AN ELECTRIC SUBMARINE-CHASER
THE submarine chaser design given in the drawings and described in the
text of this Chapter is a presentable little boat with pleasing lines
and deck fittings. There is nothing difficult about its construction,
and, considering the amount of work necessary to produce it, it is
probably one of the most pleasing boats described in the book. If made
correctly it will look "speedy" and shipshape.
The general outline of the boat can be gathered from Figs. 86, 87, and
88. Fig. 86 gives a side view of the craft; Fig. 87 shows the bow, while
Fig. 88 gives the deck-plan.
[Illustration: FIG. 86]
[Illustration: FIG. 87]
[Illustration: FIG. 88]
Notice first the construction of the hull. This is made according to the
Sharpie type, but the lines are changed to give the boat a more graceful
appearance. This is done by changing the shape of the deck and the
bottom pieces. Fig. 89 shows the various pieces necessary to construct
the hull. It will be seen that the forward portion of the bottom piece
is narrower than the deck piece, and broadens out so that it is wider at
the stern than the deck piece. The deck piece has a maximum width of 5
inches, while the bottom piece has a width of 4 inches at the forward
section. The deck measures 3-1/2 inches at the stern, while the bottom
piece measures 4-1/2 inches at the stern. This produces a half-inch
taper on each side of the stern. A half-inch taper is also produced on
the bow portion.
[Illustration: FIG. 90]
[Illustration: FIG. 91]
[Illustration: FIG. 89]
The hull of the boat can be made from 1/8-inch mahogany. If this is not
available, choose some other close-grained wood, free from knots and
blemishes. Paper patterns are made to correspond with the general shape
of the pieces that form the hull as given in Fig. 89. The pieces, after
being marked, are cut to shape with a keyhole-saw. After this is done
their edges should be trimmed neatly with a jack-plane.
The two sides pieces are now screwed to the bow piece by small brass
screws. After this is done the bottom piece is fastened to the side
pieces the entire length of the boat. Next the first cross-piece, as
shown in Fig. 90, is screwed in place. This cross-piece should be 4-3/4
inches in length, so that the width of the hull at this point is just 5
inches. The next cross-piece should correspond to the width of the deck
piece at the section of the hull where it is placed. The same holds true
for the third cross-piece. When the third cross-piece has been screwed
in place, the stern piece is put in position.
The joints of the hull should then be smeared with either pitch or
bath-tub enamel or a thick mixture of white lead may be used.
After having made sure that the hull is perfectly water-tight the worker
can proceed to install the power equipment. This consists of a small
battery motor driven with two dry cells. The design and installation of
such things as stern-tubes and propeller-shafts have been taken up in
detail in an earlier part of this book. The strut that holds the
propeller-shaft is shown in Fig. 91. This consists merely of a brass
bushing held in a bracket made of a strip of brass 1/2 inch wide. The
brass strip is wound around the bushing and soldered. It is held to the
bottom of the hull by means of two 8-32 brass machine screws. These
screws should be tightened to prevent leakage. It would be inadvisable
to use wood-screws for this purpose, owing to the fact that the bottom
piece of the boat is thin.
[Illustration: FIG. 93]
[Illustration: FIG. 92]
The two dry batteries for the motor are held in two tin troughs, as
illustrated in Fig. 92. These troughs are fastened to the side of the
boat by means of small bolts. They will prevent the boat from shifting
its cargo; in other words, they hold the batteries in place and thereby
prevent the boat from listing.
The deck and deck fittings should now be furnished. The construction of
the forward cabin is shown in Fig. 93. The sides and back are formed
with cigar-box wood, while the curved front can best be made with a
piece of tin. The top is also cut to shape from cigar-box wood, and
should overlap about 1/4 inch. The pilot-house is simplicity itself,
being made of a piece of curved tin with three windows cut in it. Four
little lugs cut in the tin are bent on the inside and each provided with
a hole. These lugs are used to tack the pilot-house to the deck. A small
skylight is produced from a solid piece of wood and tacked in place as
illustrated in the drawing.
The builder is cautioned not to destroy the appearance of his boat by
making the mast too large. After the mast has been nicely sandpapered, a
little wire frame is bent to shape and fastened to the top, as shown in
Fig. 87. The little wire railing that is placed in front of the mast is
then bent to shape, and this and the mast are put in their permanent
position. The mast can be held to the deck by boring a hole a little
under size and smearing the bottom of the mast with a little glue before
it is forced in. Pieces of black thread are run from the top of the mast
to the railing at the bottom, as shown. These threads are used to hoist
signal flags. Two little angle-pieces are placed on the forward deck,
one on each side of the pilot-house. These are for the harbor lights.
One should be painted green and one red.
This finishes the forward cabin. It should be placed in the center of
the deck and the position it occupies should be marked out with a
pencil. This portion of the deck should be carefully cut out with a
coping-saw. The cabin is then forced into the opening. The fit should be
fairly tight, so that it will not be necessary to employ nails or glue,
as this is the only way in which the interior of the hull is made
accessible.
Two ventilators are placed just back of the forward cabin. Between the
forward cabin and the cabin aft there is placed a rapid-fire gun. The
details of this gun are given in Fig. 94. The barrel of the gun is made
of a piece of brass rod. A hole is drilled through this rod with a small
drill and a piece of copper wire is inserted. A square piece of brass
for the breech is then drilled out to receive the barrel. One end of the
barrel is placed in this hole and held with a drop of solder. A drop of
solder should also be used on the copper wire that runs through the
barrel. The bearing and shield of the gun are made from thin sheet
brass, as illustrated. Three holes are drilled in the bearing bracket,
two through which the wire passes and one through which the small nail
is placed to hold the bearing to the wooden standard. The shield is
forced over the barrel and held in place with a drop of solder. When the
barrel is mounted in the bearing, a drop of solder should be put in
place to prevent the barrel of the gun from tipping.
[Illustration: FIG. 94]
The cabin which is placed aft on the boat, is of very simple
construction. It is made up entirely of cigar-box wood tacked together,
and the top should overlap 1/4 inch. The cabin is then tacked to the
deck of the boat. The mast should be only three-fourths as high as the
forward mast, and a tiny hole is drilled near the top. Into this hole a
small piece of soft wire is placed, and from this wire a thread runs to
the cabin. A small flag can then be placed on the thread, as illustrated
in Fig. 86.
Six port-holes are now bored in each side of the hull with a 1/2-inch
bit. These can be backed up with mica or celluloid. Five smaller
port-holes made with a 1/4-inch drill are then bored in each side of the
forward cabin. Three are placed in the aft cabin.
With the exception of painting, the hull is now ready to be launched.
Before finally applying the paint the hull should be given a thorough
rubbing with sandpaper. A battleship gray with maroon trimmings makes a
pleasing color combination for this boat.