the same shape. DragonFly has 38 pieces of fabric.. some partial some full. It has some softer areas where stress is not as significant.

 

[FuzzyBadger]

Thanks guys. I'll give it your test frozentripper.