Build a Cartop Carrier/Folding Boat

Confronted with two unfavorable alternatives — buying an expensive boat or doing without one on camping trips — the author decided to build a cartop carrier that also functioned as a folding boat.

| March/April 1989

It's not often that you can have your cake and eat it too, but if you find yourself whiling away your free hours outdoors — camping, boating or just messing around — and don't mind spending about $100 and a few days of that leisure time puttering with a delightfully simple wood project, that luxury can be yours any time you please. This 8-foot-long craft isn't just a water-worthy two-person row-boat, but at the flip of a latch becomes a lock-able, weatherproof cartop carrier built to hold about 30 cubic feet of goods that might otherwise have been left at home.

As a water lover — one who plans outings and vacations around fishing, lakeside camping and searching out ponds and rivers — I faced a choice: Hit the deep blue by laying down some long green for the purchase of a proper Johnboat (and perhaps a trailer, registration, and towing package on top of that), or go on camping trips without. Neither option appealed to me, so I took a third tack and, although I'm no boatwright, chose to build a folding boat from scratch, using basic techniques and materials simply because that's all I had to work with.

All told, the "cartop dinghy" project required three 4 ft x 8 ft sheets of quarter-inch marine plywood. [Editor's Note: Similar boats have since been built using the less expensive B-C exterior panels, but it's still anyone's guess as to how well they'll hold up over time.] In addition to the plywood, I used 10 strips of 3/4" x 1 1/4" blind stop (a thin piece of rectangular molding) — about 100 linear feet altogether; they come in random lengths of 10 feet to 12 feet and should bow without breaking, a 26-inch scrap of 1 by 4, a 11/2-inch by 4-foot section of brass-plated continuous hinge, two 1 1/2" x 3 1/2" galvanized safety hasps, six reinforced staple plates to fit the hasps, two 3 1/2" eyebolt snaps and a 1 1/4"  x 3 3/4" locking draw pull catch.

I salvaged the oars and pinned lock sets from another boat. You'll need two pairs of oarlocks for this dinghy, since they also serve to secure the oars when the vessel's folded, creating a convenient set of carrying handles. Four small eyebolt snaps hold the lock shafts in place.

For fasteners, I bought 800 No. 6 by three-quaters-inch anodized drive screws, 18 in a No. 8 by 1 1/2" size and 16 more, 3 inches long. Eight No. 8 32 by 1-inch flathead machine screws and 32 No. 8s, each 3/4" in length, were used to hold the metal hardware. The wood joints and seams were glued and sealed with four 10-ounce tubes of exterior construction adhesive. Finally, to button up the box along the edges when it's used as a carrier, I cut two 12-inch by 48-inch strips of colored vinyl fabric and bought two dozen pairs of plated snap fasteners.

By this time, you're probably ready to get to work on your own boat. Got two sawhorses and a sharp pencil? Start by marking center lines (for reference) across two of your full sheets of plywood, diving each into 4 x 4 squares. Now, refering to our Assembly Diagram, mark off the outlines of the center bulkheads, the front and rear transoms, and the two seats.

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