Rock anchor for dock lift

[SkunkedAgain]

I've got a lift-out dock. I've been running a strap around a relatively stout birch when I lift the dock up. However, there isn't a lot of soil (think BWCA area) where I'm at and don't want to come and find the tree tipped over some day and the dock back in the water. If done a few internet searches but can't seem to find anyone that sells a bolt or anchor that is suitable for drilling into a giant rock and using as an anchor point. Does anyone know where I can get such a thing?

[delcecchi]

I went to amazon and typed in Anchor Bolts and found several options.

Something like this maybe to bolt a steel plate with eye to the rock? 

http://www.amazon.com/Vestil-AS-383-4PK-Concrete-Anchor-Diameter/dp/B00AAME8W4/ref=sr_1_2?s=industrial&ie=UTF8&qid=1443560637&sr=1-2&keywords=anchor+bolts

This type of bolt comes in a variety of lengths and diameters. 

L&M Fleet Supply, or some sort of industrial construction place in someplace like Virginia is where I would start if I didn't see anything on amazon. 

How about the lead anchors? Like are used with lag screws.  

Another choice would be drill an oversize hole, fill it with some sort of concrete and stick an eyebolt with a nut on in into the wet concrete. 

(looks like the outfit selling these on amazon is our good friend from Minnesota, Northern Tool and equipment. )  Their page might be worth a look. 

[DANR]

The Quickbolts pictured hold very well, but the hole has to be drilled pretty precise,which might be tricky in hard rock.

 

[BoxMN]

I also have a lift dock and using an oak tree.

But on the pivot end of the dock, I have a huge boulder that the installer drilled into and fabricated a steel plate to help secure the steel "hinge" to the shore. They used three of the bolts pictured above to mount the plate to the boulder. The drilling actually went pretty quick and they said it was solid as a rock  

Good luck! BTW I love my dock, 32' long with a 12x8 end, and it takes me less than 5 minutes in, 5 minutes out, without my feet even needing to think about wearing boots of any sort  

 

edit, here is a pic of mine that I found - can still see the drill dust even:

Edited September 30, 2015 by BoxMN