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How to Fill a BOB Punching Bag

Last Updated: 04.07.22


A Body Opponent Bag or a BOB punching bag is a piece of great equipment to have for your training sessions. As the name says it, this punching bag has a shape that resembles the human body. It even has a mean-looking face in order to motivate you to hit it harder. Unlike other punching bags that you can purchase, these only need filler for the base, and you can add some of your own for cheap. 


What is a Body Opponent Bag punching bag made of?

The “body’s” outer shell is made of plastisol. Plastisol is a high-strength material preferred by manufacturers because it simulates the feel of punching a real person.

The inside of the punching bag is filled with high-density urethane foam padding. Producers opted out for this foam in order to obtain a uniform hardness. Despite not being as hard as other traditional punching bags, you should still use gloves when training in order to avoid getting injured.

There are a few things to consider before starting to improve your kicks and punches. First of all, a Body Opponent Bag will be delivered with an empty base. This could be a good thing since it leaves you the choice of what base filler to use.



Which option is the best?

There is no answer to fit all the possibilities. Some athletes use water, sand, or even rocks in order to increase the weight. The right choice depends or the training surface, fighting style, experience, and training purpose.

As a general rule, don’t attach the superior part before filling up the base. This will allow you to move the BOB punching bag around easily, saving you time and effort.


Filling the punching bag’s base with water

This is the fastest way to set up your punching bag. Using a bucket or a gardening hose should fill the base in a matter of minutes. Water has the advantage of availability. It doesn’t matter if you are at home or at the local gym. There is no need for a trip to the local supermarket in order to get your much-needed base filler. 


Always check the base for defects

Defects might be caused by careless maneuvering during transport or it could be a manufacturing defect.

Before filling up the punching bag’s reservoir you should check if the plastic doesn’t have any damaged areas. Take a close look at the punching bag’s tank. Also, you could use your hands to detect any irregularities in the base surface to see if the punching bag wasn’t damaged during transport. 

Another method implies using a flashlight. Turn off the lights and place a turned on flashlight inside the reservoir’s filling cap. If you see any ray of light exiting the tank, you should ask for a refund.

Even if your new training equipment seems to be in top condition, you should still pay attention while filling up the base. Furthermore, keep an eye on any possible leakage after setting up the bag. 

Since water doesn’t have a high density, your Body Opponent Bag might be a bit lighter than you need. If you are practicing powerful strikes, the bag will move around the room. Also, be careful not to knock over the punching bag as this may cause small cracks in the punching bag’s tank.

Some athletes recommend fixing the punching bag to one of the lower height settings if you are using water as a base filler. If it is set up at its maximum height (around 6 feet 6 inches) it will easily tilt over because of its reduced weight.

According to a piece of information that could easily be found online, if the base is filled with water, the BOB punching bag should weigh around 200 or 240 lbs. 


Preparing the Body Opponent Bag for storage

Furthermore, water is a good option if you need to store away your punching bag. Emptying the base should cause you no problem despite not having a drain pipe placed at its bottom. If you are living in a colder area, make sure to empty the tank before putting the BOB punching bag away. As we all know, water expands when freezing and it will cause the base to crack.

Not only this will ruin your training equipment, but the leaking water might damage some of the other goods placed in storage. Keep in mind that it takes around 20 gallons of water to fill the tank.

What to do if the reservoir starts leaking

Even if water starts to leak from the bag’s tank, you could still use that Body Opponent Bag during your training sessions. You just need to replace it with another base filling material.


Using sand to fill the punching bag base

We recommend replacing the water with sand. Empty the water from the reservoir and wait a couple of hours for it to completely dry. Pour as much sand as you need. If you want the bag to have the same weight, fill up around three-quarters of the base.

As an additional safety measure, place some duct tape over the fissure, to keep the sand from escaping the base.

Nevertheless, sand is a better choice if you are looking for a heavier, more stable Body Opponent Bag. You should consider using sand only if you don’t plan on moving the punching bag around every couple of days. Keep in mind that the bag’s tank will be heavier than a water-filled plastic base.


Filling up the base

The most tedious part when buying a new punching bag is having to set it up. In order to avoid buying too much or not enough sand, you should check online the punching bag’s specifications. According to some producers, you will need around 250 lbs of sand to fill up the tank. It should be around 4 bags of sand at the local supply store.


How to avoid making a mess

We recommend going outside in order to fill the reservoir as it might get messy. If you have no other choice than to do it inside the house or the gym, you should place a canvas underneath the bag. 

Filling up the tank using sand might be a difficult task since the filling gap is pretty small. Depending on your technique, this will take you from several minutes to a few hours. You could use a big spoon or a glass in order to avoid spilling sand all over the floor. But it will take you hours and you probably want to start training as quickly as possible.

How to fill up the base as fast as possible

No fancy or expensive tools are required for this task. Use a big funnel and pour the sand directly from the bag. You should ask someone to help you as it will be harder to maneuver the sandbag using only one hand.

For the second method, you will need two plastic bottles. The bigger the better. Remove the caps and cut out the bottom of each bottle. Take one and place it in the filling gap. The second one will be used to scoop up the sand and pour it into the other plastic bottle. It will be even faster if someone is helping you.


Keep the sand dry

Make sure to deposit or to pick up dry sand. If the sand is dry, it will flow effortlessly into the tank. After filling up the punching bag’s base, make sure to tighten the cap so moisture doesn’t get in. If moisture gets in, the sand will set into a form almost as hard as concrete. This will make it very difficult to get out the sand out before moving the bag to a new location. 

This is why you shouldn’t use sand as a base filler if you plan on training outside. The rain or snow could ruin your training equipment.


How to increase the Body Opponent Bag’s weight

You filled up the bag with sand and it still seems a little bit too light for your powerful punches. If this is the case, you should consider adding small rocks into the base. In case you want to go for a really heavy training bag, you should add in layers of sand and small rocks. Remember to start with a layer of sand in order to avoid additional wear caused by rocks.

Another good option is to use gravel as it settles better than irregularly shaped rocks and it is easier to pour.




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