4-Post 20K Lift Wobble?
 

Lake Norman, NC (freshwater). Pilings are 30FT long, water depth is 12-15FT, and we have about 8FT of piling out of the water. I was told they drove pilings in ~5-7 FT. I am totally shocked because I can take my hand and easily make this lift sway back and forth 4-5 inches with an easy push? See You Tube video below. The lift installer built our dock, which is solid, and they are well known in area. They told me "with your water depth the pilings had to be so long that you are going to have some wobble, you can't avoid it." Still, is this normal and safe? We are planning to put a 35-39 Nortech with triple Merc's on the lift. Pics of lift and dock below along with video of the wobble.

You Tube

https://cimg9.ibsrv.net/gimg/www.off...914267619.jpeg

wow that is gorgeous. I'd love to build something like that someday. government wont even let you put a car port over boats in MD. Apparently the light doesn't get to the disgusting water below.

what are the pilings made of ? can you do some cross bracing below the water line,

Yikes!

:eekdrop:

Can you tie all four corners together at the top? ... and X-brace the frame at the top also. Maybe also tie the lift to the dock structure. That is way too much wobble.

I Am a little shocked that it looks like 4 x 4 pilings. Around here a lift that size would be on 12"-14" round pilings.

I wouldn't put a boat, not even a Sea Doo on that. On a windy day loaded imagine what is going to go on.

the pilings appear to be the same size as the dock structure ? 10 or so inches

I would expect to see some X-bracing side to side. And I would expect to see some longitudinal bracing down lower to create a boxed infrastructure.
Once that is done, you could tie it into the dock structure.

I'd take a ride around a look for other similar boat sizes to see how their lifts are fortified.