it say's it got that OL to 112 mph . that's pretty quick in my book , but they didn't say if they where using multi speed tran's thow .
also 1.5 mpg @ 90 mph but that's with 4 motor's so if you had say 2 motor's and cruised @ 60 mph i wonder how much fuel you will burn ? if you where to take the 1.5mpg and x by 2 for half the motor's that's 3 mpg. and say a slower cruise speed of 60 mph wouldn't be bad fuel burn for the average boater
also in say a 40 to 45 ft boat
It has to do with how much Hp it takes to go that speed, the engines burn 212 grams per kW hr. At 60 mph maybe your at 60% power say 275kW?
275 x 212 = 58,300 grams or 2056 oz divide by 16 and that's 128.5 lbs or 18 gals/hr and that making 370Hp ea or a total of 72 gal/hr.
I think my math is a little off, that much power and you would probably be in the 80 mph.
I'm guessing 60 mph like you asked is 200kW so
200 x 212 = 42400g = 1495oz = 93lbs = 13.5 gal or 53 gal/hr total
with the new style of fuel injection i think they get better fuel mileage , the 480 cummins list 25 gph@ 3400 rpms and the fpt list 28 gph @ 3000 rpms .
i think i remember the eliminator 43 twin cummins boat running 70 to 75 mph top speed and that would be 50 gph @ 3400 rpms so to cruise @ 60 mph it should be burning a bit less then that i would think .
Mike I know I didn't answer your question exactly and it had nothing to do with old vs new engines, it was more me putting too many variables into the answer i gave you - I'm sorry I get carried away!
To answer you, I took the fuel consumption right from FTP's site, you said 2 engines but I played it out for the 4 engine boat but for your 2 engine boat it most likely would be somewhere between 27 gal/hr and a max of 36 gal/hr for your 60 mph cruise.
Whay the range - I'm trying to figure how much Hp to go that fast, I know it will take about the full 380hp we used to have to make a SH 40 fully loaded in patrol boat trim, that has to weigh close to your Fountain cruiser? So, at FPT's burn rate of 212 grams of diesel to make 1 kW of power then convert all that back to gal/hr and you're at roughly 18 gallons per hour. Times 2 is 36 gals per hour.
I'm guessing the Fountain might be lighter and probably a better hull you might be down to the lower 200kW per engine to get to 60mph hence the lower 13.5 gal/hr or 27 gal/hr total.
That is where I think you will be a low of 27gal/hr and a high of 36gal/hr.
If you do this I would love to come down and visit with you while you start to sea trial!
Habana, my point on the learning curve is somewhat like installing Ilmors vs Merc...there is somewhat of a learning curve or resisitance in change to get to the final product. The masses still want gas, and the builders other than a few prefer it that way, even though the costs of said motor/tranny/drive are not any more, actually less in some cases...just the mind set of how much more labor will be due to not doing it enough times...ends up being slightly more. Set up is crutial, gear ratio, multi speed trannies is questioned of possibly being more problomatic vs std setup. I wish more customers would go the diesel route, I still love the idea, just couldnt get a third motor in the 43 to get the speeds I wanted. She went 74mph with the twin 480hp Yanmars and ASD-8's. There is nothing in between hp range power to weight ratio that would work to obtain low to mid 80's..., or I either do what my Hero Bob did, just order a lighter 50. If Yanmar or Cummins would come up with the same hp/tq as FPT did then hey...maybe 80mph+ would be a great set up, and work for poker runs where my sticks wouldnt be to wall...until then, Merc 700's were the snizel in that boat..Have a great holiday. Jeff
but i am looking into getting another boat in the near future.
some where between the 40 and 45 ft range 8 to 8.5 beam .
when this does happen you can come down anytime to check out the boat and help dial in if you want . and im sure at that time i will have a lot of question's on gear ratio and other stuff .
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