THIS is a highly versatile craft. She is the ideal trailer size, light enough so that there are no handling difficulties, but able enough for a day's enjoyment in most waters. Stability is such that passengers can stand and walk about without concern and she will carry five persons. Firefly makes an adequate and handy fishing boat for anything except offshore work.

SPEED

Of considerable importance is the ex­hilarating performance attainable with en­gines of 30 to 40 horsepower. Speeds in excess of 30 miles an hour can be reached with safe banked turns. Firefly has the speed and lifting ability for water skiing.

Construction methods shown are well suited for a home builder or for a small shop. The straight sheer facilitates the use of a solid sawed harpin. Such a harpin contributes to ease of alignment and in­sures a smooth, accurate curve at the sheer. Longitudinal hull battens are laid on the outside of the frames rather than notching the frames for the battens. This is done both for ease of construction and to give a uniform pattern of deflection to the ply­wood under load.

It will be noted that the batten nearest the chine log is spaced only one half as far away as the other battens are from each other. This is to minimize deflections at the edge of the plywood sheet and thereby minimize the chance of the plywood work­ing loose and developing a leak.

Speed, stability and portability with room for five—that's the promise   of   this   versatile   plywood   and   Fiberglas   14-footer.

LOFTING

Lofting or laying down the lines merely consists of drawing the lines full size by referring to the lines drawing and the table of offsets. Smoothly faired curves should be drawn through the measured points and any discrepancies in the offsets should be faired into smooth curves. The only straight lines are the sheer in profile, the transom which slopes 12 degrees to the waterline and the after portions of the chine, buttocks and fairbody. The fair-body, which is parallel to the keelson, is a straight line from the stem to the transom and it is extremely important to the plan­ing performance that this be a straight line on the finished hull.

At this stage the builder should decide whether he prefers the boat with or with­out fins. The fins shown are restrained and blend with the character of the boat. Small fins have no discernible effect on perform­ance so they can be considered strictly a matter of personal choice.

To find the outline of component mem­bers it is necessary to deduct the thickness of the ¼-inch plywood. Notice that the harpin is located ¼ inch below the sheer line to allow for the thickness of the deck­ing. The ¼-inch deduction must be made on the harpin, stem, transom, chines, keel­son, deck members and on frames 1- and 2. On frames 3, 4, 5, and 6 a ¼-inch deduction for plywood and a further ¾ inch for the battens is made. Battens are not notched into these frames.

FRAMES AND HARPIN

Any light wood can be used for the har­pin including cedar, sitka spruce or ma­hogany. The frames are sized for light woods such as mahogany or yellow cedar and if oak is used a reduction in molded width of ½inch should be made. The floors are of solid stock, glued and bolted with ¼-inch carriage bolts. The chine joint is made with ⅜-inch plywood gus­sets on each side glued to the frames and fastened with ¼-inch carriage bolts. Sheer gussets or knees are of the same material as the frames. The tops of the frames are cut to fit the underside of the harpin.

STEM

Fir, mahogany or oak strips, sawn ac­curately to 3/16inch thickness, coated with a cold setting resorcinol glue can be bent to the required shape and clamped at six inch intervals to produce a laminated stem. It is particularly important to apply sufficient heat to properly cure the glue lines. A rabbet is not used in plywood construc­tion since it reduces the effective bearing area of the plywood edge.

The transom is cut from ½ inch marine plywood—either mahogany or fir.

It is advisable to study the framing mem­bers and the construction of the watertight outboard well rather carefully and to in­stall the hard to reach members first. Al­though a watertight motor well involves additional work it is important to the sea­worthiness of a highly powered 14-foot runabout. This size of boat should have a short shaft engine to keep the center of gravity down but the deep transom cut-out introduces the possibility of swamping in a steep chop. A watertight motor well solves that problem. It also strengthens the transom and provides a handy spot for a battery and tools when working on the engine.

The transom side frame is of ¾-inch stock notched for the battens. The bottom frame is of double ¾-inch stock with only the forward thickness notched for the chine logs, battens and keelson. A 1¾-inch by 5-inch oak or fir motor board is notched around the side frames at its ends. Note that the motor well deck is fastened to the transom motor board before the transom is erected on the harpin.

SETTING UP

The hull is built upside down. A build­ing base of scrap lumber should be as­sembled 12 to 18 inches above the workshop floor level. This base, consisting of six or seven 2 inch by 3 inch or 2 inch by 4 inch members, 5 or 6 feet long, laid out at about 2 feet on center, should be perfectly level. The harpin components are tacked to the base in their proper relationship, but up­side down. Frames, transom and stem are all set up and temporarily braced into po­sition and held by the fir keelson which is 1½ inches by 3⅝ inches. The keelson is glued to these members and fastened with four ¼-inch carriage bolts to the stem and two 2-inch No. 10 flathead screws to each frame and transom. These screws are countersunk ⅜ of an inch. Alignment of the frames should be checked and slight errors in beveling faired out.

Inner chine logs of select ¾-inch by 3-inch white oak are next bent into place, glued and fastened with two 1½-inch No. 8 flathead screws pulled just below the sur­face of the wood. A hull that is out of alignment will give poor service.

At this stage alignment of the entire structure should be carefully checked and the battens temporarily laid into place to see that they fit fairly.

The battens of ¾-inch by l¾-inch oak are glued and fastened with two l½-inch No. 8 screws. As shown on the construc­tion plan all battens terminate short of station 2 and the ends of the battens are tapered to -3/16inch thick over a length of one foot.

PLANKING

Before beginning the planking, make certain that all of the relatively inaccses-sible components at the stern such as the triple knees and motor well deck are in place and fully fastened. Bevel chine logs, keelson and all of the other members to give a perfectly fair landing for the ply­wood planking.

First the topsides are covered with two sheets of Vi-inch by 24-inch by 15-feet full length marine plywood. Rough trimming is done before application and the plywood should be laid in Dolfinite seam compound. Work from amidships fore and aft, fasten­ing with ⅞-inch No. 8 flathead screws spaced 4 inches on center on battens, 3 inches on center at chine and harpin and 2 inches on center at stem and transom. Drill a slight countersink to pull the screws just below the surface. Use socket head screws and an electric screwdriver. Butt the ply­wood at the stem.

Apply both sides of the boat at nearly the same time and do not leave the hull over a day with only one side planked as this will cause distortion.

Bevel the topside planking flush with the chine log to receive an overlap from the bottom extending from the transom to ap­proximately station 3. From this point forward, trim the topside planking in a smooth line to the stem with the edge per­pendicular to the chine log surface, in other words, square off the plywood edge over this length.

Bottom planking consisting of two sheets ¼inch by 3 feet by 14 feet is applied sim­ilarly. Planking is butted at the keelson and stem. The screws are spaced at 4 inches on center on the battens and at 2 inches on center on the keel, chine logs, stem and transom. At all times take note of the wood grain before driving a series of screws.   Bevel the plywood along the centerline for the keel and the stem molding.

FIBERGLASSINS

Although this hull can be built without the Fiberglas finish the designer prefers to see it used on the bottom and topsides. It should be applied at this stage of construc­tion before the keel or outer chine logs are fastened in position.

 The oak keel is fastened with No. 10 screws staggered at 3 inches on center and of lengths as required.

The importance of the outer chine log in a planing hull cannot be over-emphasized. It acts as a spray deflector and the lower edge should be trimmed horizontal from the station forward of the transom to the forward sections where it is tapered off. Fasten the outer chine log with 1¼-inch No. 10 flathead screws spaced at 3 inches on center and staggered. The hull is now turned over and the planking trimmed flush with the harpin.

Deck beams are cut and fitted as shown. Fastenings to the harpin are two 2-inch No. 10 flathead screws at each beam.

Decking can be of mahogany plywood finished bright in keeping with the style of the boat. Set the plywood in Dolfinite on the beams and fasten with ⅞-inch No. 8 oval head plated brass screws spaced at 2 inches on center around the sheer, 3 inches on center in the beams and other backing members.

TANKS

It is suggested that one 12-gallon perma­nent gasoline tank be installed as illus­trated to reduce the fire hazard. Most outboard motors are alternatively equipped with a fuel pump. The tank should be se­curely chocked and properly vented. If a portable tank is preferred place the aft seat at the correct height to accommodate your particular tank.

A half-oval chrome molding can be used to advantage around the sheer and down the face of the stem. If possible use the molding with the slightly concave back to get neatest job. To dress up boat, designer suggests using a padded leatherette coam­ing and colored leatherette cushion seats.

LARGE  SCALE  BLUEPRINTS  will  simplify construction. Send $15.00 to Twenty Boats Plans Dept., The Rudder Pub. Co.. 9 Murray St.. New York 7. N. Y. Specily Plan FB-362 Firefly.

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