I made a set of very lightweight, removable thigh straps for my Alpacka Yak, to allow for better edging and control in whitewater. These straps weigh 4.4 oz, including the glue used to attach them. 2.3 oz of that is removable for trips when they’re not needed. Adding a third attachment point would add under an ounce of non-removable weight to this setup, if the two-point attachment system outlined below isn’t responsive enough for you. I’ve used this in up to class III water, which is the current limit of my skill, and I’ve used the system for up to 4 hours of nearly continuous rafting, comfortably. They provide a noticeable benefit in class II water or above. The above photo is from a 3.5 day, 91 mile trip in the Big South Fork, which was about 60% hiking, with rafting up to class III difficulty. A perfect example of where these wilderness thigh straps shine.

There are other tutorials available on how to do this, so search around and read them too. Alpacka will also retrofit your boat with their straps, if you don’t mind extra weight and cost.  My boat is a Yak, which is now known as the Classic, size medium. I’m 5ft 10in tall and I always boat wearing trail running shoes, if any of that is useful for generalizing these instructions. 

Here are the materials that I used for the project:  

• 10ft of 3/4inch utility polyester webbing from Strapworks.com $6
• 2x 3/4inch stainless steel d-rings from Strapworks.com $3 (match this size to your webbing size of course)
• 2x 3/4inch tri-glide buckles (sold as “plastic slides”) from Strapworks.com $1  (not the thin-bar type, match this size to your webbing size)
• 2ft of 1inch utility polyester webbing from Strapworks.com $2 (for ankle tie-downs; bigger surface for strength of stitching)
• 2ft x 2ft patch of packraft floor material from Alpackaraft.com $10?
• 4oz LA4123 Clifton urethane adhesive from NRS.com $30 (4oz size should handle about two of these sized projects) 
• Pro Roller hand tool 1/8in or 1/4in from NRS.com $20 (either size will work, this is reusable for other packraft modification projects)
• Strong thread for sewing machine
• Rubbing alcohol for cleaning
• Lighter
• Scissors
• Tape measure
• Sewing machine

Total: under $75 plus shipping

This was only my second sewing project, and it turned out very well. If you’re learning how to sew, this project will take you the better part of a whole day to finish. You may want to buy extra webbing to practice your bartacks on, as the sewing machine has a mind of its own with this stitch. The materials are so cheap you can buy multiples of everything, at different webbing thicknesses, to experiment with at home before you begin the build.

Construction

Singe the ends of all webbing that you cut so that it doesn’t unravel.

Using the floor material, cut out the four tie-down pieces: two for the hip area, and two for the ankle area. I made mine as small as I thought would hold up for long-term use, but I’m just guessing here (Edit: years later, this size has proven to be large enough). I used a metallic Sharpie to trace out the pattern I wanted to cut. My hip pieces are 4.75in long by 2.75in wide. You can use larger dimensions for more strength. I threaded a 3in long piece of 3/4in webbing through a 3/4in D-ring. Then I bartacked on either side of the D-ring, and bartacked again on each side for backup. I gave the webbing a slight upward bend before sewing to make room for the D-ring.

For the ankle attachment points, I cut the base to 5in by 2.25in. I was afraid that D-rings might cut into my ankles, so I used 1in webbing without a D-ring, to keep it as flat agains the boat as possible when the straps aren’t in use. The stitching on my webbing is pulling out very slightly after some use (Edit: years later, it has held strong), but it doesn’t worry me enough to think it will fail. Time will tell if I should have added D-rings here like I did with the hip attachment points, but with hindsight I don’t think that they would have bothered me with the current placement of the ankle patches. Then I cut a 3in long section of 1in webbing to attach to the base. I bartacked twice near each end, remembering to give it a bit of an upward bow so that the thigh straps can be threaded through easily when the boat is fully inflated. 

Cut two pieces of 3/4in webbing to 46 inches, perhaps longer or shorter according to your leg length. Cut one end at a diagonal and melt well to create a strong end to push through the tri-glide later. Fold the other end over and make a loop about 3 inches long, then sew it to itself using a bartack and a backup bartack. Your ideal loop length is a function of your webbing width and ankle patch webbing width, so test that you can girth hitch it before you sew these loops. Slide a tri-glide buckle onto the diagonally-cut end, and you’re ready to start attaching everything to the boat.

Attachment

See photographs for my placement of each patch. I think my placements all work well. Note the slight misalignment of the hip attachment points compared to the thigh strap webbing direction. I would align these better if I could do it over, but it’s not a big deal. Experiment with patch placement before gluing, then trace its position onto the hull with a ball point pen.  

If you can, do this outside or in a large ventilated area, because the glue is pretty gross. Fully inflate the boat. Fully. Attach the hip patches first, as it’s easier to reach them. Clean the bottom of each patch and the hull area using rubbing alcohol, then let it evaporate. Once dry, use the brush that’s built into the glue lid to brush a layer of glue onto the bottom of the patch, then set it aside to brush a layer of glue onto the boat hull. Once you’re done brushing the boat hull, the underside of the patch should be the right tackiness to apply another layer of glue to it, and then again with the hull. After a third coat on each, there should be enough glue to attach them. Then use the roller for several minutes to remove any trace of air under the patch and to help the layers of glue bond to each other. Repeat for the other hip patch. 

For the ankle patches, they’re placed awkwardly under the tubes in the front of the boat, so I did most of this with my torso bent over, upside down. Make sure they’re aligned so they’re pointing at the hip patches to reduce stress on the stitching. Repeat the same steps as above for both ankle patches. There were wrinkles in this area of my boat, so I just made sure to roller the patches thoroughly so that they follow the wrinkles of the hull. With the illustrated positioning, the ankle patches are roughly at the position of my heel, not my ankle, when paddling. I like it that way. They are mostly buried under the whitewater foot brace when it’s in use. Let everything dry for a day or two before placing any stress on the patches.  

Use

Girth hitch the thigh straps to the ankle attachment points, paying attention to the orientation of the tri-glide. Thread the free end of the webbing up through the hip attachment D-ring. The tri-glide should be in between the ankle patch and the D-ring at this point. Bring the webbing forward over the top of the D-ring, then back through the tri-glide to secure it. I like to have mine as tight as I can pull them before I put my legs into them. Test to make sure you can instantly release your legs from the straps by straightening your legs. The straps should snap (with some force) to the sides of the boat. Make sure they don’t remain in the middle of the boat ready to catch your foot. If the release doesn’t work or is janky, this modification might kill you if your boat flips and you can’t get out. Once tested on land, I’ve found that I don’t have to consciously release the thigh straps when I flip. I always come out and have never had to think about it, which is nice. 

You should find it much easier to peel into and out of eddies, as you can now edge your boat. You should also feel much more confident in rapids, as you’re not slipping around inside your boat. Consider purchasing and installing a whitewater foot brace from Alpacka. They weigh 4.2 oz and effectively make your boat shorter, allowing your knees a better bite on the thigh straps and allowing your body to stiffen the boat better, for less folding and flipping in holes. They are removable when not in use. With the removable foot brace, thigh straps, and cruiser deck, my boat can gain or lose 17 ounces of weight and be customized to do a wide range of different jobs. 

Materials Notes

The size of the webbing used is up to you. Many have used webbing up to 2 inches in width to reduce pressure on their legs during long hours of paddling, but I don’t notice any discomfort from my 3/4 inch webbing even after 4 hours of nearly continuous use. Maybe buy an equal length of 1.5 inch webbing, and test by pulling both sizes tight against your legs to see if the narrower size bothers you. If you’re not trying to shave grams, 1.5 inch would work fine and be the conservative choice. Test that your webbing size will thread through the ankle attachment points and D-rings before you glue or sew anything. 

I intentionally avoided attaching the straps to the patches using paracord, as some others have done, because I’m guessing the small cord would bite into the edges of the webbing, making premature replacement of the webbing necessary. I don’t know this for sure. 

The stainless D-rings are heavy, but I am afraid to use plastic because if it breaks then I’ve got to remove a glued-on patch to repair it (or layer a new patch over the old one), which isn’t something I want to mess with. Note that the size of D-ring used will limit your webbing choice somewhat, as you won’t want to try to string 1.5in webbing through a 3/4in D-ring. The other way around would work though.

The Clifton Adhesive is what Alpacka recommends for DIY use on their boats, if you email them to ask. I know there are other recommendations out there, but I’ll trust Alpacka on this one. My glue demonstrated a shelf life of less than a year, FYI.  If the glue is very goopy, it’s expired. It’ll look like it works, but the bonds will fail at the first decent stress. The 4oz size is plenty for this project.

I’m guessing that the roller is essential. I could almost feel the bond strengthening as I used it. I wouldn’t skimp on this tool.

You could alternatively order the floor material from DIYPackraft.com, probably.