Introduction: PVC Pipe + Tarp Kayak
In the field of outdoor activities, kayaking has taken ahold of society due to its ease of introduction, physical accessibility, and versatility. In particular, the act of kayaking is accessible to all types of people, potentially even those who are wheelchair-bound, as seen in the article by Carsten Froehlich, "Recreational Rehabilitation". The main limiting factor of kayaking when it comes to reaching all people, however, is price. A lower end kayak will cost around $300, which is a huge sum to a child or low-income adult. This project aims to fix that, allowing for a fully useable kayak for a price tag of <$100 and a few days of hard work.
Step 1: Material Procurement
1. A skeleton (frame):
This is a strong, flexible material that can easily be attached to itself in a variety of ways in order to make stringers and ribs. For this project, I am using ~70 feet of 3/4" Sch. 40 PVC pipe in 10 foot segments. I also use some 3/4" couplers.
2. Flooring and seating:
This is a stiffer, flatter material that will be used to enter and exit the boat, while also acting as a seat. I am using a couple short segments of 1"x4" planks.
3. Fastening materials:
This is self explanatory. For this project I will be using simple wood screws and strong cordage (for end-to-end joining of pipe).
This is a flexible, waterproof skin that will be stretched taut around the frame and fastened in order to create a finished boat. I will be using a heavy duty tarp (10'x12').
-Heat gun for making sharp bends in the PVC in a safe and controlled manner. Can be substituted with a stovetop if necessary.
-Pipe Saw/Cutter for cutting the pipe to length. A measuring and marking tool will have to be used first.
-Drill/Driver for first putting holes in the PVC and then fastening the pieces together.
As you can see, the cost of materials is actually quite low. In the article "The Allure of Kayaking," by John McGonigle, the kayaks that people normally get to enter the hobby range in prices upwards of $300. I also observed this in person when I went to my local sporting good store, Canfield's. This means that I ended up paying around one-fifteenth of the cost I would've had to pay in order to get an entry-level kayak and also got to do some fun DIY building.
Step 2: Frame Construction: Stringers
I read 2011 article titled "Gone Kayak Fishing" which outlined the different types of kayaks and accessories for them. It helped me to decide on the dimensions of the craft so that it could perform well in many different potential kayak activities.
First, take two 10' segments and tie them together at one end with your cord.
I went with a square knot to finish it up, which holds together well when using paracord. If you're using something slippery (polypropylene) I would recommend putting a lot of extra loops in. This knot will be under pressure constantly once the kayak is finished, and absolutely can't come undone.
The segments can then be tied together at the other end.
Take another two 10' segments and shorten them each by 8 inches. These pieces are being shortened so that when they are attached to the longer ones, a curve will be formed. If you have decided to use make a shorter kayak, you may want to change this trim to something more proportional to your overall length in order to preserve the overall curve.
Before heading on to the next step, I recommend marking the center-point on each segment. (60" from the end on the longer pair, and 56" from the end on the shorter pair.)
Step 3: Frame Construction: Ribs
Take two 68" segments of PVS and mark them at 13" and 21" in from each side.
These marks are where the pipe will be bent 90 degrees.
Soften them up with your heat gun (or in this case, an electric stovetop) but avoid burning them. PVC that has been burned becomes very brittle and could potentially lead to injury when stress is put on it.
Once you have all the bend points softened and bent, you will have two 8" x 26" PVC rectangles which can be finished with a coupler.
Step 4: Frame Construction: Finishing
Your rectangles will be the ribs of the kayak, and should be screwed onto the stringers 20" from the center. (This is why it is important that you mark center on your stringers.)
Once all 8 mounting points are secure, the ends of the Stringers can be lashed to each other, forming a 4-point cluster. Pulling the upper set to the lower set will take some strength (due to their mismatched lengths) but creates the asymmetrical curve that is important to the application of a kayak.
At this stage, I decided the kayak should be more secure and have a more stable shape, so I took another 10' segment and attached it as a "keel". This was done by first tying it to the four-point cluster on one side. I then bent it over to the other side and cut it to length. After tying this piece on both sides, I then added lash points where it contacted the ribs in order to add stability.
For the next step, I cut two 1x4's to 39 and 1/2" and screwed them to the ribs 3" apart. You may want to vary this distance for your comfort, as it will be the seat (at least temporarily).
I conducted an interview with the engineering teacher at my school, and received advice for various aspects of this project. One helpful tip he gave me was to buy simple plastic boat seats, so the planks also function as the mount type for a seat of this type.
Step 5: Skin Attachment
For this step, you'll want to lay the tarp down with the kayak on top of it to get an idea of how it's going to be stretched around it. This can be done in a variety of ways, some of which would work out better than the way I did, but this is the only way I can recommend. After all, this method does end up slightly ugly.
Fold the tarp onto the kayak at each tip and attach it in a way that holds the tarp taut but can be easily removed. Next, I took the two "wings" and folded them over the tip to get an idea of where they could meet and be tied together. I drew a line with a permanent marker, and cut across with scissors. When you have the two ends that meet in the middle, transplant the grommets from the original edge to the new one with duct tape. Now the two parts can simply be "stitched" together with cord.