There are times when a wearable throw bag is preferable to a carried one. Usually when you are working around swift water and you need both of your hands; portaging, lining, tracking, etc. When you need both of your hands and are concentrating on the a specific task a throw bag is just another annoyance but if you can clip it safely around your waist until the task is done at least you at least still have it close by when it all goes south for someone in your group. Normally I don't recommend extra loops and belts on a throw bag but the throw bag is no good if you don't have it with you. Imagine portaging your canoe around a waterfall and your partner slips and falls in above the falls, but you left the throw bags back with the gear.
A wearable throw bag is no different than a regular throw bag except it has a belt strap on it. The fabric to use is a highly visible nylon Cordura.
The first thing you need is fifty feet of 3/8 floating rescue rope. This will cost about $15 in Canada. You will also need a sewing machine, a measuring stick, some scissors, a couple grommets and setter, heavy nylon Cordura fabric, and some nylon strapping. Some other basic sewing supplies will make this project a bit easier too. I got a deal on my fabric; I got about 2 meters for under $5; enough to make 20 rescue bags. Nylon strapping is pennies a foot.
Cut your fabric 15 by 18 inches and measure from the top 6 or so inches down and draw a line with a fabric pen or a sharpie marker. Then draw in a center line from the bottom to the line at the top. These are the center lines for attaching your nylon web strapping.
Sew down the nylon belt and be sure it is long enough to go around you and maybe the fattest person you paddle with. For extra strength at the ends I sew in a "W". This is what is used for making western saddles at stress points where strength is needed. Leave an inch or so at the bottom so it is easy to sew the final fabric in down there. Also stop at the top line to allow for the top of the bag to gather properly.
Sew in the extra security straps to keep the belt from ripping off and to give the whole bag extra strength. Stay back from the edges a half an inch so it is easier to sew the seam when you finish up the bag.
Fold the bag inside out and sew up the side. Spend a few extra seconds going over the nylon strapping so it is good and secure. Trim off any extra strapping so it does not catch your rope and snag it during use, then melt the ends smooth with a lighter or candle.
Sew in the end fabric. It should be a piece of round fabric with about a 5 inches in diameter. This is the only hard part. Be sure to put the outside of the fabric to the inside and sew slowly. You may want to pin the bottom into place to make this easier.
So now you want to add the draw string. Turn your bag right side out and sew a small piece of nylon strapping about an inch down from the top and put your grommet in there. The nylon strapping will reinforce this area as it gets the most use. If you have a good hole punch you can use that but a hot metal spike will melt the hole pretty quick too. Turn the bag inside out again pull the two ends out your grommet hole and roll about an inch and a half hem. Keep the draw string away from the sewing machine needle up under the hem and sew the hem flat just under your grommet.
A 3/8 inside diameter grommet goes into the bottom for the rope to come out of. You can reinforce this on the inside if you like. Pull the rope through and tie a bowline knot.
All throw bags need a closed cell foam float and a washer to keep the foam in place. Put a hole in the center of your foam float and slide it down the rope into the bottom of the bag followed by the washer and seal it with a knot.
Stuff the rope into the finished throw bag and adjust the belt to your size. Note the "W" stitching for strength.