Building a dock

Thinking about building a floating dock on a pond. I have access to an old 30 foot mobile home. Thinking about using the frame, floating it with barrels, and adding decking. People use treated wood all the time just fine, but I dont know how the frame weight compares to treated wood. Anyone done this?

Barrels will work but not for long. They will rust out in less then 5 years guess how I know. Back in the early 90s I worked at a dock building company and build hundreds of dock frames. The mobile home frame will work but you need better flotation

I live on a lake, and a big tree fell on my old cedar deck after a storm.
It had styrofoam blocks for floats. The styrofoam floats are no longer legal - can't be re-used.

I built a new deck using commercial (blow-mold) manufactured floats.
It's a lot like building a hayrack only with 2x8 and 2x10 lumber.
Most of the neighbors have a deck like mine but a few have bought commercial steel-frame decks.
The commercial steel frame decks use galvanized steel for the frame and have legs going down into the lake bed. No floaters.
I suspect your mobile home frame will rust out more quickly than your steel barrels.

A couple of neighbors have used the heavy plastic food-grade barrels for floaters on a treated pine frame.
They seem to hold up well.

I used composite decking for the surface on top of a treated pine frame.
A neighbor built a deck similar to mine only using treated pine decking.
They are both eight years old this summer and both holding up well.

The manufactured floats can go flat or suffer other damage.
I currently have one that has lost its ability to hold up its corner of the dock.

Which lake in MO. I'm at the Lake of the Ozarks and worked for a place called Gal-A-Foam back in the 90s and build a lot of docks here at the lake and also for all over the world

I built one similar to what you are looking at, angle iron frame, blue plastic barrels for the floats, lock-tite the barrel caps and silicone around the outside of the caps. I happened to get some plastic
5/4 horse fence boards at a consignment sale, the boards were paintable and pretty stout though I did end up putting probably a third more runners under the boards than I would of had to do for 2'' treated
lumber. Has held up well for over 6 years now, I did go back and re-paint the boards with non-skid added to the paint, running grandbabies.

Unless the water level rises and falls a lot, a fixed dock will be simpler and cheaper to build. If you have a trash pump or other high-volume water source, you can shoot pilings into the muck with a pipe plumbed to the pump. As I recall, the pipe is around 1-1/2 inch diameter and pinched at the end. Set the piling where you want it, then push the pipe into the muck next to it and the piling will sink right down.

When I was a kid my father built a floating addition onto a fixed dock. He would pull it out in the fall before freeze-up. I know that even though you don't specify plastic drums that they are what you intend to use since they are so readily available. The mobile home frame would give you a lot of space. You would need drums on only the outer half.

You want weight on it to stabilize it.

Need to do your math, determine the flotation ability of the barrels (plastic I assume), shoot for about 1/2 submersion.

The favorite decking around here is galvanized 2x2 angle, galvanized corrugated steel laid in the frame, poured with concrete. There is a product called Cool Creete or something like that, stays much cooler than regular concrete or even wood.

This is a once and done method, will last for a long time, no splinters, no weathering, no damage from rising water, especially on a fixed dock.

As far as the frame is concerned if its properly coated to prevent rust I don't see a problem using it, and as far as the
flotation devices are concerned Id prefer plastic or some have used old aluminum pontoon boat floats. Those are ONLY options
Im sure you will come up with a method that suits YOUR needs and is within YOUR budget.

Good luck with it and best wishes

John T God Bless America keep her free from socialism

One of the nicest floating docks I have ever seen was concrete, at the city park in Starbuck MN!

Don't use white plastic barrels, they are not sunlight resistant and will fall apart in a few years.

While a dock is constructed from the bottom up the plans are drawn from the top down.
You need to know the weight of the top to be able to figure the flotation needed for the bottom.
To much flotation and not enough weight and it becomes tipsy.
Not enough flotation and to much weight and it sinks.
Weight of the dock will be equal to water displaced.
By knowing water displaced you can now figure total flotation.
The common practice around here is to use blue plastic drums.
They are much stronger and thicker than molded dock pontoons.
They also do not rust like metal drums.
You want the drums to be half submerged.
This gives you some stability.
Also the bigger the dock the better.
People weight becomes a smaller percentage on a large dock.

A friend of mine has a prefabbed dock made out of aluminum and blue drums.
More like a barge than a dock.
Has a axle and wheels under it and a motor transom.
Has a one room house built on it.
Fully licensed as a trailer and boat.
He pulls it down the road to the boat launch.
Put it in the water and move it to his leased land.
Goes about 2 or 3 mph.
Once on site they use it as a fishing and hunting camp.
When finished he pulls it home.
His hunting and fishing lease is so remote people would break in and rob a built on site camp.

Lake Champetra. Southern Boone County.
50-some homes and a cranky HOA.

In theory, displace 1# or water it will
float 1# off steel.
Displace 1 gallon of water and it will
float about 8.6 pounds
So if half a 55 gallon tank is sunk below
water then do the math. Half of 55 x 8.6
pounds
Do your math before you build to
determine how much water you need to
displace.
That simple

Couldn't resist the math problem. 55 gallon X 8.6 is 473 divided by 2 is 236 pounds of displacement per barrel at half way. 6 barrels is 1,416 pounds of displacement.

30' trailer with maybe 6" C channel frame. 60' of 6" C channel at 8.2 pounds per foot is 492 pounds. Add the lighter cross members and figure around 600 pounds for the frame.

Treated 2by6's at 8' long weigh 14 pounds each. 60 2by6's X 14 equals 840 pounds.

600 plus 840 equals 1440 pounds. So about 6 barrels to float the dock around half deep. Add a couple guys on the dock fishing and you get another 2 barrels but may be too high when empty. The blue plastic barrels are just over 23" in diameter and 34" long. The dock would put the barrels about 12" or so in the water with 11" above. I wouldn't think a couple guys fishing on the dock would drop the dock more than a couple more inches. That would be for a floating dock not touching land.

The trick would be barrel placement allowing for the slope of the pond. Figuring you anchor one end on the ground you won't need to support the entire weight of the dock and the barrels would have to be in water over 12" or more deep to float. You could maybe get by with 4 barrels but I'd go with 6. If two guys are on the end of the dock fishing then I'd want 3 barrels across the end and another 3 about half way back. If you wanted the whole dock to float, then I'd still put 3 barrels on the end where people would stand which would be a total of 7 barrels or float it higher and go with 9 barrels.

This should give you an idea anyway.