Re: 4 1/2 diameter hole 36" deep for my dock
 

I lieu of drilling a hole in one, can you 'V' notch the sides of three and wrap each steel pipe? Then you can wrap the whole thing on the rope. Kinda like this - I did on my sons bed.

Re: 4 1/2 diameter hole 36" deep for my dock
 

And most poles are not straight . I would think they would split also.. Do the PVC and paint some stuff on them . Make em into fake palm trees?

Re: 4 1/2 diameter hole 36" deep for my dock
 

Find a buddy with serious wood working tools and a desire to try something unusual. He'll need a band saw with 12" resawing ability minimum, and the infeed and outfeed tables to support a log the size you are wanting.

Rip the log 2.5 inches from centerline on each side, leaving you a 5" wide slab from the middle. Now rip up 36" from the bottom on the flat side of the slab, again 2.5 inches from the centerline. Bore holes large enough at the ends of those rips to insert a sawzall blade in. Use sawzall to crosscut between the holes. This will remove a 5" x 5" x 36" section from the middle slab. Now re-glue the log together (leaving out the 5x5x36 section)using polyurethane glue, or another waterproof glue that bonds well to green wood. Epoxy may work here too, I'm not sure with the green wood though.

Finally, make sure the tops of the log is not flat, or water will wick in and rot it out. Best to actually cover it with a cone, or at least cut it on a slant.

Re: 4 1/2 diameter hole 36" deep for my dock
 

If you really want too, look into log home or timber companies they may already have the drill bits to do the job, or you could buy the bits and have any machine shop with a boring mill do it for you, these pictures are of a 6" dia wood boring bit.

Re: 4 1/2 diameter hole 36" deep for my dock
 

get a woodworkign shop with a large lathe they shodu eb able to do it. I thin it will split though.