How far can you go?

[ransflyer]

How far can a cruising catamaran motor?

Let's say it is a common model: Lagoon 440
Standard tanks: 325 liters x 3 or 257 gallons (+ 5 gallon can for emergency reserve, but not counted in the range)
Side question: can all three tanks be used by the saildrives or is one tank dedicated to the genset?
Bottom is newly painted and clean.
We are trying to maximize the range so we'll use just one 55 HP engine at 4-5 knots in the doldrums with zero or cancelling winds and relatively calm seas. Boat is fully loaded with gear, provisions, etc.
Flex-o-Fold 2 blade prop (or other, please specify)

Lagoon manual says light displacement is 10,500 kg, Max load disp in theory 13,500 kg with an authorized max load of 5900 kg. Not sure what that means. Maybe someone can help me there.

There are likely other factors that I've forgotten. I'm interested in both the theoretical and real life expertise of the forum. This may help us understand the difference between electric and diesel better, though I admit I'm very seriously considering electric given new battery and solar technology.

Again, this thread is about diesel engine range on a cat. I'm intereested in all brands/models so if you have other actual numbers to share, please don't be shy.