In article fg2Of.326$wp.67@fed1read12, Steve B
wrote:

"rigger" wrote

WHOLE BUNCHA STUFF SNIPPED

I have worked in the trades. I was a commercial diver. I was a certified
crane operator on drilling platforms in the Gulf of Mexico. I worked
assembling and disassembling derricks. I was a steel erection contractor in
the State of Nevada for nine years.

All required rigging knowledge.

I was certified by Offshore Petroleum Institute, the regulatory agency at
that time. I have attended many inhouse training programs and union held
classes on rigging that were recognized and sanctioned by OSHA.

I do know one or two things:

I have enough experience to know that if you try to lift things with rafter
trusses, it will work, or if will fail.

I know that if you ask a structural engineer if it will work, they will
simply tell you it is a bad idea.

Actually, that's not true, and I have a structural certificate from a
practising engineer to show for my asking. Told him I wanted to lift a
max of 500kg from the centre point of a 7.2m span truss and he told me
what size truss I needed to order from the manufacturer.

He also said that up to 200kg, don't worry about it. That's the SWL
anyway. NB, I said SWL, not max load before failure.

YMMV if you have poor engineering standards where you live.

PDW