Making a freediving neck weight

May 27th, 2009, 12:13 am
Tags: freediving neck weight

For dynamic apnea, having proper bouyancy is key to moving efficiently through the water. While some divers simply wear a weight belt as in depth disciplines, a weight around your neck will better compensate for the extra bouyancy in your lungs, meaning your body will remain level (rather than trying to swim through the water on an angle).

It is possible to buy neck weights, but why bother when it's simple to make your own?

Materials

Bicycle inner tube - mountain bike size

I used a 26x1.50 "thin" tube. I got a used one for free from a bike shop. I tested it by holding it partially inflated underwater to check for any large holes before I began. You can cut your inner tube to an approximate length before hand but leave a lot of extra for folding over at the ends.

Plastic buckle

You can get these at outdoors stores for less than $1, or just hunt around the house for something that has one you don't need.

Nylon webbing

You will need about 1/2 metre of nylon webbing, in a width that matches your buckle.

Cable Ties ("zap straps")

Lead shot

Lead shot can be obtained from most diving shops. Mine cost $3.50 per 2lb bag. You can also use small fishing weights but you might may need a larger tube as you can't pack in as much weight per volume with these.




Step One: Prepare the buckle

Cut two lengths of nylon webbing about 1/4 metre long each and pass one through each end of the buckle. Tie a knot in the webbing - try to get the knot snugged right up against the buckle. The knot will be used to secure the rubber tube to the buckle.




Step Two: Attach the first buckle

Insert the first clip inside one end of the tube, knot-end first (buckle will be sticking out the end as you are inserting it). Slide the buckle and webbing back inside the tube until the end of the tube sticks out beyond the clip by a few centimetres. This shows about how far over the buckle will be once it's inside the tube:



Once the buckle and webbing are inside the tube in the right place, put a cable tie around the outside of the tube, making sure that it lies between the buckle and the knot. Tighten it up (a lot - but not so much that you damage the tube) and cut off any excess. I recommend that you use a candle to melt off the end so nothing sharp is pointing out. Be careful not to burn your tube - or yourself!



The buckle will now be secured a little ways inside the tube. Flip the remainder of the tube (the part that sticks out beyond the buckle) inside out so that it folds back over the rest of the tube, and over the cable tie and knot.




Step Three: Add the lead / measuring

Carefully add the lead shot to the tube. Using a funnel is probably a good idea so that you don't spill. Add the lead slowly and make sure that it fills the bottom where you attached the buckle. Depending on how much lead you need and how long you want your neck weight to be, you may need to find a bigger or smaller tube. My weight is 4 lbs and it fit perfectly. Decide if you want your weight to fit you with or without a wetsuit. You don't want it too tight as it will impede your breathing, but you also don't want it to hang down too low as it will create drag when you are doing your dynamics.

I found that I was able to fit my lead in after shaking and stretching the tube a little bit. It took a bit of "packing" to get it all to fit into the length I wanted, as I wanted a fairly short neck weight (I will be using it without a suit and I have a small neck). If you need to, make two weights using thinner tubes instead of one long weight which will slow you down.

Remember when checking length that you'll have a bit of extra length due to the other end of the buckle. Be careful when messing around with the lead, it's easy to spill and hard to clean up!

Step Four: Attach the second buckle

Once you've packed your lead how you want it, slide the other clip into the open end of the tube, knot end first (same way as the other end). Try to get the knot right down to where the lead is so that there isn't a gap. Remember that the tube may stretch with time, and you want to try to keep the weight even. One thing I should have done is make sure that the two ends of the buckle were nicely aligned - I have to twist my tube slightly.



Place a cable tie in the same way as on the first end, between the knot and the clip, tighten it, and trim the end. You should have some extra tube sticking out so cut it to a reasonable length and flip it over the same way you did for the other end (will be a little trickier to do as your tube is full of lead, but a bit of stretching and you'll have it).

Done!

Your neck weight is complete! Some people choose to reinforce their weight with duct tape - this is up to you. Check your weight regularly for wear and tear, and any holes that might need patching. It's much easier to make a new weight with the same lead and buckle BEFORE it bursts and your lead goes all over the bottom of the pool!

Now get in the water and try it out =0)





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