Fuel burn Starcraft chieftain 21'

[list249]

Hello all, I'm rebuilding a 1971 Starcraft Chieftain withe the Mercruiser 165hp. Not sure what size fuel tank ill need, anyone have one of these that can report gph or mpg? I need a 250mi range. Thank you.

 

[Scott Danforth]

your fuel burn will depend on the amount of power it takes to get the boat to operate the speed you want in the conditions you encounter.

if you need 250 mile range, shoot for a 120 gallon or larger tank. assume 2mpg at best (you will get better economy in most cases)

your motor will burn 0.4 # per hp per hour. so if you only need 10hp to get you to where you are going, you would burn 1.6 gallons per hour. however if you need all 165hp you will be burning 10.5 gallons per hour

 

[Watermann]

Weight has a huge impact on fuel consumption and 100 gallons of gas is 630 Lbs. I think you might be asking too much of a 21' boat. It would be more like a fuel tanker in order to have that range rather than a day cruiser.

 

[list249]

I should have said its aluminum, that being said,That is an outrageous amount of fuel, this boat weighs 1640lbs, it is very light. Im talking at an economy cruise, not WOT. Im looking at a pdf brochure from Donzi that claims 192 mile range from the 210 XL Medallon(3500+lbs) with 50 gallons of fuel at cruise. Am i missing something here?

 

[Watermann]

Yeah we know what a SC Chief is :lol:

With my 18' Chief's 205 HP V6 I've made 100 to 120 mile cruises with my 30 gal tank and had fuel to spare but there's no way to tell for sure how yours will do, so many variables.

 

[Scott Danforth]

if the donzi idled most of the time it may get 192 miles on 50 gallons as an average. however running with the wind and with the current you may see that type of burn rate.

however have the wind change to a 20mph head wind while going against the current and your fuel burn instantly triples to stay on plane. put the same donzi in 7' rollers against the 30 mph wind during a small craft advisory when you are on and off the throttle to make safe harbor and you can burn up 20 gallons of fuel in about a half hour and only get 2 miles

BSFC is set by motor type and architecture. how much power do you need to get your boat to the speed you need in the conditions you will encounter?....... that determines how much fuel you burn. your BSFC is about 0.4# of fuel per hp per hour.

 

[cj8mule]

My real world experience of a 1974 21' chieftain 165Mercruiser..... 2 each 18 gallon tanks. I would get anywhere from 4 to 6 nmpg in 1' to 2' Chesapeake Bay chop. (4nmpg = WOT.... 6nmpg = 2700 -> 3200 rpm)

It sounds like you need a 50 to 60 gallon tank. Or better yet, a reasonable sized tank most days and a collapsible fuel bladder for the longer trips.

--dave