How to make a better swimpack

Photo credit: Emily Adamczyk

You might think that making a swimpack should be a trivial task. How hard could be? You just take a dry bag, tie it to your waist with a rope and off you go swimming! This is essentially true and has been proven to work, but a couple of more considerations when making a swim pack could make your next swimming adventure much less frustrating and more efficient.

There are a few improvements that you can consider to make your next swim easier.

•  Make the bags more hydrodynamic while packing more stuff.
• Allow for convenient use on land when portaging.
• Ensure that your stuff stays dry.
• Prevent the tether from tangling in your feet while swimming.

While there may be other inconveniences that you may encounter on your next swimpacking trip my design addresses the ones listed above. However, let me know if you come up with any new ideas for my next swimpack.

To meet these prerequisites, I have designed the following features:

Compartmentalization:

My swimpack consists of two 20-liter drybags connected bottom to bottom with buckled straps when in “swimming mode”. This configuration allows to expand the volume without increasing the cross-section of the bag which minimizes the drag from the water. It also allows for easier transportation of the bag on land.

Design for portaging.

The most interesting swim packing trips that I have done involve not only swimming but also hiking or and/or bikepacking. These different modalities allow to experience the environment more fully and sometimes get into places that you wouldn’t otherwise by a single modality.

When on land you can unbuckle the two drybags and connect them in series side-by-side. Attachment of shoulder straps turns a swimpack into “hikepack”. An optional hip belt can help stabilize a slightly awkward make-shift backpack.

Watertight seal:

Video credit: Martin Cermak

Opening a swimpack after a long swim to discover all your clothes wet can ruin your trip and even put you in danger of hypothermia. Standard vinyl dry bags with thick walls provide good protection from sharp rocks and are durable but they do not create a tight seal when rolled shut. During a long swim they eventually start leaking water no matter how good your rolling technique is. To prevent this, I put a drybag with thinner walls inside of the main drybag. Thinner dry bags, seal much better and keep your stuff dry. They also do not add much weight. However, I wouldn’t use these bags on their own without the outer shell to prevent them from ripping.

Preventing the tether from tangling in swimmers’ feet.

Unless you use a very buoyant rope, the tether will tangle in swimmer’s feet. To prevent this, floaties can be attached along the tether.

Will the dry bags float if you don’t inflate them?

As long as the water does not leak into the bags, they should stay afloat based on the buoyancy of the bag contents. Normal outdoor gear, like a tent, a sleeping bag and sleeping mat and some food normally weigh much lighter than water thus, it stays afloat. Additional buoyancy may reduce drag, but I did not experiment with it. If you do, please let me know.

Now that we know what we want to build, we can start.

Materials:

• Vinyl drybags (X2)
• Thin-wall drybags (X2)
• Rope or chord (5 m, ~16')
• 1" webbing (4 m, ~13'). Don't buy cheep webbing, it will deteriorate in the sun quickly.
• 2" webbing (1 m, ~3')
• 1" buckles (male X5, female X5)
• 2" buckles (male X1, female X1)
• Small plastic carabiners (X2)
• 1" swivel snap hooks (X2)
• 1" ladder log buckle (X1)
• 1" loop rings (X8)
• Nylon fabric (<1 m^2)
• Pool noodle or an alternatively floating material. (X 1/4)
• Shoe glue
• Sewing materials

How to attach the straps to the dry bags?

To attach additional straps to the dry bags while maintaining the integrity of the dry bag walls, I sewed the straps to a patch of nylon fabric and glued the patch to the dry bag using shoe glue. This approach maintains the waterproofness of the bag while providing a strong and reliable bond. For 2 bags, make eight strap-patch workpieces – four per bag. You might get away with 3 per bag but probably not two.

Prepare the strap-patch workpieces. 

• Cut 15 x 10 cm (~6 x 4”) patch of nylon fabric. More rough fabric probably works better.
• Cut a 40 cm (~16”) long piece of nylon webbing and sew an extra loop of webbing with a plastic loop put through it. (optional) (See figure 1). This plastic loop will be useful for attachment of the portaging strap, the shoulder straps or the hip belt. I was lazy, so I put this loop on only half of the workpieces. If you’re lazy like me, just make sure to place the workpieces with the loops on the sides of the bags that will end up on the outside edges of the backpack.
• Sew the webbing to the fabric patch as shown in figure above. Make sure to not sew the nylon webbing to the fabric all the way to the edge of the fabric patch so that when it is glued to the bag it doesn’t peel off easily.

After all the workpieces are ready glue them to the bags. Make sure to score the nylon bags at the place of attachment with sandpaper or a knife before applying the glue. Follow the instructions from the glue manufacturer. I used this product that I spread out in a thin layer on both the bag and the workpiece, dried it out for a couple of minutes stuck the two pieces together and applied pressure for 24 hrs. I glued two workpieces per bag on one side at a time.

After the glue is dried the straps should be well attached to the bag. You can now add the quick-release buckles to the straps. Add end stops at the ends of the straps to prevent losing the buckles (figure). Make sure to check the proper orientation of the buckles BEFORE you sew on the bar tacks.

End stop

Make the tether:

Tether

A tether will consist of three parts. A waste band with a quick-release buckle, a rope with floaties and a bag attachment with two carabiners for tension distribution. A waste band allows the user to release the bag quickly in an emergency. The rope floaties will prevent the tether from tangling in the swimmer’s feet. The tension distribution carabiners will prevent the bag from tilting diagonally thus reducing the drag.

First, measure the length between your hip to the tip of your toes plus two feet. Optimize the length of the tether so that you can’t kick the bag but it is also not too far away so that the current produced by your body while swimming can help to drag the bag. Remember that you can always make the rope shorter, but not longer so don’t cut the rope too short.

Now it’s time to attach the floaties to the rope. Determine the location of the rope that will be hanging over your heels when swimming. Measure one foot above and below that location. This is the segment of the rope where the floaties are going to be attached. Tie a knot at one end of this segment. String a short piece of a pool noodle up to the knot. Lock that piece of pool noodle with another knot. Repeat this process two or three more times. Add a final knot to lock the last floaty in place.

To make the tension equalizer cut out another 50 cm (~20”) of the rope. Tie the middle of this shorter rope to the rope with the floaties. Make sure to tie it to the side of the rope with the floaties. Tie two carabiners to both ends of the shorter rope. Adjust the middle knot so that the shorter rope can freely move through the knot but won’t allow the carabiners to slip through it.

The last part is the hip belt. Make a simple belt out of nylon webbing and quick-release buckles. Tie the end of the longer rope to the middle of the hip belt. Do not forget to add end stops at the ends of the webbing to not lose the buckles.

The swimpack is now fully ready for swimming. It only needs shoulder straps and a hip band to carry the backpack on your back when hiking.

The shoulder straps.

I bought mine at MEC. However, I’m sure you can find some at REI.

The hip band.

I made my hip band out of a wider piece of webbing for better comfort. The ends of the belt attach to the plastic loops on the bags through the plastic carabiners. The tension adjustment is possible through the quick-release buckles.

The hiking mode strap.

This strap will be used to tie together the two bags next to each other when hiking. Measure the circumference of the two bags standing together side by side plus some slack. My strap is 140 cm (~55”). Sew on a ladder log buckle onto one end of this strap. Leave the other end of the strap as is because it needs to pass through the loops on the bags.

Operation:

Swimming:

• Line the thicker dry bags with thinner dry bags on the inside. (Note: Do not put your stuff into the liner before you put the liner into the main bag because it may not fit into the main bag with all the stuff in it.)
• Place all your stuff into the inner liner and shut the dry bag. Leaving some air pressure on the inside could be beneficial for a better floatation. A deflated bag can also serve as an indication that the bag may be leaking.
• Roll shut the outer bags. Try to roll both bags in the same direction so that the buckles stay out of the water when swimming. This will reduce drag and water leaking inside.
• Attach the two bags bottom-to-bottom using the glued-on straps. Tighten the straps and adjust the tension in the straps to make the bag profile as straight as possible. (Note: A slight bend in this assembly might lead to the bag steering off course creating a lot of drag.)
• Put on the tether belt and attach the tether carabiners to one of the bags.
• You’re ready to swim!

Hiking:

• Place the two bags next to one another side-by-side in the same orientation.
• Tie them together with the hiking mode strap. You can put this strap through the plastic loops that you added to the bags earlier.
• Attach the shoulder straps to the tops of each bag. This will serve as an attachment for the shoulder strap and as another point of attachment between the bags.
• Clip the hip strap into the plastic loops on the bags.
• You’re ready to hike!