Gord- you are right to say that its a job only for somone who knows what they are doing..
Shoud have said my brother in-law is a very experienced shipwright who works as a senior marine commercial
for a Govt agency and got his instructions from a mate who is a Lloyds engineering surveyor
who is also in the lifting gear
& chain supply game!!!
Best left to the pros - but can be done....
What is irritating is that they make this sort of stuff look so easy - that sometimes I think oh yeah no problem I can do that too or that anyone could do it as well....