Introduction: ADAPTIVE PADDLING FIXTURE FOR KAYAKING
First Prize in the
Humana Health Challenge
My adaptive paddling fixture for sit-on-top kayaking is (aguably) the most successful design created to date, being reproduced by univerities, inclusive recreational and physical therapy providers, and other such organizations across the United States and around the world.
Those unfamiliar with the capabilities of many adventurous outdoorsmen (and women) facing serious disabilities, may be surprised to hear that this fixture is designed to assist quadriplegics who have limited use of their arms and possibly little, if any, ability to grip with their hands. This fixture also proves especially useful for a paddler that has good use of only one arm and hand!
I put all my designs in the public domain so they can be freely reproduced, even for profit, and noone may patent them to preclude others from fabricating them and perpetuating their use.
Together with my seat adaption, shown in the photos below (and the subject of a future Instructable), this combination has safely brought the freedom, adventure, and inclusion of the wonderful sport of kayaking to hundreds of participants.
The Paddling Fixture is easily constructed with a minimum of parts and a total cost well under $100. The hardest part of the design process is making a few 90-degree bends in the aluminum braces that hold the base of the boom to the deck plate.
The design, as presented in this Instructable, is specifically tailored for use on an Ocean Kayak, Inc. Malibu Two model. The M2 is, to date, the best selling kayak in the world and the model most often found to be available at rental outfitters. This design is Plug & Play to a stock Malibu Two, requiring absolutely no modifications or additions to the kayak.
Modifications to this design for adaption to another kayak model may include one or both of: Changing the Base Plate (white, in the first photo below) in shape and/or method of attachment to the kayak, or changing the length of the Boom (shown as 48 inches in length in this design). The rest of the design would remain unchanged.
The List of Materials is quite small, so I'll simply present them as they are encountered in the build process. With that said, let's get started...
Step 1: BASE PLATE
The design of the Base Plate, as shown, allows for its fastening to a stock Ocean Kayak, Inc. Malibu Two kayak without any modifications or additions whatsoever to the kayak. This means that a rental kayak could be used to provide an awesome day out on the water for the paddler. Slight modifications to this design should allow it to be adapted to just about any sit-on-top kayak. Later, I'll present some alternative designs for other kayaks as well as decked (sit-inside) kayaks.
From a roughly 33 inch by 27 inch piece of plywood, 1/2 to 3/4 inches thick, mark and cut the pattern as depicted in the first drawing below.
For the Malibu Two, the critical dimensions are: (1) 16 inches wide where the front deck strap fits into the forward area of the Deck Plate, (2) 29 1/2 inches length between the center of the strap features and the hole where a large tie-wrap secures the rear-most features of the Deck Plate to the kayak, (3) 22 inches between the holes that get tie-wrapped to the factory placed eyelets on the M2, and (4) 23 max inches from the strap to the rear edge of the main part of the Deck Plate ensures the entire footwell area of the cockpit remains open. Simply mark these critical dimensions onto the wood or pattern first, then fill in the rest approximately as shown.
It is helpful to draw one side (left or right) of the pattern on a large sheet of paper and fold the paper along the center-line. Then cut out the pattern for a perfectly symmetrical design.
The CAD drawing below shows that several sets of holes are pre-drilled into the Deck Plate to facilitate adjustable longitudinal placement of the Boom Brackets. This will be discussed further later on.
Note that the first photo shows an earlier Boom and Boom Bracket design that incorporated a few extra parts. The adaption presented in this Instructable presents the latest design using the fewest possible parts.
Step 2: BOOM BRACKETS
Next in the design are the Boom Brackets. These are fabricated from an approximately .090 to .125 thick sheet of aluminum according to the dimensioned diagram below. You will need to specify a softer aluminum that will accept a fairly tight 90-degree bend without cracking. 5052 or 6061 in T3 hardness should work.
The drawing below pretty much illustrates how the Boom Brackets fit into this design. Of note are that the Pivot Pin and Support Pins are 1/4 inch X 2 1/2 inch stainless steel bolts. I use Wing-Nuts to facilitate rearranging and tightening of the bolts in the field without need for hand tools.
The Pivot Pin stays rather snug during use and the Down-Position Support Pin is tightened after the paddler is onboard and the Boom is lowered into position.
Assemble the Boom Brackets to the Boom first (to set the spacing), then place this assembly onto the Base Plate in order to define the pre-drilled hole positions in the Base Plate. The Boom Brackets are secured to the Base Plate with 3 wood screws each. Use the largest that will fit, but not protrude throughthe Base Plate.
Step 3: BOOM
This brings us to the Boom... The Boom is cut from a 2 inch thick by 48 inch long piece of Ash wood. Ash is the same wood that bows (think bow and arrow) are made of and provide great performance in the marine environment as well as the flexibility the design requires.
The Boom is cut on a precision band-saw. It runs an inch thick for about one foot, then tapers evenly down to 3/8 inch.
The hole near the very end of the thick end is required, and the additional holes placed at 1 or 2 inch intervals are optional to allow further adjustability of the distance between the paddler and the paddle. Note that using holes farther from that end of the boom may necessitate an opening in the Base Plate for the Boom to swing down into when it is moved to the raised (boarding) postion.
Step 4: PADDLE LOCK
The Paddle-Lock is what makes my Adaptive Paddling Fixtures work!
The Paddle Brace that the paddle is taped to can be made from just about any material that can be cut on a wood-working band saw of machined in a mill. Fabricate this part according to the dimensions shown in the drawing below.
The critical dimensions for this part are (1) 1 inch width so it operates without too much play within the sides of the Swivel Caster, (2) the 1/4 inch axle hole to fit the axle without wobble, and (3) the 1/2 inch radius of the groove that the paddle shaft fits into, so the paddle can be taped firmly to the Brace.
Buy these 2" swivel casters at any home improvement store. Look for models utilizing a bolt and nut for the axle. You can reuse the axle in this design, or substitute a rather expensive quick-release pin to fascilitate easy removal of the paddle from the fixture. Also look for swivel caster models that have four holes in the base plate rather than a single bolt protruding from the base.
Mark the pattern of two opposing mounting holes onto the Boom and mount the swivel caster to the end of the boom using 1/4 inch bolts that are as short as possible. Shorter bolts reduce the possibility of snagging the paddler's clothing.
Step 5: MOUNTING THE PADDLING FIXTURE
Referring back to the first photo...
Attach the Base Plate to the kayak first using the existing forward strap. Some experimentation with the strap length adjustment will allow you to just snap the buckle together while causing the strap to firmly hold the front of the Deck Plate in place.
Use heavy-duty Nylon tie-wraps to secure the factory installed eyelets of the kayak to the holes in the Deck Plate that they line up with. Pull the tie-wraps tight. The Deck Plate should now feel pretty firmly attached to the kayak.
By now, you will have semi-permanently mounted the aluminum Boom Brackets to the Deck Plate centered along the center-line of the Deck Plate and at the exact width of the Boom.
Secure the thick end of the Boom into the Boom Bracket and let the Boom rest on the Support pin in the lowered position. Place the unfeathered Paddle onto the Paddle lock and posiiton it exactly perpendicular to the centerline of the kayak as shown. Roll the paddle such that the blades are exactly perpendicular to the ground. Also, position the paddle such that it is centered left and right with the Boom and not the swivel-caster. Securely duct-tape the paddle to the Paddle Lock, wrapping first in one direction, then in the other as required to maintain the blades perfectly perpendicular to the ground.
Note that the perpendicular orientation of the blades to the water is essential to keep the blades from diving or climbing during the paddle stroke.
Step 6: USING THE PADDLE FIXTURE
Note that the photo attached to this section shows an earlier version of the Malibu Two design (yellow kayak) as well as the design adapted to an Ocean Kayak, Inc. Scrambler XT (turquoise kayak).
It will be up to the paddler and assistants, and the launch location, as to whether the paddler is boarded onto the kayak before or after the kayak is placed onto the water. In most cases, we have found that it is best and easiest to board the paddler before launch. Some care must be taken when sliding the kayak with boarded paddler into the water off of a low floating dock, however, beach entries are a "no-brainer".
The Boom, with paddle already attached, is set into the raised postion, and while ensuring that the Boom and paddle will not fall onto the paddler, the paddler is placed aboard the kayak. Adjustments, as necessary, are made to the seat and PFD, ensuring a comfortable and stable postion for the paddler. Look for a future Instructable on my Adaptive Kayak Seat design for more discussion of this.
With the paddler's permission, the Boom is lowered and tightened into the paddling position and the paddler is ready to go.
Please remember that there is a slight danger of getting caught up in the boom and padddle in case of a roll-over, particularly for the highly disabled paddler. In the few experimental roll-overs I personally have tried I have not experienced a trapping situation. I still highly advise that the disabled paddler be accompanied, and monitored closely during trials by an able-bodied paddler who is a confident swimmer, and possibly even trained as a rescue diver or lifeguard. I also suggest that you make use of low profile hardware at the 'paddle-lock' that is unlikely to snag clothing.
Other safety concerns are present when gearing up and fitting the paddler to the kayak. EVERY individual has different abilities and requirements for participating fully and safely. It is very important to have the expertise of one who is familiar with the various techniques that are used for fitting the man to the machine (as it were), perhaps one of the disabled paddlers themselves! Simple things, like a swivel-snap left under a seat cushion, can cause serious abrasion-type injuries that may take months to heal in areas of reduced circulation. The paddler may often require additional foam padding (often fitted on-site) or a particular placement of an additional life-vest in order to have the support he or she needs to paddle the kayak with the least effort and greatest stability. All pressure points, such as eyelets, which cannot be removed from the kayak should be well padded before leaving the dock or beach.
About the photo: Jane had extremely limited control of her upper body and was unable to control the paddle with her hands. At her first outing, I quickly reconfigured my fixture on the dock to allow her to get her feet up onto the paddle. After three outings, she was paddling a couple miles round trip, out into open water, and beyond the outer jetty and back. On the turquoise kayak, Jack is an incomplete quad with limited grip and ability to push with his arms. Jack is a regular on these outings and an avid scubadiver as well. On the dark blue kayak, Denise is an HSA (Handicapped Scuba Association) scuba instructor and an occupational therapist living and working in Santa Barbara. Denise has been my mentor and kept me out of trouble in these endeavors for over 15 years!
Step 7: ALTERNATIVE DESIGNS
The photos and drawings attached to this step present a few of my other Adaptive Paddling Fixtures that have been reproduced and utilized with great success.
The two designs, apart from the decked boat design, are mostly held in place by the paddler's legs, hence my calling them my "Legs Fixtures".
Some modifications will be required to each of these designs to adapt them to the particular kayak of interest, however you may find that these designs are quite easily adapted and configured to work on a wide vairety of models.
I'll leave you to explore my web site, for now, to find further information on these and other Adaptive Kayaking designs that I have created and published.
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