| That is certainly a compact little installation. A shame the servo motor didn't work and I'm surprised as I use servo motors to drive my Revel u-boat through 10" shafts.
Anyway, as you say, you do need a bit of power in hand for those unforseen manoeuvres by other vessels.
As for a barge have a look at the Springer Tugs section of modelboatmayhem.com forum where I posted a series of pictures of a modern fuel barge which would be very straightforward to make.
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“Dirty British coaster with a salt-caked smoke stack, Butting through the Channel in the mad March days" | 
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