[BOBBY] Hey guys, I’m Bobby from the Canberra Underdogs… …and today we’re going to learn about how to fill an underwater rugby ball. With me here, I’ve got Dan. Dan just started playing underwater rugby three months ago, so he basically knows nothing. But that’s good, because if Dan can learn how to fill an underwater rugby ball, then you can too! So first off, you’ll need a pressure sprayer, and a needle from a ball pump. You can get one of these sprayers from a hardware store. You’ll also need a 2mm hollow metal tube… …and an optional solid metal rod that can slide in and out of the tube. Next, you’ll need a measuring tape, a thermometer, and a cordless drill with a mixing attachment. This particular attachment is called a paint mixer, and you should be able to get it from a hardware store. You might want a set of kitchen scales to help you weigh the salt. Use normal kitchen salt because it’s easier to dissolve. And of course, you’ll need some empty underwater rugby balls. Last but not least, you’ll need a kettle and a large bucket. First, you’ll need to set up the pressure sprayer. Make sure it’s at least 5 litres in capacity. Also, make sure it comes with a rubber hose. Remove the sprayer mechanism from the rubber hose, and then insert the ball pump needle. To secure the nozzle onto the hose, you can use a cable tie, or a stainless steel hose clamp. This step is optional, but it will stop any leaks, and make the whole process a little bit easier. Next, you will need to prepare the hollow metal tube, which will be inserted into the ball later. Use some fine grain sandpaper to sand down the ends of the tube, so you don’t put a hole in the ball. Look at that smooth edge right there! Now, for some science. You’ll need to calculate the correct ratio of water and salt. The standard ratio is 360 grams of salt to every 1 litre of water. So, if you have 2 kilograms of salt, you’ll need around five and a half litres of water… …and that’s just about enough to make two rugby balls. If your salt doesn’t come pre-measured in a packet, you’ll need to weigh it with your kitchen scales. So now, just empty your bag of salt into the bucket, and boil some water. And don’t forget to keep track of how much water you’ve got there. While you’re waiting for the water to boil, take out as much air from the rugby balls as you can. Use some dishwashing liquid to lubricate the needle so it doesn’t damage the valve. Slowly insert the needle into the ball and squeeze out as much air as you can… …and then gently take the needle out. Next, attach the agitator (or paint mixer) securely to the drill. When you’ve boiled all the water and poured it into the salt, it’s time to get mixing! Mixing the salt with the hot water can be a very messy process, so we recommend you do this in the shower. After about 2-3 minutes, you can stop mixing and use the thermometer to take the temperature of the water. When the water temperature drops to about 60 degrees Celsius, it’s time to pump those balls! In the meantime, don’t forget to wash the agitator and the mouth of the drill to stop them from rusting. Now you can pour the warm salt water into the pressure sprayer. Make sure you don’t pour any leftover salt at the bottom of the bucket into the sprayer. Carefully insert the needle into the ball and start pumping. When the ball gets to at least 46 centimetres in circumference, release the pressure from the sprayer… …and take the needle out. You’ll probably notice there is a pretty big air bubble inside the top of the ball. So next, get the hollow tube, and slide the rod inside the tube. The rod is optional, but it might prevent hot, salty water from spraying you in the face. Slowly insert the tube into the valve and push it all the way through… …so you can feel it on the other end of the ball. Now, you can turn the ball upside down and start removing the rod. And as you do that, you’ll hear the air escape. Wriggle the tube around in different directions, until you’re pretty sure there’s no more air left inside. Now shake the ball around, close to your ear… …and when you can no longer hear the air bubble inside, you can start taking out the tube. Before you insert the needle into the ball again, it’s important to make sure the water is already flowing… …so you don’t push any more air back in. Continue filling the balls until you get to between 49 and 51 centimetres for women… …or 52 and 54 centimetres for men. When you measure the ball, make sure you’re measuring around the valve. It’s perfectly normal for the balls to be about 1 centimetre longer around the valve side… …than they are around the equator. When you get to the circumference you want, take the needle out, and check again for air bubbles. If you do need to let some more air out, make sure you put some water back in… …and get it back to the circumference it was at before. And then when you’re done, give everything a good rinse and wash the sprayer thoroughly… …to stop it from clogging up with salt. And the next step is to test the balls! [BOBBY AND DAN] And that’s how you fill an underwater rugby ball!