Boat cradle design

[Littleship]

Probably a simple matter but one I just cant grasp on how to safely support the boat while its worked on. The boat in question is a coronet seafarer 27, 8.22m length, 3.16m beam with a .91m draft with a 4000kg displacement. I would like to build a cradle for the boat to sit in while it has work done which will safely support it while allowing people in and on it. Something similar to this http://www.boatshop24.com/web/en/wer...=1&lastshow=75 I'm unsure what points of the hull are best to run supports onto and over what length the stand should run. Any thoughts or other idea's would be helpful.

[War Whoop]

You Can not just support the keel and use yard jacks/jack stands to stabilize it?