Introduction: Building a One Sheet Boat

Warning: Woodworking is inherently dangerous. You are using sharp tools some of them spinning at large RPM's. You need to be wearing eye protection at all times, hearing protection as needed and because you are going to be working on some very small pieces you must use a push stick. Niether I or Instructables bear any responsibility if you do something stupid, lose focus, act carelessly, or recklessly.
The same can be said about boating, you should be wearing a life vest anytime you are in a boat and always acting in a safe manner.
The town I live in has a boat building/ racing contest every year. The challenge to this contest is the materials you are allowed to use as well as the ones you are not.

The materials include:
1) 1 sheet of Plywood (any thinckness)  
2) 2 8 foot long 2X4's
3) 1 Roll of Duct tape (Essential for almost everything I build)
4) 1 Lbs of fasteners (I chose 1X6 rough thread drywall screws)

You are not allowed to use Glue, Epoxy, Chaulk, Silicone... In short NO adhesives at all.
The boats may be decorated with paint and will also be judged on theme and appearance.

I had paint laying around so my total cash outlay was less then $50
Here is a link tot he Yahoo groups that I got the plan / desgn from along with some great advice.

Step 1: Materials

1) 1 4'X 8' sheet of 1/4 inch B/C grade plywood
2) 2 8" 2x4's (As few knots and a straight as possible, Yeah, Yeah I know) If you are not entering a contest like I was you might want to  get a knot free 1x4 for the chine logs.
3) 1 Roll of Duct tape. (Once again if you are not entering a contest like I did get yourself some waterproof adhesive, chaulk and maybe some fiberglass tape and resin for the seams.)
4) 1 Lbs of fasteners, I used about 1/2 lb of 1"x6 coarse thread drywall screws. I f you can get 3/4 inch that will be great for the Chines and Gunwales  and Iwales (Pronouned gunnel and innel).
5) You will also need a scrap piece of wood 32" x12" that you will use for a removable form

Step 2: Tools

Here is a list of the tools I used:
1) Jig Saw/ portable scroll saw
2 ) Battery powered drill
3)  Belt Sander
4)  Circular saw
5) Hand plane 
6) Adjustable artist triangle
7) Drill and countersink set including #6 Drill and Phillips head bit.
8) Squares ( I used a Try Square, and a Framing square. but you can use a straight edge instead of the framing square)
9) Tape measure 
10) Clamps- as many as you can get your hands on, there is no such thing as to many clamps.
11) Disc Finish Sander
12) Back saw
Not pictured:
8'+ Straight edge
Band saw
Table saw

Step 3: Cutting the Sides and Bottom

Use the Tape measure and measure in from each of the side factory edges 12". Do it on both sides and both ends. I marked it using a sharpie so it would show up in the pictures. Next set it on top of the 2 2x4's leaveing a gap of 3-4 inches.

Set your Circular saw so that it just cuts through your ply and does not cut into your work surface.

Run it down both lines so that you have two strips 12 inches wide and 1 piece that is about 23 1/2 inches wide (You wil need to measure yours for the next step).

Step 4: Side Construction

Once the sidies are completed butt the 8" factory edges up agaisnt each other. For the Stern you want to measure in 2" and for the Bow (Stem) 3". While they are still butted together measure  down the length 48" . Use a square to mark the centerline.
Next cut out the out the stern and bow triangles. At this point I suggest marking the sides so that you end up with both sides matching when you install them.
Set them aside for now 

Step 5: Temporary Frame: Constructing

The purpose of the frame is to hold the sides in place so that you can add the Stem and Stern pieces, Chine logs, and finally the Bottom (You can also leave it in place to install the Gunwales and Thwarts as I did).
The first step is the measurement of the bottom width as I mentioned in the previous step. this is obviously the maximum width you can have. I subtracted about an extra inch to account for the (2) 1/4 inch thick sides and I wanted about a 1/4 inch over hang on both sides for margin of error.
The plan I used called for the maximun width at the top to be 32 inches, but I felt that would torture the plywood just a little to much for my taste so I reduced that by a little over an inch (Use your own judgement here).
My final dimensions ended up with the top at 30 3/4 inch, base at 22 1/2 and the height of 12 inches. There are two ways to determine the angle to cut this to on the table saw. You can either use the adjustable triangle or set it on top of the saw and line it up with the miter slot. Loosen the miter guage and slide it up to the frame and lock the angle into place. (You will want to save one of the triangles you cut to set the blade tilt for your chine logs.)
Next you want to notch all four corners. the ones at the Bottom are going to be 1" tall and 2" wide. This gives you clearance for the chine logs. The top ones are going to be about 1/2 inch wide and about 2" tall for installing the gunwales ( I didn't cut out the gunwales notches and had to remove my frame cut them out and reinstall the frame, save this step and cut them out ahead of time).
I cut mine out with a band saw but you could use a hand saw or jig saw.

Step 6: Temporary Frame: Installation

Place your frame on a work surface so that it is vertical with the bottom facing up.Grab either side. You want the Factory edge to be flush with the bottom.
Drill two holes right on the line you drew in step 4. Make sure that the holes do not go through where you are going to install the chines and gunwales. Center the line on the frame and use your electric drill to screw into place.
Repeat on the other side.
At this point to need to take a measurement for the tapers on the stem and stern post.
Bring the sides together at either end (The measurement is close enough that you  only need to do one end.
If you have a helper have them hold both pieces together. Set a piece of scrap wood on your boat as in the picture. Reach underneath and trace the angle.
I didn't have a helper so I opend up a parallel clampand bent the sides to stay in the jaws, with out putting preasure on them (see the finalk picture below).

Step 7: Construct the Stem and Stern Post

Make sure that you use a push stick for this operation.
Take on of the 2x4's and cut off a piece approximately 14 inches long.
Rip this down the center so that you have 2 pieces 1 1/2 inches square by about 14 inches long.
Set you table saw to a 45 degree angle and rip both pieces. I intentially did not have the angle come to a point (The purpose of the 45 degrees is that it gives you a square. edge to keep on the table top and rip fence)
Next I used a protractor to measure angle you created on the scrap piece from the previous step. Mine was about 40 degrees so I settled on a dimension of 20 degrees as a nice round number. 
Now you need to set your saw angle To give myself the widest base to saw with I set in on the 45 degree angle and used the adjustable triangle a seen below.
You will notice that once again I didn't want the angle to come to a perfect point. I tried to leave about 3/16ths per side as you can see in the last picture below.

Step 8: Installing the Stem and Stern Posts

Take either post and clamp it to one side of the boat. You want to have some over hang at both the top and bottom. Drill and screw this into place. Bring the other side into place and make sure that both sides are level. If you have a helper great, if not it is back to the clamps. (If you are using Adhesive apply it to each side prior to installation)

Repeat this step at the other end so that it looks like the final picture below.

Step 9: Chine Logs

Make sure you are using a push stick for this operation.
Find the 2x4 with the least knots and rip off a piece 8 ft long by about 3/4 in thick. Find the center of piece from both edges and mark a cross on it. Laying the 1 1/2 wide part on the table use the scrap triangle from step 5 and run an angled line through the center of the cross.
Set the blade angle witht he same triangle.
Place the 3/4 edge up against he saw fence and eye it up so that you will be cutting right through the line you just made. You want this to be a centered as possible to that both pieces are identical.

Step 10: Installing the Chine Logs

Take the chine logs you made in the last step.
Use your adjustable triangle to measure the angle between the the stempost and the interior side. Mark this and cut the angle with either the hand saw or the band saw.
You are going to install these with the widest part down. Clamp this piece at one end  SLOWLY and CAREFULLY work your way around, installing clamps every couple of inches. if you hear cracking, that is a bod thing and you are goiong to fast.

Some people wet these down before hand or even steam them, but if you are working with very small knots and are very careful you should not need to. The second pictures shows my clamps installed with the first chine. When you get near the end you will need to cut it to final length. Mark it with a pencil eyeing up the angle and use the hand saw to cut it to size. (If you are using Adhesive apply it to each side prior to installation)
Be careful one of my chines had a large knot and now let's just say I have a spare chine laying around for a future boat.
Some one suggested that I install the screws every two inches. This seemed like over kill to me since I knew that I was going to be installing a Gunwale on the outside.
I pre-drilled and counter sunk each screw as I went along about every 4 inches or so and installed them as I went along as well. It is a good idea to remove the clamps while you are working to see if you need additional screws.
When you are done you will see that the chine logs stick up above the sides at the ends and should be level at the frame (See picture below)
Use a handplane or sander to make these level. use the straight edge and do both sides at the same time. 

Step 11: Marking and Cutting the Bottom

Place the bottom on the sides so that one end is butted up to either the stem or stern post.  Mark the center of the end and screw the bottom to the post. Mark the end that you started with on both the post and the bottom so that you can make sure to reinstall it the same way (You can see the 'C" that I used for mine).
Move to the temporary frame and make a line across the bottom using the lines on the side as references. Drill  and screw 1-3 places here. Move to the other end and screw this to the other post. You may need to measure in from the end as there will be about a 1 foot over hang.
At this point you can trace around the outside while it is inverted or if you are feeling up to it flipping it over. It doesn't make any difference which way you do it.
Remove all the screws and you will have a perfect outline of the bottom shape.
Take your portable jig saw and begin cutting outside the line. How much outside depends on how lucky you feel. I left between 1/4 and 3/8th inch.

Step 12: Install and Sand the Bottom to Fit

(At this point if you are using adhesive apply it carfully to the Chine logs and edges of the sides)
Start at your origin hole and reinstall the placement screws trying to make sure that you get them back into the original holes so that everything lines up.
Moving around the boat install screws every 3 inches or so. Once this is done you can either use the hand plane or belt sander to make the bottom and sides flush See the second photo below 

Step 13: Gunwales and Inwales

The Gunwales serve the strengthen the sides at the the Top and Bottom, and an Inwale on the top on the inside.
To make sure that I was not going to hit any of the screws holding the Chine logs in place at each chine screw location I made a tick mark on the bottom with a pencil (You can see this in the first picture).
I cut each (6) of the Guwales and Inwales from the rest of the 8 ft 2x4. Each one should be just over 1/4 inch in thickness and 1 1/2 inch wide.
Mark the center (4 foot) of each Gunwale and Inwale.
(If you are using Adhesive apply it to each Gunnel prior to installation)
With the boat inverted (Bottom up) begin working from the center out drilling and screwing as you go. By the time you  get to the end you should have about 2-3 inches hanging over, cut this off flush to end with your hand saw.
Go back to the center and work to the other end and repeat on the other side.
Next come the top Gunwales and Inwales.
Flip the boat over so that the top is up again. You will need to trim the Inwales the same way you trimmed the Chine Logs in step #9 if they are a little short (As mine are) it doesn't really matter.
(If you are using Adhesive apply it to each Gunwale and Inwale prior to installation)
Once this trimming is done clamp the Gunwales and Inwales together at the center. I moved the clamps as I moved toward each end. My screws were to long, so as you can see in the second picture I put them in at an angle. If you are able to buy the 3/4 inch ones and you cut your Gunwales and Inwales over 1/4 inch thick you should not have the problem, The alternative is to drive them straight in and grind them off after they are all done.

Step 14: Making the Thwarts

To make sure that the boat keeps its shape you need to install to thwarts a little less than 1/3 of the distance from each end.
I measured along each side 32 inches from the stem and stern and made a tick mark (The tick mark is vissible in the first picture of step #15). Then measure across the boat at those points. Mine was about 24 inches. I then layed the thwart acorss the Beam (Top) so that  they over hang just slightlyand traced the curve, at both ends of the thwart. Cut this on the Band saw. Next turn the thwart on its edge and mark a line that goes right down the center as  in the second picture below (I made the line very dark so that it would show up in the picture). Being very careful resaw the stock on the Band saw, It will end up being about 5/8ths of an inch thick. It is much easier to sand this before you install them.

Step 15: Installing the Thwarts

At this point you want to put a clamp at each of the tick marks you made for the thwarts. make sure they extend about 3/4 of an inch below the Inwales as shown in the first picture. You may have to twist the thwarts a bit to  get them installed so be careful.
(If you are using Adhesive apply it to each end prior to installation)
Once they are in place go to the outside of the boat and drill 3 holes about  5/16ths of an inch from the Gunwale, drill and countersink. I installed two screws and them removed the clamp to install the third. 
At this point you can remove the temporary frame.
You can see the installed Thwarts in the third picture adn also several strips that I installed to cover up the holes made from the Frame installation

Step 16: Painting

Now is the time to let your imagination run wild you need to come up with a great name and a paint job to match it. I coated all the seams with several coats of latex paint to fill in gaps and seal up any areas that might have leaks. 

Step 17: Test Her Out

Took her to the quarry this morning and she works like a dream. No leaking at all. I do have to repaint the bottom because i didn't prep the previous coat enough. The Kayak Paddle works great and she tracks pretty well for such a small boat.