DIY Cabin for the Flapdoodle Dinghy
(Cabindoodle, or Flapcruiser?)
For those interested in Microcruising   

As I was designing this accessory, I wanted some idea of just how roomy it would be inside. Searching the 'net I found it is roughly what you would have in a surplus Army two man pup tent.

I know. This is probably far more than anyone but me would want to go through just to dinghy cruise. At the other end of the spectrum, there is the boom tent. If you wish to go that route, Google for "dinghy boom tent" and see what others have done. I accidentally found this site that has an incredible collection of DIY outdoor gear. Look at the section in the left hand menu shelters. It has a wealth of information on techniques and materials. Your needs may be somewhere between what I have done, and a boom shelter. Feel free to use what has been presented here. Maybe you would like to use only the parts that mate with the gunwale, and fabric for the rest of it.

One reason I went this way was so I could experiment with a wing sail, which does not have a boom.

Design considerations.  Weeks were spent agonizing over the height. I wanted it as low as possible to present less area for side winds, but high enough for reasonable comfort. Sitting on a low cushion or in a semi-reclined position gives sufficient headroom with the canvas cover in place, while sitting on the thwart seat with the birdwatcher notch open allows the head and shoulders to be above the roof.

The plan is to have two covers for the notch; an inner one of window screen mesh, and an outer one of canvas or PVC fabric, though clear vinyl might be an option. They are pulled from the front and anchored at the rear with the notch molding providing a seal.

The curvature of the sides will define most of the cabin, so I began by laying a 2x6 along the top edge of the gunwale and marking the underside with a pencil.


Rough cutting the outer curve on the side strip.  Fir was tough going for the saber saw.
I used pine for other side.  The outer edge should be exactly 90°.


Rough fitting the side strips. The planer attachment makes short work of this. The front had to be notched to fit over the foredeck reinforcement bar. Overall length is 52 inches and they will be held in place with 1/4" carriage bolt with washers and wing nuts. Closed cell foam weather strip will assure a seal to the gunwale when the project is completed.

Once the fit is satisfactory, make a line inside 3/4" from the bottom edge. This will define the inner curve, and is the guide for cutting the inner curve with the saber saw blade set at an angle to make the cabin sides angle 5° toward each other at the top.


Inner and outer curves are now defined, though a bit rough.
Use this as a template for the opposite side, keeping in mind it is a mirror image.


Final fitting of the side strips


Align the side strips, and mark so that you can see where to make the holes for screws.


Glue, screw and clamp until dry.


Both halves are up now. Adjust the angle of the gunwale strips as necessary to give the side panels 5° angle. (Or customize it to whatever angle you wish)


Drill and countersink the front edge for screws. Note: they go on the inside of the panel, not outside as it may seem in the above photo.


Using a straight edge to get the angle correct on the front reinforcing strips.

The inner edge of the side strips was used to mark the edge of the roof panels. Tracing the gunwale strip made the curve easy to make. The two panels were sanded at the same time to assure a match. Note that the grain runs thwart wise.

The gap shows where the side needs to be pulled toward the roof curve using wire before the fiberglass tape is applied..


After polyurethane glue is applied, the edges are wired together. Note the temporary brace inside the starboard half to maintain the proper angle while it is being fitted.

Applying fiberglass tape with Titebond II. I used Titebond here instead of Elmer's Probond because it is a little more flexible.  The small wood block is on top of  plastic sheet to keep small wrinkle held down.  I have discovered it is MUCH easier to glue one half of the tape, allow to dry, then do the other half. Wish I had learned that years ago. Also, using a small amount of glue will allow the "natural"  stickiness of the drywall tape to keep it held flat until the wood glue sets.

Starboard half. This was really crappy luan from Home Depot, but the bracing and fiberglass tape makes it very sturdy.

Profile view.  It is not the sleek look I had hoped for, but the elongated side windows and some horizontal trim will make it look lower and longer; a trick auto makers learned long ago. The roof curve matches the lower curve of the hull. The front cabin edge is similar. Rear cabin edge is a straight line.

Trimming the height of the birdwatcher rail with the planer attachment on the Dremel tool.
The curve matches the upper curve of the side panel.


Rear bracing and rail on starboard half. The brick you see in so many of my photos is not my pet rock. I move it from side to side to keep the boat level as I work.

This seemed like a good time to make certain the leeboard was 100% compatible.

Leeboard down


Leeboard up

The removable bridge piece was added next to hold the dimensions while the front panels were fitted. Bungee cord keeps tension.


Front notch braces are fitted. White PVC tube will (probably) become the dry well to socket the mast.
 

Front view. Hopefully I have avoided the doghouse-on-a-raft look.
After a second coat of paint and the rigging is on it should look right at home on the water.

 

Removable bridge piece is barely visible at the top. It will be attached with quick disconnect pins.  Width of the notch is about 20" at that point. Also note I have drawn a gusset in red where it needs to be stiffened on both sides. 

Gussets added


The lip, or edge at the read of the cabin is clearly visible where the fabric rear half will be cinched in place with a draw to seal it from the elements.


It is finished except for the windows and fabric notch cover.  Rear fabric portion is still in the design stage.

The fiberglass window screen is fitted to the birdwatcher opening. In this photo it is held with pushpins. Line will be hand sewn to the edges both for reenforcement, and to help keep the edges taught against the rim of the opening. Originally I had planned to use those same lines to pull the screen tight via some sort of cleat. After giving it more thought, I realized that in use it is either full open or full closed, so 1/4" bungee with hooks, and two small screw eyes at the rear should suffice. With only the pushpins holding it in place it is mosquito proof.

The dry well for the mast is visible in this photo. A boot will be on the mast to keep water from running down inside. The screen and canvas birdwatcher covers will accordion, or roll up behind the mast. Note that if the mast step were in the foredeck, this design could be greatly simplified.

 

The window frame blanks were attached temporarily with screws, and the opening traced with a pencil from the inside. (right) the halves nest together fairly well.


A sanding drum, then sanding by hand finished the opening.

After several coats of varnish, .010 vinyl film was glued to the frame with acrylic caulk. It is darker than I wanted, but I had it on hand, so I used it. The top of the refrigerator was dampened with a rag and the film smoothed to remove bubbles and wrinkles.

Caulk was applied to the backside of the frame, placed over the film and bricks used as weights. Any caulk that oozed out was wiped off  with a damp cloth. The round windows (oops! I mean portholes) will be done the same way. It is likely to take sevaral days to dry.

 

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