What to do

1. Take the 400 mm length of timber and give it a vague lizard shape (a thinner tail and thicker body). This makes it more lizard-like and reduces any buoyancy the tail may have had to give a better running angle. Angle the front underside of the wood to give it a more streamlined shape (and possibly to give it a small amount of planing lift once moving).

2. Next step is to fix the gearbox onto the 40 mm length of aluminium angle. Drill four holes in one leg of the aluminium angle, to match the mounting holes at the drive shaft end of the gear box. Then make a hole in the centre of that angle leg, to pass the drive shaft through.

3. Drill and countersink two holes in the horizontal leg of the angle. Use two 1” wood screws to fix the horizontal angle leg to the top surface of the wooden cut out, with the vertical leg standing 60 mm from the front edge of the timber. Fix the gearbox to the vertical angle leg so that it is right at the front of the lizard, with the drive shaft pointing towards the tail.

4. File a 3-4mm wide flat on each of the three shafts coming out of the gear-box. Next step is to attach the ‘legs’. First, cut three 20 mm lengths of solid ½” aluminium rod. Then drill a 5 mm diameter hole down the centre of each one. Next, drill a 3.5 mm diameter radial hole at one end of each of the three aluminium rods. Use an M4 tap to give this a thread, so that you can put an M4 grub screw in to fix it to the shaft. At the other end of the two rods, use an M6 tap to make an M6 thread. Then drill a 3 mm hole through the diameter of each of these two rods, about 6-8 mm in from the M6 tapped end. (The 3 mm hole is to accept the 3 mm diameter steel rod used for the lizard’s legs).

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