Bonjour,
I have never seen any Chiltern steam machine in France. Their twin are B14xS18 mm = 11 cm3, when a TVR is "only" a 8 cm3.
A usual, the question is "Which boat for such powerful steam machines" ?
Of course, the theory allows calculations, but I prefer experience. Based on my collection, for a 8 cm3, I would use a boiler which would provide a minimum of 750 ml useful water to hope more than 20/25 minutes of autonomy (or plan an additional water pump)==> appropriate size tank too.
For a 11 cm3, no feed back, I have no one...Yet...My 10V has two possibe boilers but not yet tested.
The equation 1 cm3 = 1 kilos is wrong (*), lack of parameters, I have many ratio 3,5 / 4 boats which are already too fast for their scale.
(*= For the boiler, 1 cm3 = 10cm3 of heat surface seems quite more correct and appropriate than just a very powerful gas torch.