Triple-Screw Boat in River in Boston

[Queequeg QuintParticipant @queequegquint38270]

I originally shared this video in the Build Blog section, but since I’m no longer building it, I’m putting it here.

It’s my triple screw boat that I designed a couple years ago. It’s running three MFA Como Drills 800 motors, turning three 55mm five-blade brass propellers, on a 12-volt NiMh battery pack with 8400mah. One MTroniks ESC operates the center motor, another MTroniks ESC operates the two outer motors. The center motor and the starboard motor turn counterclockwise as you face the stern of the boat (looking at it from behind the boat, that is). The port motor turns clockwise.

When running all three motors, the turn radius is not too good. But when I deactivate the center motor, the turn radius is beautiful. Same if I operate only the center motor.  The boat has three rudders, one behind each propeller. I The rudders are so effective at keeping the boat in a straight line– they give the boat the appearance of riding on a submerged rail!

Having a third propeller did not significantly increase my speed, but it does give me great authority at lower speeds. I truly love the uniqueness of having three propellers.

The runtime is splendidly decent, probably over 40 minutes. That surprised me, because I thought the battery would drain quickly.

I usually don’t drive this boat on an open river, but on this day, the river was unusually calm — except when an angry police boat drove by quickly to warn kayakers to get away from the fireworks launching site which had been set up for the Fourth of July here in the United States. His boat would create a huge wake! When he would create a big wake, I would send my triple screw boat out toward the middle of the river, and try to hit his waves going very slowly and at a slight angle.  Seems to work nicely everytime.

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