Originally posted by GunsForBucks:

You can place a wooden beam normal or log sticking out half way.
That way you can walk out "in front" of the extended part to place new ones, once you have one in place you can snap the row to the side of the first one.

Yeah, Also We meat again. Another thing you could do. is Build a cart and just roll it into teh water. Still allows you to build and even walk to where you want to go in the water