8 kts on a 48 is way less power than 10kts on a 54. 8kts on a 48 I'll guess 1.5-2nm/gal. Well below hull speed at 8kts. 10kts on the 54 is trying to climb the hump, lots more power needed.
I believe that the 48 carries 560 gallons
I have a 1989 48' Californian aft cabin with 3208/375hp. I have ran against the current on the Cumberland River averaging 12-13 mph and only got 1 mpg. On my return trip I slowed it down a bit to 9-10 mph running with the current and got 2 mpg. Both ways the generator was running also. Sorry but I don't have a better fix on it than that. I would expect if I would hold it down to 8-9 mph I would get a little better. One of the other posters mentioned that the 48 carries 560 gallons. I am pretty sure that is correct. I think I have two 200 gallons on each side and a 160 gallon aft tank.
I'm trying to estimate fuel costs for a long transit in a 48 Californian Aft Cabin MY running 3208TA's. Speed around 8kts. Any help out there?
Thanks,
Jerry
Jerry:
I have a 55' CPMY with same 3208TA's. 8 -10kts is prime cruising speed and there are multiple factors in running. My manual also says that for every 2 hours at lower speeds you need to run at WOT for 2-3 min. I have a GPH meter but won't help you much as my set up will be much different than a 48 but for what it is worth I get 3gph at 8.2kts and 5.9gph at 10kts.