I just finished building an 8'x16' floating wharf. I chose that size for economy and ease of building, and it should be just big enough for my needs. I used 10 blue plastic drums for flotation, and 5 fits nicely within the 16'length. The drums were easy to come by through my wife. She works at a dialysis clinic, where they purchase acetic acid (medical grade vinegar) in them.
When the treated wood was delivered, I noticed it was fairly straight, as treated lumber goes. It was all slightly but equally long and out of square. I had to make a decision on whether to square off all that big 2X lumber, or use it as is. Since the 2x12's were out of square by only 1/8" over 11-1/2", I decided to use it. Nobody would notice it but me, and it would save me a lot of time and work. Nobody but us knows that every board is slightly out of square, so let's keep it our secret, OK?
I built the wharf on the ground, on an end of the pond where the levee is 50' wide and pretty flat. The 2 perimeter and 3 inner joist's went together very quickly, despite working alone. I paid special attention to keeping things flat and square, and kept the perimeter 2x12's eyeball straight. I squared up, checked and re-checked, then diagonally braced everything together with 8' 2x4's until I was satisfied. The Torx head stainless steel screws proved to be very soft, and were easy to twist off. I had to set my drill driver's torque adjustment just short of breakage. The decking part went more slowly. I spaced the planks at about 5/16", and fudged occasionally to return them to square. I tried to keep the crowns up, but an occasional knot hole forced me to face the crown downward. I used Gorilla glue for rigidity, and learned to it judiciously, as it expands 3 times. I advise using blue Nitrile gloves when using it, as it's very tenaceous, and stains your hands terribly.
Once finished with the building, I got help to launch the wharf. I ran a single 20' sling around it at the balance point. Using a chain and slip hook, I hoisted it up with my trusty little tractor. I moved it into place, and lowered it down close to the pond, stopping about 18" above the water. As usual, I am kicking myself for not bringing my camera along. The little tractor hauling the wharf balanced on a single sling was quite a sight. My intrepid No. 2 son volunteered to wade into the pond, and shoved the 10 barrels in between the perimeter joists. The joists were spaced precisely for the drum diameter to fit snugly. Total building and deployment time was about 10 hours.
I am delighted with the results. The little wharf looks just fine to me, but you be the judge. It's solid as a rock. The decking hardly yields when I bounce up and down, and the flotation has enormous reserve. The only problem is, the 2x12 joists are a little too wide. The wharf rides only about 5" above the water line. When I stand on a corner, the wharf tilts a bit, and the corner barely touches the water. This is probably harmless, but I would rather keep the wood dry at all times. When I stand way out on the end, it still rides a good inch above the water line. When I stand on one of the sides, it hardly moves at all. In retrospect, maybe I should have used 2x10's for the joists. They would have added 2" of extra freeboard, and would have been plenty strong. The 2x10's would also have saved ~100 lbs off the wharf's ~1000 lb weight, and it would have floated perhaps 1/4" higher. I may decide to add rails and/or lamp posts for night activity. I can't wait to see how fishing poles, lawn chairs, and an ice chest look on my floating wharf.
Here's the bill of materials:
10 ea free plastic drums
5 ea 16' treated 2x12 for perimeter and main joists
2 ea 8' treated 2x12 for perimeter ends
33 ea 8' treated 2x6 decking
2 ea 8' 2x4 studs for bracing
5 lb 10x3" ss screws - deck fasteners
25 ea 10x3-1/2 ss screws - perimeter fasteners
8 oz Gorilla Glue - perimeter, decking, barrel bungs
4 ea 1/2x4" eye bolts and nuts for roping off
2 ea 16" screw-in ground anchors
25' 3/8" poly rope
Cost ~$400
Since I know Eddie will ask for pictures, I ran out this AM and took some. The weather was dreary, so excuse the dullness.
Dreary weather, but smooth water
A longer shot
Excuse my hasty gangplank. We will need a better one.
1 of 4 eye bolts for tieing it off.
