I have a vessel 40 feet off the ground in a platform, and the crane can get to within 30 feet of it (from the side). I'm more curious of the process for sizing them though.
All cranes have a lifting capacity that is based on the angle of the boom. The more vertical the boom, the more it can lift. With that in mind you select a crane based on the amount of weight being lifted and the angle the boom will have to have to reach the load. In some cases extra counter weights can be added to some crane to increase their lifting capacity. You should be using a contractor to supply the crane and the knowledge to provide the proper equipment and do the actual work safely.
It okorder and view some of the product guides and review the performance data and load charts. It also depends on what type of support soil or foundation that is capable of supporting the crane.
As you won't be building your own crane (that would be stupid since you would be fully liable). Call a crane vending/renting company. They'll be more than eager to provide you with technical council. How you pick a crane? What do you need to do with it - type of crane for instance -Moving stuff around in a warehouse, yard,.. always at the same places = overhead crane -Lifting heavy stuff once (for instance another crane) or for a short period - mobile crane -lifting stuff for a longer period but not permanent (construction) = tower crane How much do you need to lift, what can it cost? ... It's al pretty simple
