Oh...the highest work comp rates(at least in LA) are pulpwood loggers. Underwater welders are almost always covered under Maritime laws, very few fall under comp laws.
I don't doubt you, I am sure that the worker's comp will be avoided whenever possible. On the other hand, what happens when they can't ? I was unsuccessful at finding a directory of worker's comp rates for various fields.
I think pulpwood logging would largely work out the same as any other kind of logging: HIGH ! Around here, there is no logging, so tree service is close to the top. A contractor I work for occasionally told me his rates for demolition are about 100% of payroll whenever his men work above the first floor. I don't know how the insurance company would audit that, but he did admit that most of his demolition got knocked down by the excavator to less than two floors.