Apologies, I don't know the tandem lingo, but here's how I understand it. Captain has a double crankset with a chainguard where the big ring would be and a 30t middle. Stoker has a triple, with no inner, a 30t middle that joins up with the captain, and a 50t outer. the 50t outer gos to an 18t cog on an alfine hub.
It runs really nicely, and the versa shifters work beautifully with the alfine hub - much nicer than the various twistgrip nexus 7/8 setups I've had over the years.
Went for our first decent run out on it this morning - 40km ish, with my 5 year old on the back. Averaged around 25kph without trying hard. Probably going to do the
110km R101 as our first event on it, but were taking it on a cycling holiday before then. He went to sleep without any fuss this evening, so I'm hoping he'll be putting himself to bed once we start getting out properly on it.