How to Build a Cardboard Kayak for Less Than 40$ (Updated With Template)

I decided to build a kayak out of cardboard using a plywood lamination technique in order to make the cardboard strong enough. Basically cardboard has a grain like wood, so you just change the grain direction with each layer, like they do when they make plywood, and viola, you have "plyboard".

As a cautionary note to those of you ambitious enough to try this yourself, know that it takes ALOT of time, effort, and planing. I managed to go from model and blueprint to full kayak in just 4 days, but know that I lost ALOT of sleep staying up late to laminate layers of cardboard layers, and there were several features that I simply did not have enough time to construct. I spent a few weeks in preparation scrounging around cardboard dumpsters looking for large, pristine (pristine is KEY as we learned) double layer (two layers thick) cardboard. You need ALOT of cardboard, the sheet used to make my kayak measured 6 ft wide by 10 feet long. With four layers to it, thats 240 square feet of cardboard!

Also, you need a large flat space on which to construct your plyboard.

Anyways, the great thing about making your own kayak is that you can make it to any specifications you want, and add any feature you want as well. My brother for instance, said he would have made a flat backed kayak so that he could put a trolling motor on his..... go nuts!

Also, you really REALLY need at least two people to build one of these, three is much better/easier. I was lucky enough to have the help of my Dad, my best friend, and my brother at times....

Enough disclaimer, lets get into the build process!

You will need:

1 gallon of waterproof wood glue - 16-18$ @ Home Depot
paint roller - dollar store is fine, as cheap as you can get it, i got a nice combo pack at family dollar for 8$
paint tray - same as above
paint tray liners (3 or 4 is best) -same as above
good utility knife and lots of fresh sharp blades
skill saw with a fine toothed blade
140 or so bottles of beer, water, or any other small, relatively light weights
aprox. 300 sq feet of pressure sensitive adhesive backed vinyl (glorified contact paper)
masking tape
chalk line

optional;
Drywall square

The vinyl item is a tricky one, you MAY be able to find it by finding a local print shop that specializes in truck or vehicle wraps, and asking them if they have any bad, damaged or miss-printed rolls. It is just the waterproofing layer, so it just needs to be free of holes...

Also, i tested an alternative method of waterproofing, which is much more readily available. Helmsman Spar Polyurethane, make sure its for exterior and waterproof, i almost bought the interior stuff by mistake. Anyways, a couple LIBERAL coats of that (two is the absolute minimum, 3 or 4 is MUCH better) would work just fine. As i was pressured for time (i procrastinate, what can i say?) i opted for the vinyl, and as my father an I both work at a company that manufactures and designs billboard printers, coming by a few used rolls through a little dumpster diving was a piece of cake.

Oh yeah, How could i forget, you need CARDBOARD, AND LOTS OF IT!

This is technically an optional step, but one that is highly recommended. Making a to scale model of your final kayak will help you to see any potential design flaws before you get to the real thing. It also helps you to visualize the shape, and better understand the hydrodynamics of the hull.

I've got a lot of people asking me for a drawing of the plan that I used. I would caution that if you are planing on using paint, polyurethane, or any other method of waterproofing your kayak, you should shiplap the joints. This basically means leave about 2-4 inches beyond what you need and then glue that flap on top of the other side. Overlap your seams, basically.

UPDATE: Okay, i finaly got a PDF version of the template done up, and it should be attached to this step. It's diemensioned and has fold lines with the degree the fold requires indicated. Ovbiously, you don't need to bend the folds to excatly 45.12 degress, just if you are going to make this kayak out of say, sheet metal, it's important to have that sort of acuracy. Sorry it took me so long to get the template up, I had to learn how to use the Sheet metal function in SolidWorks, and then model it.... time consuming to say the least. Anyways, would love to hear if anyone ends up building it.

If your like me, and your only option is a nice hardwood floor, do yourself a favor and cover it up with whatever it takes, just in the event that a glue spill should occur...... it also helps if whatever you put down you can make marks on, as it will help with laying out the large sheet you are about to begin constructing.

We found the trick to getting everything to line up nice, was to use a drywall square (which is optional, but highly recommended) so that each piece was cut square and the seams lined up nice and flush with each other. Also, you want to cut any seams out of the cardboard, so that your sheet is made of only nice, pristine squares of cardboard. We figured the sizes out by just marking out a 6 by 10 rectangle on the floor and then putting our biggest piece down first, and marking the next one by lining it up and marking where the lines of the rectangle on the floor met the cardboard piece we were trimming. you could take the time to measure, but this method worked just fine.

MAKE SURE THE GRAIN IN THE LAYER IS ALL GOING THE SAME WAY! This is crucial, the entire design hinges upon this one element. Cardboard, has a grain direction to it, and each layer must have all the sheets that make it up orientated so that it is all going in the same direction, with each layer having the grain rotated 90 degrees from the one below it.

For a visual break down of the grain orientation of each layer, look at the last few photos. please understand that I did the grain visual break down on a model of each layer, and that in reality, each of your layers will be 6ft by 10ft if you follow my plan to the letter....

Put down all the cardboard you just cut, and masking tape it together. You don't need to go crazy with the tape, just enough to keep the sheets together. Once you have your first layer laid out, cut enough cardboard for another layer, but this time with all the grain in the cardboard going the other direction (perpendicular to the layer below it) and lay that one out on top of the first one, just to make sure it fits.

So take your glue, and dump a liberal amount into your paint tray liner sitting in your paint tray. Take your roller and dip it in the glue. We learned (the hard way) that it is much better to put too much glue on than too little. Trust me on this one, it is a royal pain to have to go back and repair layers when they de-laminate because you didn't have enough glue down.

Once you've got your glue on, start sticking on your sheets of cardboard. we found it was helpful to layout the layer first, make a bunch of reference marks, in terms of how each should line up with the other, and then laminate. That way when you go to put down a piece of cardboard, you can look at the one you put down right before it and go, oh i see, that one lines up with this line, so it must go here. Very simple trick, yet saves alot of time and confusion. Press the cardboard firmly into place, but not too hard, as we don't want to dent the sheet and ruin it's structural integrity.

Weight your cardboard with lots of small, "light" weights. We want each weight to be relatively light so that it does not dent the cardboard, yet heavy enough so that it weighs the cardboard down. We brew our own beer, so we had alot of bottles on hand, so my brother filled them with water, caped them (because a spill would mean the end of our kayak at this point) and we laid them on the sheet. We found that the seams, where two sheets of cardboard would meet, were the most troublesome spots. They seemed to want to warp up for some reason, so this is where we put most of the bottles. If you don't have 140 bottles kicking around, or a capper, just go to the local dump or transfer or recycling center and get alot of soda bottles, and use those instead. Also, you could use books, placed in bags, plastic or paper, does not matter, just helps keep the books from getting glue on them. Or fill sandwich bags with sand, any small weights that you can think of, that you have a lot of.

Leave each layer to dry overnight, and then cut a new layer (with the grain going 90degrees different from the previous layer) and repeat until you have a sheet that is four layers thick. since i highly recommend using double layered cardboard, it's technically 8 layers thick, but whatever. the point is make it beefy, you don't want to be putting your foot through the bottom of your kayak cause you were lazy and only did a few layers......

Next, lay out your kayak on your sheet of plyboard that you just finished, and use a chalk line to snap the lines. Then using your skill saw and a fine toothed blade, cut the cardboard to all but the last layer, and bevel the cut so that when you bend it up, the two surfaces you just cut, come together so you can glue them. After that, apply the contact paper to the entire surface, making sure to get all the edges corners and nooks and crannies. this step is crucial, if not done properly your kayak will soak up water like the big cardboard sponge that it is, and you will be the proud but not so dry owner of the first ever cardboard submarine! Also, it is much easyier to waterproof the kayak while it is still in a flat sheet form, rather than all folded up.

waterproofing can also be done by applying SEVERAL (as in more than one) liberal coats of helmsman spar polyurethane.

Fold it together, and laminate the seams. Again make sure they are as water tight as you can get them as a leak will spell certain doom. Make sure to do the inside as well as the outside, if you flip over, the inside needs to be just as waterproof as the outside.

If your like me, and used white vinyl to waterproof, go nuts and decorate it. Also the nice part about making it all out of cardboard, is that it is super light weight. I could lift it with only one hand. The drawback to the vinyl was that it was kinda hard to cary, as the surface was so slippery, but that could easily be fixed with a couple handles. My kayak design had a shallow, or flatter hull, which made it much more agile and maneuverable, but it also meant that a slight breeze will blow me sideways. A sharper hull design, would act more like a centerboard, and help to give kayak stability. Change it up, go nuts, deign your own! They're super cheap and relatively easy to build.

The kayak weighs only 35lbs. I measured by standing on a scale, then holding the kayak, and then subtracting my weight, so it may be off by a few pounds, but it is still super light.