We try to stick to one canal and follow it to the end...
Our boat is also a former army boat. We found some distinct army colors under the thick layers of more recent paint, and we also have some big holes in the front deck, though I am not sure if these were for mounting machineguns. We were told however that the boat was mainly used for R&R by army officers.
The round window is indeed original, check this old picture* for comparison:
As for the engine in our "officer's boat": it's a GAZ-49b engine, which is a slightly more modern version of the original 6 cylinder GAZ-53 engine. This 49b engine came out of a BTR-60 armoured vehicle (which had 2 of them) and supposedly has 110 BHP, although I heard that our engine has 90 BHP. Not sure what is the right value. In any case, it's about as thirsty for gasoline as a you'd expect of a old military engine like this, so we're hoping to put in something slightly more modern, slightly more powerful and slightly less thirsty soon. And definetely a diesel.
Btw, I like the color-scheme of the Volga of your friend! The white will make very visible that the whole boat is really 'flying' above the water! Is this boat by any chance one of the boats owned by (family of) the real-estate agent with an office on the Prinsengracht?
(* not sure anymore where I found this picture. To whoever owns the copyright to this image: please make yourself known so I can mention your name)