dock questions

if you look at my profile pic, you can see my dock.

I want to make it such that a boat can tie up to either side. The problem is that the water level fluctuates enough that a boat can slide under the dock. Im looking for ideas how I can extend that 2x12 down so I can attach some tires ore bumpers.

any ideas? im thinking of having a welder come out and weld some brackets to the poles, but with the water right there, it doesnt seem too safe to me

You could put vertical uprights lagbolted to the dock about 10' or so apart. However, I would wait until the water does fluctuate, and then I would run another board horizontally and bolt it to the poles. The just run that dock edging stuff down both rails, top and bottom.

I have done the same thing to my dock. The easiest thing is to drive vertical pieces of heavy duty PVC down into the lake bottom, and cut off even with the deck. I lag bolted them so the bolt head is recessed. About 18" or 24" spacing works. Use 1.5" Schedule 40 PVC.

a picture says it so much easier. This is actually inside the slip to keep the bow from getting under the edge. Notice how the top of the pipe is cut at an angle to recess the lag bolt.

I hate going to someone's dock where you can't tie up in a way to protect your boat. No way to relax when you're watchin' out for rollers.

thanks for the ideas guys, thats exatly what I want to do.