Have you ever felt like improving your swimming or rowing skills but do not have anything to measure off distances? Well no need to worry; I’ve got the solution for you!

The concrete filled milk jug buoy system, as seen above, is a moderately difficult do-it-yourself contraption to create. The concrete mixture used in this Instructable is lighter than water; therefore, the milk jugs will float. Depending on the experience you have with concrete, the whole project should take 1.5 to 2 hours to complete and a couple of days to let the concrete dry.

Step 1: Supplies

The video lists and shows each supply used to build the buoy system.

The supplies shown in order are:
milk jug (need 2), rope, 0.5 to 1 mm glass bubbles, 1 to 2 mm glass bubbles, 0.25 to 0.5 mm glass bubbles, white pozzolans (VCAS-140), #16 aggregate, #8 aggregate, flyash, air entraining admixture (AEA) admixture, water reducer, K1, Portland cement, electronic scale, mixing bowl, trowel, funnel, and the lab cement mixer.

The rope can be any length you need depending on the distance swum or paddled.

Canoe 100 Meter Buoy System - Step #1
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Step 2: Safety Precautions

Before building the buoy system, please proceed with the following cautionary notes:

• Always wear goggles and a disposable respirator mask, as seen in Figure 1, to prevent irritation in the mouth and eyes from the fine particles used in creating the concrete.

• Gloves may also be worn to prevent any possible irritation of the skin.

• Don’t inhale the strange fumes from the AEA and water reducer. It makes the working area smell bad quickly.

• Keep hands away from the moving parts from the lab cement mixer while in use.

Step 3: Creating the Aggregate

To create the aggregate the K1, 0.5 to 1 mm glass bubbles, 1 to 2 mm glass bubbles, 0.25 to 0.5 mm glass bubbles, #16 aggregate, #8 aggregate will be needed. The chart above will show the needed amounts of each part of the aggregate.

Step 4: Adding the Absorbing Water

Take the newly created aggregate and transfer it to the bowl attached to the lab cement mixer and add 0.7644 lbs of absorbing water. Tap water can be used as the absorbing water. Figure 2 shows what the aggregate will start to look like right before the absorbing water is added.

Step 5: Creating the Cementuous Materials

To create the cementuous materials the VCAS140, flyash, and Portland cement will be needed. Figure 3 shows what the cementuous materials will start to look like while combining all of the parts. The chart above will show the needed amounts of each part of the cementuous materials.

Step 6: Mixing Together the Aggregate and Cementuous Materials

Take the newly created cementuous materials and transfer it to the cement lab mixer bowl with the aggregate already in it.

Step 7: Adding the Admixtures & Batch Water

While turning the lab cement mixer on, the admixtures and batch water must be added. Tap water can be used as the batch water. The water is labeled “batch” water because with the aggregate and cementuous materials mixed together create a batch.

The admixtures mixed into the batch should be 7 mL of the water reducer and 0.7 mL of AEA. Add the admixtures together and then slowly add them into the cement mixing bowl.

Figure 4 shows the buttons on the cement mixer to adjust the speed and duration (if needed) of the mixing action. To start the mixer, just press the black “start” button and continue until the concrete looks like what is in the mixer bowl in Figure 5. To stop the mixing action, just press the red “stop” button.

Step 8: Putting the Concrete in the Milk Jug

Once the bowl is detached from the mixer, use the trowel to fill the milk jug with the concrete by using the funnel.

*If the concrete stops moving, use a rod to shove the concrete down the funnel.

After the milk jug is filled with concrete, cap it and then shake it to help move the concrete into the handle of the jug. After all portions of the jug are filled with concrete, just flip it over and have it standing upside down for the next couple of days, as shown in Figure 6, to allowing the concrete to harden.

Step 9: Duplicating Steps 3 Through 8

Repeat steps 3 through 8 to fill the milk jug on the other end of the rope with concrete. The second time around should take less time; mostly because it is a repeat of what you just did.

Step 10: Tying the Rope to the Milk Jugs

The rope used in this experiment is a yellow nylon rope as shown in Figure 7. The rope needs to be cut longer than your needed length to compensate for knotting the rope around the milk jug handles.

Step 11: Cleanup and Use

Dispose the excess concrete in a proper location. The excess concrete used in this Instructable was put into a plastic container to harden and be smashed later to be used in future concrete mixing projects. Enjoy your buoy system! In the end it should look like what is pictured in Figure 8.