O.K. Menards finally got in my underground rated 4x6's so I can build the "on-land" portion of my floating dock, then continue with the gangplank, then the floating portion of the dock.

With the wonderful winter that we had, I could not build the floating portion on top of the ice, so I have to build it on shore and drag it into the water. I plan on putting the barrels on top of PVC pipe that is laying on the ground, so the dragging part is a little bit easier (plastic on plactic).

But, for the guys that have built a floating dock before, what do you use to keep the barrels under the pier, if anything?

The floating portion will be in the shape of a "T", with the top of the "T" 12' wide by 8' tall, and the bottom of the "T" 4' wide by 16' long. I'm building it big enough so that it won't lift out of the water if a number of people stand on one corner, but the opposite of that is a barrel, if popped out, will be a royal PITA to put back under.....

The joists will be 2x10's, and the plan is to have 50% of the barrels in the water - keeping the wood close to but not in the water.

Dang, I didn't realize how expensive Stainless Steel screws are now! Deck will be 1x6's. I was going to go with 2x6's, but I got a deal on the decking and the 2x10's that I just couldn't pass up.

Mine are framed in place at the top, then stainless cable ran underneath te hold them in place.. You might not wanna put the deck on til it's on the water.. Put it this way mine was not easy to get from bank to water and I had a little drop off before the water so my barrels were every which way so I had to take some top boards off to reoganize my barrels, haven't had any trouble since..

My FIL has a floating dock made with plastic barrels and wood like this. They take it out and dismantle it every winter and I helped to put it together last spring so I saw how it was done.

Here is how his works.

First put eye hooks on under side of the main support beams such that you will have 2 on each side of every barrel. Second you run the barrels parallel with the main support beams under the decking that way the weight of the dock its self helps to keep them in place in between the 2x10 (or whatever you used) beams. Third take 2 bungee straps per barrel and strap them into the eye hooks. and around the barrel.

The straps combined with the weight of the dock and the friction of the joists should keep the barrels in place nicely.

You'd think the weight of the dock would keep the barrels in place under the dock, but during a storm, I had one come out. I originally straped them in place with galvanized band, but it quickly rusted right thru. I'm not sure how bungee cords would hold up under water continuously, but at least they wouldn't rust! I would think long rubber straps or even a small diameter stainless steel cable would be sufficient.

I'm having trouble visualizing how to tension the stainless cable against the barrels but I agree that the stainless steel cable sounds like a winner for durability. I don't know about the life span of the bungee straps for 24/7/365 use because my FIL's dock is a seasonal swimming dock but I can ask him about the life span of his bungees under seasonal use conditions the next time I talk to him for you.

Sunlight eats bungee cords up in just a few months. They crack and break in 2 months.

You really don't need much tension on the barrels. Just enough to keep the barrels in place.

One way to hold cables would be to use lead cable claps you slid over the cable and crimp with vice grips. I've used them on my sailboat stays that can be under a lot of pressure. You could run the cable through the eye bolt/screw, then a washer with a hole smaller then the lead crimp. On the sailboat cable stays I used two at each end for double safety.

I used cable tensioners.. Atleast that's what i call them.. Basically it's a device you solid mount on one end then attach the cable to the other end.. Then twist the inner part of it and it tightens down the 2 eyeholes on each end..

Not sure if this link will work but it's called a turnbuckle after a little research I found my half this price at local store

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Nickel Plated Cable Turnbuckle for Cable Display System

If ilink don't work just check eBay lol

Yep, turnbuckles would work long term, along with stainless cable. I'll sketch out the dock plan on something that I can upload to the forum tonight. Right now it's done with pen and paper......

I actually used aluminum turnbuckles with stainless plastic encased cable. Eventually I plan to solid mount my dock until then I'm sure it'll hold.. (just waiting for a trackhoe to magically appear and beat in 6x6 post for me lol)

I did just as DMRBG did but used 1/4" nylon rope. Place a screw in eye bolt near each end of the barrel (4 total) and tie one end of the rope to an eye bolt.
Next thread the rope through the additional bolts in a criss-cross pattern and tie a loop into the rope about 12 inches from the last eye bolt. Now thread the rope through the loop and back to the last eye bolt and tie it off. The loop will just add leverage when you pull to tighten the rope. I did this by myself and it worked well but would have been easier to get more tension with an extra set of hands.
I'm not the best at explaining things so not sure if this helped or not. A picture speaks a thousand words.