Threaded rod under pier

[Thomas_Blekinge]

Here's a simple sketch

Well, it's a stone chest. That's not what the TS wants to build.
To TS: Read the book "Bryggan" by Claes Dymling. Very worth reading.

 

[Rattan]

It's a stone pier. That's not what the OP wants to build.
To the OP: Read the book "Bryggan" by Claes Dymling. Very worth reading.

no, that's correct. The bridge is where it is, the stone pier has been in place for a long time. I'm just going to reinforce the structure, all well above the waterline.