I was using the frame of the dock for locating the posts initially I tried the red 0 degree nozzle but lost it after the quick connect unlocked while moving it up/down under a post. Turned out the yellow 15 degree nozzle worked better. I set the post upright used a piece of string to tie it off to the frame plumbed. Just worked the jet around the post in the perpendicular plane then slowly undermine the bottom material. I made use of a fire brick block that was laying in some old materials dumped for seawall erosion. Set it on top because the posts wanted to float after going down a couple feet. I grabbed a bunch of bags of pea stone from the local Ace and poured them around the posts and over time the mud and sediment should lock them in.
I know this thread is a bit old, but I came across it and wanted to ask how the 5x40 finger dock turned out after the setback hassle Did you ever get the bracing figured out for the posts once they were sunk with the water jet? I’m planning something similar and curious if square posts held up better than round ones would have
I'd go with square posts for easier bracing Build the main frame first, then attach the walkway, and brace diagonally at the corners
For bracing, I used diagonal 2x6s between posts and kept the frame level before adding decking Since you have a long finger dock, wave action can really work the joints loose over time A good anchor rode from American Rope has helped me secure my own floating setup during storms and that same durability applies to any mooring line you might add Your 5x40 design sounds practical, just double-check the walkway connection
MoiseiWEwe Another avid boater I see. Our season is done for the year, I put my busy away in storage last Thursday night.