The chassis is a catamaran made from two Zeppelins from LEGO's 5956 Adventurers
sets. Unfortunately, the Zeps are constructed in two pieces so that you can
unscrew the tail section to store stuff inside the body. I thought it would be easy to seal
the join between the two pieces, but all the mastic sealants I tried leaked! Then
I realized that I could just tape the seam between the two pieces with vinyl
electrician's tape (duh!).
The arms are driven by the CyberMaster's two built-in motors. Each arm is essentially
a three-bar linkage driven eccentrically by a 40t gear mounted on each of the motors.
The arms 'strike' and 'set' the oars (lift them in and out of the water). One problem
with mounting the CyberMaster in a vertical orientation like this is that the CyberMaster's
two flexible radio antennae stick horizontally out of the rower's 'chest', so I bent them
upwards. They were still sticking out a good long way above the bot so I decorated
them to look like a face.
The CyberMaster unit is contained in a cradle which moves back-and forth along a
'slide' of inverted 1x16 Technic bricks either side of the chassis. The slide bricks
have their undersides covered with 1x4 rack pieces.
The third (external) motor drives a motor-14t:40t-8t gear-train. The 8t gears at
the end of the gear-train engage the rack pieces on the underside of the slide to
move the CyberMaster unit back-and-forth. The back-and-forth motion is geared way
down compared to the arm motors so that the 'strike' (removing the oars from the
water) is quick enough that the bot does not come to a dead stop in the water.
The oars are made from three lengths of 1x16 Technic Bricks with black plates for
the 'blade' and the loom coming to a linkage to the robot's arms. The outriggers
which support the oars are able to hinge upwards. The hinging allows the outriggers
to move up with respect to the surface of the water if the oar blades hit something
other than water (like a lily-pad).