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the profile that the stuffing box will have. This will minimize the need to add filler
material later. If you are using an off-center driveshaft, be sure you cut appropriately.
ABS: READ STEP 9 NOTE BEFORE CUTTING! After the glue from Step 6 is
cured, use a sharp hobby knife to cut the Area A out of the hull. You may wish to round
the ends of the cut in order to allow them to more closely match the profile that the
stuffing box will have. This will minimize the need to add filler material later. If you are
using an off-center driveshaft, be sure you cut appropriately.
9) Assemble the drive train components: bushings, driveshaft, motor coupler, motor, and
motor mount (already installed in boat). Set your stuffing box in place so that the motor
end does not have any misalignment; the flexible coupler should naturally bend to accept
the motor driveshaft. Set the rear end of the stuffing box so it is about 5/16” below the
transom, and so that it extends about ½” past the transom. The actual position fore/aft
will be determined by the other drive components, and this is the reason for you to
assemble the system completely at this point.
NOTE: If you are using a high-power motor (other than the Graupner 700 BB which
comes with the GR1157), you should set the driveshaft at a lower angle. Our racing hulls
(using custom hardware) are set so the end of the driveshaft, the center of the driveshaft
is 1/16” below the lowest point of the sponsons at the transom. This also allows the use
of larger props on the 700BB motor, but it changes the position of the Area A cut-out.
10) With the drivetrain in place, tack it in position using some gap-filling CA and accelerator.
Be careful not to use too much CA –you want to use epoxy to make the joint strong. The
CA is just a tool to hold alignment.
If you are building this boat for racing or plan to use higher-power motors, you should at
this time add two lengths of fiberglass or graphite tubing to extend from the forward
cross-brace (in front of the motor area) to the balsa bulkhead or radio box. These will tie
the motor mount, stuffing box, and hull together in order to make the boat stiffer. We
recommend using fiberglass pushrods from Dave Brown Products for this purpose.
These are available at your local hobby shop. Use epoxy for fiberglass hulls, or JB Weld
or thick CA for ABS hulls.
11) FIBERGLASS: Use a thickened (with micro balloons) 5-minute epoxy to seal the
opening around the stuffing box. If you have some glass cloth, it may be used to further
strengthen the joint when applied inside the hull. BE SURE TO KEEP THE
DRIVETRAIN PROPERLY ALIGNED WHILE THE EPOXY CURES!