How to Build a Floating Dock With Barrels as a Platform

A few years ago, I built a floating dock out of treated wood using barrels purchased from a recycler. To maximize the use of this new dock, I wanted it to be usable as a floating platform for my older teenagers who want to swim in the middle of the lake.

However, there are several rules to follow to make your construction successful.

Maximize the number of barrels

You need to maximize the number of barrels to prevent your dock from becoming unstable. If you skimp on the number of barrels, when 4 or 5 people stand on it, diving into the water, you will see your creation swaying and the barrels leaving the ship.

No need to tie the barrels down

By putting as many barrels as possible, the barrels will never move or come loose from your platform. You will not need to tie your barrels with steel bands if your uprights are wide enough, i.e., 10 or 12 inches (25 or 30 cm). In fact, after a few years, these steel straps will soon rust and break.

Sealing the barrels

Always choose 45-gallon (205-liter) rigid plastic drums with one or two twist-off caps. Be sure to seal the caps with silicone bath sealant before screwing them on. This sealant will resist leaks for many years, preventing your barrels from leaking.

Avoid barrels with large lids, screws, or large steel hoops, which are unsuitable for this type of work and will eventually corrode and leak.

Measuring your barrels

Typically, 45-gallon (205-liter) barrels are 36 inches (90 cm) high and 24 inches (60 cm) in diameter. You will use these measurements to build the formwork for your dock.

Calculate firmly

In order to prevent your barrels from moving during high winds, freezing, and thawing in winter or while several people are sitting in them, it is recommended to stabilize them directly in the formwork of your dock.

Let me explain. The number of barrels in length will determine the length of your dock, while the number of barrels in width will determine the width of your dock. Simple. Don’t forget to add in your calculation the thickness of the 2 ft (5 cm) x 10 ft (25 cm) uprights and a 2-inch (5 cm) set of pads to slide your barrels.

In width: calculation for 3-4-5 or 6 barrels

3 barrels x 24 ft (60 cm) + 3 pads x 2 ft (5 cm) + 4 uprights x 2 ft (5 cm) = 86 ft or 7.2 feet (215 cm)

4 barrels x 24p (60 cm) + 4 pads x 2p (5 cm) + 5 posts x 2p (5 cm) = 114p or 9.5 feet (285 cm)

5 barrels x 24p (60 cm) + 5 pads x 2p (5 cm) + 6 posts x 2p (5 cm) = 142p or 11.8 feet (355 cm)

6 barrels x 24p (60 cm) + 6 pads x 2p (5 cm) + 7 posts x 2p (5 cm) = 170p or 14.2 feet (425 cm)

In length: calculation for 2-3-4 or 5 barrels

2 barrels x 36p (90 cm) + 2 pads x 2p (5 cm) + 3 posts x 2p (5 cm) = 82p or 6.8 feet (205 cm)

3 barrels x 36p (90 cm) + 3 pads x 2p (5 cm) + 4 posts x 2p (5 cm) = 122p or 10.2 feet (305 cm)

4 barrels x 36p (90 cm) + 4 pads x 2p (5 cm) + 5 posts x 2p (5 cm) = 162p or 13.5 feet (405 cm)

5 barrels x 36p (90 cm) + 5 pads x 2p (5 cm) + 6 posts x 2p (5 cm) = 202p or 16.8 feet (505 cm)

Make a plan

It is essential to draw a plan to calculate the number of barrels and the amount of wood needed to build your dock.

Calculating the number of barrels

Looking at the measurements above, let’s say you decide on a dock that is 11.8 feet wide (5 barrels for 142 ft or 355 cm) by 13.5 feet long (4 barrels for 162 ft or 405 cm). You would then need to buy 5 barrels wide by 4 barrels long, i.e., 20 barrels. Each barrel will cost you about $10, which you can find on used product sales sites or at recyclers. Cost approx. $200

Calculating wood for studs

I use only weather-treated wood, which is more expensive but will last for decades. The sides and interior posts will be 10 or 12 inches (25 cm) x 2 inches (5 cm), while the floorboards will be 4 inches (10 cm) wide. So for our 5-barrel wide x 4-barrel long dock, here are my wood stud requirements:

For 5 barrels wide: 6 posts of 12 feet (360 cm), 10 ft (25 cm) x 2 ft (5 cm)

For 4 barrels long: 5 posts of 13.5 feet (405 cm) of 10 ft (25 cm) x 2 ft (5 cm)

In 2012, the best price for a 2 ft x 10 ft x 12 ft upright was $10, and the 14 ft was $12. The total wood for the amounts will cost you approximately $60 + $60 = $120.

Calculating the wood for the floor

If your dock measures 12×14 feet (360×405 cm), and you calculate a space of 1 inch (2.5 cm) between the 2×4p (5×10 cm) boards, then count 30 boards of 14 feet (covering 120 inches by 144 inches) at $3 each = cost of $90

You will need to calculate the treated wood screws, steel wedges, and rings to attach your boats for about $25. For a total project cost of approx. $500 with taxes.

Transportable construction

If you decide to build your dock in your garage or workshop a good distance from your lake, remember that you must move your work. You can place it on a trailer with no sides or build it all on the shore of your water.

You can move it like a coffin if you have several strong arms (a good dozen).

Quick and easy

This project is relatively easy to do. I completed my dock alone over the weekend. It will last for decades and will be the pride of the neighborhood. All aboard!