i am planning to put a gangway out to the open water .it will run between to large bolders that are set deep. any suggestions on how to drill some holes in them and set some bolts in them.

Get a star bit and a big hammer.

http://www.answers.com/topic/star-drill-design-engineering?cat=technology

Then rotate the drill a bit and hit it agains. After a thousand hits you have your hole.

But they also make electric rotory hammers. You can rent them and the bit.

Also hammer drills, but they are slower light weight drills.

If this is "bascially" dry area then you can use one of the electric drills, but you will still want to make sure that it is protected with a GFCI.

If you have to stand in water then you need to cordless hammer drill.

You have a number of options for anchoring.

You can use an anchoring or machinery ground. It is mixed with water and expands to make to hold the stud. You can get it at a hardware store.

Or I like a Filled Epoxy. I have used Marine Tex to set eye-bolts which I used to attach some guy wires for a floating dock.

And there are several construction products used for anchoring. Get them at a HD or Lowes.

And there are various mechanical expanding anchors. Some have a stud that you put in the hole and tight up a nut. Others are a sleaved nut that ypu put in the hole and then insert a bolt.

Several types are available at hardware stores.

Get your anchor and determine the size of hole and the depth needed before drilling.