What do they call those jack stands for lifting a boat off a trailer. They are typically about 4 feet tall and have wheels and an extended pair of arms that stick out to reach under the edge of the hull so you can jack the boat up off the trailer. They are usually hydraulic jacks. Don't know of any ratchet types.

Who are the manufacturers of these?

Any ideas on building some?

I have thought of adapting an air powered bumper lift for cars. They have a pair of arms that stick out fairly far.

Here's a link
http://www.yardarm.com/
Thought I had some other links but can't find them.
Hope this helps,

Caleb

Thanks for the link. That is what I was looking for.
If you have others you can scratch up for me, I would appreciate it.