Mary Jane is a round-bottom launch 17 feet 7 inches overall, with a beam of 5 feet 8 inches and shallow draft of 14 inches. This boat is powered with a small inboard engine. The cost of fuel will be very small and the tank holding a full day's supply is a permanent part of the boat, but the owner must be content with moderate speeds of up to ten miles an hour depend­ing on the load.

Mary Jane was designed for those ama-covered with canvas in the usual manner, their hand at a real boat building job on a small scale. It is a matter of opinion, of course, but a round bottom hull of light construction is not much more difficult to build than a hard chine boat. The light frames and planking are easy to handle and the experience gained from her con­struction will be valuable should a larger boat be attempted in the future.

Measuring  17 feet 7 inches, this round-bottom inboard  launch offers the challenge of real boat building, but on a small scale.

When the drawings for a boat include a conventional lines plan like that for Mary Jane the only proper way to start building is to redraw the lines full size in their en­tirety.    When carefully done this job will take a full day's work at the very least, but will pay dividends throughout the con­struction. Drawing full size, which is done on building or drafting paper or on ply­wood panels, is called mold lofting.

Molds to shape the boat are made from the body plan sections. A mold for each station is made of rough lumber and, to shape the hull in the spaces between the molds, wooden strips called ribbands are bent around the molds from stem to stern. The ribbands are closely spaced from keel to sheer to insure a properly shaped hull. Mary Jane is best built upside down, in which case the frames are steam bent on the outside of the ribbands. As the lines for small boats are drawn to the outside of the planking, this means that the thick­ness of planking, frames and ribbands must be deducted from the body plan sec­tions before making the molds. If a hull is built right side up, only the planking thickness is deducted, for then the frames are bent inside of the ribbands and the ribbands are removed one by one as they interfere with the planks being applied.

IMENSIONS IN FEET-INCHES - EIGHTHS (TO OUTSIDE EDGE OF PLANKING)

The keel and stem are drawn on the full-size plans so that templates can be made and the shapes and rabbet lines trans­ferred to the lumber for cutting. The shaft line also is drawn in, then transferred to the keel template as a guide for boring the shaft hole. In turn the engine beds are cut from a template made from the full-size drawing. Thus, when the transom, tran­som bevels and the stem and keel rabbets are considered, along with the molds and backbone members, the lofting is really essential work right at the beginning.

After setting up and rigidly bracing the keel and keel batten, stem, transom, molds and ribbands, the frame locations are marked along both sides of the keel at the rabbet, then the keel batten is notched for each frame. Cut the notches with a chisel, deep enough to hold the frame ends.

Before planking, the entire backbone and frames should have two good sopping coats' of a copper naphthenate preservative such as Cuprinol; also coat the deck shelf before the decking is laid. Such a preserv-tive is inexpensive and very much worth while as a preventive of rot.

The planking is to finish ½ inch thick, so it must be ordered ⅝ inch to allow for planing smooth and sand-papering, also for hollowing the inside and rounding the outside of the planks on the hard turn of the bilge in the after sections of the hull. The plank fastenings to the frames can be copper nails riveted over burrs instead of the screws called for on the plans, but whether rivets or screws are used the planking is too thin to counterbore for plugging the holes. Instead, countersink the heads to a depth not more than ⅛inch less than the plank thickness and fill the holes with composition.

A boat like the Mary Jane is compara­tively easy to finish after the hull is completed. There   are  but  a   few   deck beams to cut and fit as the side decks are laid on a shelf instead of beams. The tongue-and-groove straight-laid decking is simple but sufficient for this boat when covered with canvas in the usual manner. Seats, too, are simply made, and the out­board rudder could not be much easier to make and install. The mechanical depart­ment is the minimum, consisting of engine and exhaust, shafting and fuel tank. There should be a shut-off valve at the gas tank outlet and a strainer close to the valve. The copper tubing fuel line must have a loop to absorb vibration. Make the loop about six inches in diameter and locate it a few feet from the engine. Insulate the exhaust pipe where it is exposed between the en­gine box and the place where it runs under the seat on the port side. Make the engine box with portable sides and top. The for­ward side, of course, is the access to the flywheel for starting the engine.

Paint the boat with good marine grade coatings, using anti-fouling paint on the bottom below the boot top stripe. Many of the paint manufacturers have booklets ex­plaining how to finish all boat parts.

The boat must be outfitted as required by the U. S. Coast Guard for class 1 motor boats. The compulsory items are few and all are for the boatman's protection. For anchoring, either a 15-pound yachtsman's type kedge anchor or a 10-pound Standard Danforth anchor should be provided and 125 feet of ½-inch manila line.

LARGE  SCALE  BLUEPRINTS  will simplify construction.  Send $5.00 to Twenty Boats Plans Dept.. The Rudder Pub. Co.. 9 Murray St.. New York 7. N. Y. Specify Plan FB-362 Mary lane.

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