Kjell, how big of a crane would somebody need to swing 10-20K pound boats from a trailer into the water if you could get pretty close like your set-up above? I am thinking 40-50 ton? Also, the crane would be able to stay in one spot, so is an old crawler the cheapest way to go?

In situations like this the knucklebooms are great.

Yes i Think an old crawler is the cheapest way to go. if you will hawe it stationed there for some time, 20000 lbs is 9 tons. So a 50 t crane vould probably handle about 20 t at least.

This old macine where in use on a Construction site in Stockholm about a year ago.
It was wery exhiting for me to Watch it..i hawe newer seen such a pice in work Before.

But i can also hanle a bucket :-).