What fuel usage should expect for Grand Banks Classique 42?

Can't speak to those engines, and don't know your budget situation... but if you run a boat like that at "trawler speeds" most of the time, fuel will generally not be your largest expense.

For that boat, guessing a 40' waterline length, displacement speeds for best fuel economy would likely be between 6.75-8.0 kts, probably no more than 8.5 kts. (Real waterline length could improve that guess.) Absent better specifics, you could guess 2 NMPG at comfortable trawler speeds, maybe 2.5, possibly even 3 NMPG occasionally depending on wind and/or currents and tides.

-Chris

At hull speed (about 6.5kts) you re probably going to burn about 4 gph.

don’t be obsessed with fuel costs, it s only a small part of the overall budget especially with a small trawler.

You are aware this is a wood Grand Bank 42. Check it over real well before you purchase it, if you go that route.

typically insurance, dockage and maintenance are much bigger than fuel even on a fiberglass boat. No, on a woodie? Fuel will Be the last of your worries

btw many yards and marinas do not even want deal with older wooden boats… if you re up north with a fairly short season and with yards that still have people able to work on wooden hulls, it COULD BE ok but down south…. It is suicide. Look up teredo worms

In Denmark, This could be different.

But a NFG with a wood boat?
Fuel is the last of your worries, Unless you get original black iron fuel tanks..

Perhaps Monel tanks … and a copper water tank.
That’s what my 1962 Matthew’s had still fine as could be when I sold the boat in 2012.
Why manufactures get away from Monel I don’t understand I guess it’s hard to get and just too expensive?
Best metal around for a fuel tank.