: Then , other than increase the thickness, there is no reason to use
: it ?
: Then , how can the canoe / kayak coated with epoxy finish avoid
: from UV light damage ?

Hi,
UV protection comes from coating with a varnish that has UV protection properties, (exterior varnishes) or paint.
Some epoxys have an added UV protection but it only slows down the degradation rate, it would still need varnish or paint for full protection.

Mike Savage
South West Cork