Chugger


Building Instructions for Chugger, a Minimal Motor Cabin Cruiser for Two People for a weekend or so.


Note** The instructions assume a 12’ version is to be made. For longer boats, additional supplies will be needed and of  thicker dimensions. For lengthened versions, versions with narrowed bows and any other modifications, additional info will be provided in a different document.

Note*** Please read these instructions thoroughly at least twice before buying anything and again before starting to build. Know what you want to do BEFORE you do it. Measure twice, then once more, before cutting. If you have questions, contact me at numbaoneman@boatbuilding.com


Bill of Materials:  (Not all inclusive but a good start.  Better materials will give better results and last longer.

-2 Sheets of 3/8 ply for bottom. 
-4 Sheets of ¼”  ply for sides (3/8” optional). Leftovers are used elsewhere.
-1 Sheet of ¾” ply for transoms.
-2” thick Styrofoam sheets or 2 part liquid foam flotation.
-Start with 25 1x2” and 3 2x2”s fir or pine furring strips or 15 1x2” and 10 2x2”s for 
heavier framing.
-1 1”x3”x 4’ piece of clear oak (to attach to the bottom of the front transom)
-stainless or galvanized #10 screws. ¾” (300), 1 ¼” (200), 2+” (100) 
-1 –1.5 gallons of epoxy for glassing the chines (and the bottom if desired)
-Thickening agent (wood flour, cab-o-sil, silica, milled glass, powdered limestone)
-1 roll (50yds) of 4” fiberglass tape or cloth cut on the bias.
-6-8 yards of 50” 4-8 oz FG cloth (if glassing the bottom).
-Sandpaper, mixing sticks, plastic containers, vinegar, acetone, cheap paintbrushes, paint 
rollers, plastic or vinyl gloves, and cheap, notched spreader.
-Primer and exterior latex or oil based paint, or if you feel rich, two part epoxy paint.
-3/16” Plexiglas for the windows. (wait until you need it to get it, unless it goes on sale).
-You may wish to substitute nice moldings in better woods for the false sheer, finishing 
them to show off the wood. All ply should have exterior grade glue. Any of the 
woods may be upgraded to suit your needs, desires and pocket book. 

I built this boat for less than $150.00 (US)(no windows) using luaun underlayment and  B/C exterior ply and pine/fir 1x2s, 1x4s and 1x6s, I also used some 2x2s I had laying around. The ¾” ply was also luaun and the paint was exterior latex(white) and exterior oil (red).  I framed light and the boat is sturdy enough, but  in most places 2x2s may be substituted if one feels the need for added security. For longer boats, 2x2s may be the better option for more of the framing.


Caution: When using screws, always pre drill the holes, to prevent splitting of the wood. Countersinking is recommended too.


Building the boat:

The Rear Transom: 
		Cut out the boards that will make the transoms. The first piece is 47 ½” ( assuming 1/4” for the sides) by 23 5/8” (3/8”for the bottom). The rear transom doubler will be cut to fit between the bottom panel and the bottom of your motor cutout. Leave this until you determine what shaft length your motor will be.

The Front Transom:
		Cut the front transom out, 47 ½”x 28”,  leaving enough on the bottom to trim down to match the angle of the curve of the sides. Glue and screw the  second piece of wood (the oak) to the bottom of the transom, across the whole width. Cut the bevel after gluing so as to have the two match. This will help in attaching the bottom. Wait to cut the bevel until you have determined the angle from the side panels, after laying out the curve.
 

The Side, Roof, Deck and Front window panels:
		The Side Panels: Start by laying out the front curve. Determine which edge of the ply will be the bottom and which end is the front. On your sheet of ply, measure up 9” from the bottom, on the front edge, and mark. From the front edge, measure 36” back and mark. Connecting these points with a flexible batten will determine the curve. Try to have the belly of the curve just to the front of the center of the curve, as this will ease the transition to the flat section of the bottom. Remember: you will have to curve 1x2 stock and 3/8” ply to match this curve too, so make it as gentle as you can while still getting an easy transition  into the flat. If the transition is too abrupt, the chine log will not curve to it and you will have a hump at this point. This will also ease the angle at which the water meets the bottom and not plow furrows in the water. Now that the curve is drawn, measure down from the top of the sheet 1 ft and mark on the front edge. This is where the front of the deck will be.   Measure 2 ft back and 1 ft  down from the top of the sheet and this is where the front of the cabin meets the deck. Connect the points.  Measure 6” back and mark the edge of the ply. This is the front of the roof. Connect the points with a straight line. The lines should resemble the front of Chugger in the drawings. The rest of the sheet length is left straight. The final 3” of the sheet needs to be cut off, to butt the front and rear panels together and have the cabin length come out right.. The 3 “ will be replaced by 3” of the rear panel. Clamp the two sheets that make the front panels and cut them out. 
	To layout the rear panels, measure 3” from the front edge and mark the top edge of the ply. Measure 4ft from this and mark. On the bottom edge, measure from the front 4‘ 3”  and mark. Connect the two marks. Measure up 24” from the bottom and draw a line along the length of the sheet. Now we have to get the curve shown between the cabin and the cockpit. The radius is 24”and should connect the top mark at 3” with the line drawn across the  center of the ply. You can use the old string , pencil and nail method or make a Redneck Compass, as shown on the Being Built pages on my web site. Once you have the curve and it looks like the drawings, clamp the two sheets together and cut them out. When marking and cutting the sheets, face the good side in, so that they will not be damaged by the cutting. Once you have the front and rear side panels cut out. It is time to……
	
Join the panels:
	To join the panels, Butt joints, with 1x6” butt blocks and fiberglass tape or cloth will be used. The 1x6”s serve double duty as butt blocks and framing. Glue and screw or clamp the front and rear panels together, using the butt block on the inside and epoxy or PL Premium construction adhesive. Make sure the edge of  the butt block is back ¼” from the edge of the top of the curve (for the bulkhead ply later on). If screwing, countersink a little and fill the holes. Leave ¾” at the top and ¾” at the bottom of the 1x6” to allow for the chine logs and upper framing. If framing with 2x2s, leave 1 ½” at the top. Regardless of the choice of framing, once the butt blocks are in place and dried/cured, Glass the outside of the joint for strength and waterproofing. Once both the sides are done and cured, it is time to put some framing on.
	The Roof, Deck and Front panels: The roof is the full sheet width, and cut to the length of the cabin roof measured off the side panels plus enough to cover the front window panel edge. The deck and front window panels are the same width. Measure the deck panel to include the bevel where it meets the front of the cabin, and cut to the bevel so it fits flush. When measuring the front window panel, be sure to take the thickness of the front deck into account as the window panel will be resting on top of it. 

 
Framing and Chine Logs: 
	The chine logs are of clear 1x2’ stock and run the length of the boat bottom. Using epoxy or PL and screws attach the chine log to the inside of the side panels. Start from the front and get some help. Use clamps. Pre-drill each hole, especially near the ends of the 1x2s so that they don’t split. If they do, glue and clamp the split together. Harder/better wood  helps. The 1x2s are attached edge on, giving the bottom panel the 1 ½” width to screw to. It can be done, look at the pictures on the site. I did it without help, just a few bar clamps. This is probably the hardest part of the whole build. The rest of the framing is a breeze after this.	Once the chine logs are on, the rest of the framing goes on with glue and weights or screws. 1x2 or 2x2 stock is used to frame out the bunks on the side panels. The top of the bunk framing is parallel with the straight bottom and 1 ft up. The bunks are to be 78” long, with the rearward 3 ft divided by a knee hole, to provide some sitting room. Storage is available in this area, while the front section is to be used for flotation, and maybe more storage, if desired. Frame the outline of the bunks on each of the panels. See drawings for details. Leave space at the front for the transom thickness. 
	Before framing continues, take the time to cut out the window holes. Measure 6” back from the front edge of the roof and 2 ½” down. Mark this point and draw a rectangle, 1’ x 4’, parallel with the roof line back from this point. Cut out the window openings. It is a lot easier to do it now than after the other framing is in place.

	To frame the deck and cabin, use 1x2 or 2x2s and run along the edges, up to ¼” from the edge of the curve. Glue and screw from the outside in or clamp the 1x2s on edge, just like the chine logs.  With the cabin edge framing done, the bunks framed out and the window opening cut out, we need to frame the window openings. Use a miter saw or box and frame the outside of the window, overlapping the opening by ¼” to 3/8”. Glue and clamp or screw.  Mark and install the bottom piece of framing on the inside, make and dry fit the other framing pieces but remove them and set aside until the boat is painted. Once the windows are done, install the front and middle side stiffeners. These are 1x4 pieces and run from the upper framing (bottom of window or roof framing) to within (the thickness of ply you plan on using on the bunks) + 1/16”. What I did, is take a piece of scrap of the same thickness and laid it on the bunk framing and measured to the upper framing. When the stiffener is cut it should mate with the upper framing and you should be able to insert and remove the scrap piece from between the bunk framing and the stiffener. Please view web page for a picture of this. One stiffener is installed just in front of the window opening, leaving sufficient room for the window framing, and the other is installed running from the center of the window, down to the proper distance above the bunk framing. If you wish, an additional run of 1x6” can continue from where the rear shear piece ends at the butt block, forward to the front transom, though it isn’t needed on the 12’ version . The final bit of work on the side panels for now, is to install the false shear. Getting help with this is a good idea. You will need to start from the front point and work your way back, using the length of the wood as leverage to bend it. To do it properly, you will need the help of two others. One will be holding the side up and drilling and screwing the piece on from the inside, the other will be bending the wood. You need to be in a position where you can direct the bending to the right shape.  The first 2 screws need to be no more than 3” apart, and the rest are positioned as needed. To simplify matters, 2 pieces of 3/4x3/4 square molding could be used, making the bending easier.  This is up to you. Either way, the wood will need to be smeared with glue, and bent and screwed into position. ¾” screws are perfect for the job, the smaller the # size, the better pre-drilling always. Bring the curve down so that it runs into the straight shear right where the curve straightens out and run it all the way back to the rear corner. Don’t put a screw right at the corner though, as the transom goes there, clamp it instead. Once you have one side done, make careful measurements from the bottom of the boat to the bottom of the shear piece at 3” intervals along the length of the curve. Transfer those measurements to the other side panel and bend the shear piece to match. We then need to install the inside shear brace/frame. This is made of 1x6 material and extends from the rear transom, along the edge of the cockpit shear and continues on to mate with the side panel butt block. This should complete the framing of the side pieces, with the exception of the remaining window framing.
	Next we proceed to framing the roof and front deck pieces.  We want the framing to support the panels, but not be too heavy. I recommend 1x2 pieces, framing the outline of the panels. We want the framing to fit snugly to and between the framing of the side pieces so careful measuring and placement is needed. The front piece of the framing on the roof panel will need to be beveled to match the angle of the front window panel, and flush with the edge of the ply. The rear frame piece should be 1” from the rear edge of the roof ply. This will eliminate some of the extra work I had to do later. The rest of the framing will be inset so as to clear the framing of the side panels. A couple of cross pieces are then installed to stiffen the middle of the span. The deck is framed in a similar manner, with the front frame piece just touching the inside of the front transom, and the rear piece flush with the edge of the ply. The sides are to mate with the side panel framing. Put one piece of framing in the middle of the panel, in the longest direction. The window panel will need to have the window opening cut out before framing begins. You will need to leave room for the window framing material when determining the amount of inset for the window dimensions. For example: 1x2 framing on the cabin roof will require ¾” clearance + the amount of framing overlapping the edge of the cutout,  say 1 1/8”. So the window needs to leave at least 1 7/8” from the edge of the ply to the edge of the cutout of the window. For good measure we say 2”, so the max window height can be 8” centered, for the opening. Lets make the width 42”centered, and mark and cut. If you framed the roof heavier, you will need to adjust the height and maybe the width of the opening. Frame the outside of the window the same as the side panels. Make and fit the inside framing, but don’t install it yet. Wait to install the window material until after painting the boat and framing.

Assembling the boat 
	Once all the pieces are completed, it is time to assemble the boat. Cut some 1x2” braces to 47 ½” long and drill and screw them to the inside of the chine logs and upper side panel framing. This will put the side panels the correct distance apart and let them stand so the other panels can be fit in place. When the panels are tacked in place, glue and clamp or screw the transoms in place. Use plenty of glue or thickened epoxy so as to have a strong bond. If using epoxy, it would pay to soak the edges of the transoms with unthickened epoxy because the end grain will absorb a lot of epoxy and may dry out the joint. You can use pipe clamps or screw into the edge of the ply, using long screws, 2” or longer. Pre-drill your holes and make sure they go straight into the edge, not at an angle. The screws will not be providing more than 20 % of the fastening power once the glue has dried/cured. Once the transoms are attached, square up the boat by measuring from opposing corners and adjusting so that they match. Next we put on the roof, front deck and lastly the window panel. Using ¾” screws and glue on all mating surfaces, screw the top panel ply to the side panel framing, making sure the edges are flush. Then take long screws, up to 3”, drill and screw through the side panel ply, framing and into the top panel framing. Be careful aim for the middle of the thinnest pieces so as not to come out the side of any of the framing. At this point, the boat should be square and relatively stiff, at least enough to turn over. Flip the boat over and square it up again, as best you can. It should be quite square already. To put the bottom on, we use a full sheet of ply. Glue and screw the front of the ply to the front transom and brace, and let the sheet sag over the boat. Apply glue to the chine logs and begin screwing the ply down. It goes better if there are two of you, so as to screw it down evenly. Be very careful in ensuring that the edges of  the plies are flush and square. We are assuming that the ply sheet was checked for square already. You may need to install additional framing between the chine logs to aid in pulling the ply flat in the curve. I would recommend 2x2s notched to fit over the 1x2 chine logs from the inside of the boat. Two should be sufficient, if placed equidistant along the length of the curve. This is optional and I made do without. Attach a butt block to the inside of the bottom edge and test fit the rear piece. Cut to length, glue and screw to the block, chines and transom. While the boat is upside down, now would be a good time to round over the chines and tape them. Round over and tape the side-transom joints while you are at it. Start by filling all the screw holes (you did countersink the heads a little, didn’t you?) and sanding smooth and level. If you wish to remove all the screws and fill, now is the time, but it’s easier to bury them in epoxy. Round over the chines, making a smooth curve. The bigger the radius (within reason), the better the glass tape or cloth will lay and the smoother the joint will be. Tape the entire length, from back to front. This way all overlaps will face the rear. Put a second/third coat of epoxy on while the first/second is still tacky to get the best bond. If glassing the entire bottom, allow the chines to cure, grind the edges of the glass smooth, scuff the rest of the epoxy and glass the bottom. This is the prettiest method, but you can glass right over the sticky chines and get it done without the sanding. You may end up with some bubbles/white spots along the edge of the chine tape though. If you are just taping the chines, you may wish to resin the entire bottom for waterproofing, or simply go with 2-3 coats of primer and paint. Both have proven to be almost equally waterproof. Once you have completed taping/glassing the bottom, Glue and screw the bottom strakes on. Make sure to offset the joints between the first layer and the second layer. You will have to use the 1x2 stock in order to be able to curve it properly. You may wish to fillet along the joints to ensure a good seal. Fill the screw holes and sand smooth. Put a coat of epoxy on if you wish. I would pick up some 1/8” x 1” x 8’ strips of aluminum and screw these to the strakes after the have been painted. These will protect the wood from being destroyed by dragging over rough stuff.  Turn the boat back over and we can start with the rest of the framing.

Bunk and Cabin framing: 
	Finishing off the framing is the last of the structural stuff. We need to build an arched bulkhead to add stiffness to the rear of the cabin and provide the illusion of separation between the cabin and the cockpit. We need to frame in the bunks too, and we will do these first so we can get the bunk surface in without having to fight the bulkhead (I did it backwards, what a pain!) To see what the framing looks like, please look at the pictures on the web site. I used a mix of 1x2 and 2x2s for lightness and strength. All the 1x2 were placed with the 2” part supporting the anticipated weight. You will need  at least 2 full width cross pieces plus a cleat attached to the front transom for the front portion of the bunk. Wall off the partition between the front half of the bunk and the rear half, seal it well and fill with foam flotation for safety. You could leave a portion open for storage, accessible via a sealed hatch in the bunk surface, but how much storage can you need for a couple of days? The rear of the bunks/seating area provides plenty of under seat storage, plus cabinets/cubbies can be hung below the front deck, for additional storage. There needs to be at least 12” of space between the seat parts, for knees and feet. Wider is OK, but narrower isn’t. Make sure that you leave an overlap in the framing, so the center filler piece has something to rest on. If someone comes up with a way to use this piece as a table, I would love to hear about it. The framing is cut to fit and should resemble the pictures on the site and the attached drawings. Measure and cut your bunk surface and install. You will have to bow the piece upwards in the middle (width wise) so it can slip into the slots you left in the framing on the side panels.
	To make the cabin bulkhead, 2 1x6 pieces need to be cut to fit along the edge of the cabin sides, coming to within ¼” of the cabin roof edge, and in contact with the roof. Glue, drill and screw the pieces from the sides, bottom and top. Fill in the space along the edge of the roof with a 1x2 piece, ¼” from the edge. Measure and cut a piece of ¼” ply in the shape of a squared arch, so that the edges are flush with the 1x framing and it fits under the roof ply. To mark the curves in the corners, use something round, like a coffee can, or lid or something of the sort and join the lines marked for the top and sides. Once you glue and clamp or screw this to the 1x framing the whole thing turns rock solid. Make sure your sides and corners are perfectly square and the cabin will be perfectly square. You may wish to do the inside the same way and fill the rounded gaps with solid wood for a professional look, up to you. Fit and finish of the boat depends on accuracy, patience, skill to a degree and ingenuity. Epoxy putty and a good sander can take care of a lot of the oopses. 
	Measure the shaft of  your motor, and mark and cut the transom cutout so that the anti-cavitation plate is about 1” below the bottom of the boat. Cut and install the transom doubler so that it is the same height as the lowest part of the transom, glue and screw to the transom. Add a couple of sacrifice pieces of ¼” ply so the motor doesn’t crush the transom ply. Screw these on but don’t glue, so you can replace them. A 12”x12” watertight box needs to be built at the bottom of the transom for flotation. You can fill it with foam or use it for “stuff” but it is required by the USCG (the flotation, not the box itself), to help support the motor in case of swamping. Holes will need to be drilled/cut through the flotation box bulkhead and the transom for a drain. The best way to do this for the round hole in the transom is to drill an oversized hole, fill it with thickened epoxy and re-drill to the required size (1”). This way, absolutely no water can get into the edge of the transom plywood. The holes in the box’s bulkhead can be a semicircle, with a half of PVC pipe running through the flotation box interior to the hole in the transom. Screw the pipe section onto the bottom and seal with PL Masonry caulk around the bulkhead, the transom and to the bottom. This must be done after sealing the inside of the box and before putting the top on. Make sure to seal the edge of the plywood around the pipe section. Water WILL get into the cockpit (rain, climbing in and out, etc) and you need a way of draining it out when you pull the boat out of the water, unless you want to stand the boat on end and drain it that way. 
To hold the poles (closet rod) for the canopy, knees are installed in the corners by the rear transom (they also brace the transom, double duty). These are triangular pieces that have a hole cut in them for the pole to slide through. A piece of PVC pipe will have to installed in the flotation box, directly under the knee, to be the socket for the pole. This will allow the whole shebang to be removed. Pieces of  PVC pipe will need to be installed in the corners of the cabin bulkhead for the front poles. You can have just a canopy for sun or have sides that roll down to enclose the cockpit for rainy weather/privacy/additional sleeping space for kids. Use 1x2s to frame the top part of the canopy and use removable pegs to fasten to the poles.

	Sanding and Waterproofing:
	Sand the boat to smooth the tape ridges, any ply tear out from cutting and to remove the surface wood hairs that show up when you paint. You may wish to tape all the joints around the cabin, this is up to you. The glue you used on the joints, along with the primer and paint should seal out any leaks from rain.  Sand between coats of primer and paint, for a really nice, smooth finish. To waterproof the boat, 2-3 coats of primer, and 2-3 coats of Latex paint are sufficient. Adding a coat of epoxy (If you are going to do this, you might as well tape the joints too) to the wood will reduce the # of coats of primer and paint needed. Sanding between coats will give a nice finish. Use Semi-Gloss or Satin for down playing imperfections or Gloss if you don’t care or are really good.  Depending upon the type of ply used, checking will occur regardless of resin or paint. The remedy is to repaint or glass all surfaces exposed to sun/weather (in other words… the whole boat). Checking is where the grain of the wood separates due to exposure to the UV and temperature/humidity changes. This cracks the surface of the paint and allows moisture/water to penetrate the wood A light sanding and a coat of paint is usually good for a year or so if the boat is covered when not in use, again, unless the whole boat is coated with a layer of glass cloth. If glassed, the finish should last  2-3  years with proper care and touch ups of any scrapes. Paint the bottom of the boat first, then turn it over on something soft and paint the rest. Follow the paint manufacturer’s recommendations as to how long to let the paint cure. Dry does not mean that the paint is hard or cured properly. The boat should sit for at least 1 week somewhere slightly cool and very dry and out of the sun, to let the paint cure, before subjecting it to any rough treatment (dragging, scraping etc). Examine the paint before putting the boat in the water, as the drying paint may have split or cracked and may need a touch up. Don’ forget to paint the window framing  and install the windows after the paint has dried. Use a bead of silicone caulk to bed the Plexiglas into the opening and finish framing with previously painted framing.


Finishing Touches:
	Installing shelving for a Coleman stove, installing cabinets and cubbies, the porta-potty and rigging up a sink are all finishing touches and entirely up to you., as is the type and amount of cushioning for the bunks. For the sink, I would say that a container of water on the roof, with a hose running down to a little bar sink, and a 5 gallon bucket underneath would be the best solution. For the bunks, look to find cushions for RVs as they may well be adapted to fit Chugger. The shelf for the stove should fold, so as to be out of the way. I see the Porta-Potty stored under the stove shelf. Hang a curtain on the cabin bulkhead opening and away you go. I also thought of installing an interior light, like a courtesy light from a car, in the center of the ceiling, for reading and such.  A good sized cooler serves as an additional seat, foot rest and food and beverage container. I had planned on using resin chairs for seating in the cockpit.



Please feel free to email any comments or suggestions for improvement to these plans and instructions. Let me know if I missed anything.  Any and all suggestions may be incorporated into future iterations of these plans or an add on FAQ document.

Steve Lewis	
numbaoneman@boatbuilding.com
3818 3rd Ave.
Sioux City, IA. 51106 







All plans, instructions and drawings © Steven Lewis, Lewis Boat Works. 2001, 2002