Fuel burn in a 1976 64’ motor yacht

[JessStanley]

Fuel burn in a 1976 64’ motor yacht

Debating between boats and am also considering a 65’ trawler. The Hatteras is a 64’ with a cockpit extension and has twin 12v 71ti’s Any idea of what fuel burn would be at say 10mph? Would like to use the boat for some decent sized trips next year and just want to know roughly what everything is going to run.

 

[jim rosenthal]

Re: Fuel burn in a 1976 64’ motor yacht

I'm going to guess 2 gal/nautical mile with engines and genset on- now, we'll see how much the more experienced folks say..

 

[Freestyle]

Re: Fuel burn in a 1976 64’ motor yacht

From experience and listening to other owners, you can operate a 64, or most Hatteras motor yachts, at around 1 gallon per nm operating around hull speed which is theoretically about 10 knots for a 64 but your flowscans will say 8.4 knots is your sweet spot..

Life in the slow lane works well for these old boats.

Bruce

Freestyle
1986 62 CPMY (54MY with ext)
Tampa

 

[JessStanley]

Re: Fuel burn in a 1976 64’ motor yacht

From experience and listening to other owners, you can operate a 64, or most Hatteras motor yachts, at around 1 gallon per nm operating around hull speed which is theoretically about 10 knots for a 64 but your flowscans will say 8.4 knots is your sweet spot..

Life in the slow lane works well for these old boats.

Bruce

Freestyle
1986 62 CPMY (54MY with ext)
Tampa

Beautiful, thats about what I was hoping it would be roughly and close enough to the trawler to not be much of a determining factor

Thanks

 

[RonNP]

Re: Fuel burn in a 1976 64’ motor yacht

My 63 CPMY would get an average of 0.7 mpg at 10 kts with one generator running. Going downhill closer to 0.9 mpg

 

[Pascal]

Re: Fuel burn in a 1976 64’ motor yacht

A 64 should burn about 10/12 gph at 9.5 to 10kts. Beam affects fuel burn too at hull speed.

You could potentially save even more by slowing down a knot but the engines may run too cold.

Go just one knot above hull speed and your fuel burn will jump 60 to 70%

Hull speed is usually define as the sq root of waterline length x 1.33

 

[Sadey]

Re: Fuel burn in a 1976 64’ motor yacht

60MY with 892’s at 1350rpms gives me 10.2kts. 10.3kts is hull speed for my approx LOA. I plan 14GPH with gen running. Gives me a 1.5/hour reserve. I run the motors up to 1900rpms for 10 minutes every few hours.
I use the fuel per hour because I run the same exact rpm’s every time and the motors don’t know how far they’ve traveled but I enter the hours run every trip in my log book.
Hope this helps.

 

[JessStanley]

Re: Fuel burn in a 1976 64’ motor yacht

60MY with 892’s at 1350rpms gives me 10.2kts. 10.3kts is hull speed for my approx LOA. I plan 14GPH with gen running. Gives me a 1.5/hour reserve. I run the motors up to 1900rpms for 10 minutes every few hours.
I use the fuel per hour because I run the same exact rpm’s every time and the motors don’t know how far they’ve traveled but I enter the hours run every trip in my log book.
Hope this helps.

Thank you, helps a ton and isn't quite as bad as thought possible

 

[JessStanley]

Re: Fuel burn in a 1976 64’ motor yacht

A 64 should burn about 10/12 gph at 9.5 to 10kts. Beam affects fuel burn too at hull speed.

You could potentially save even more by slowing down a knot but the engines may run too cold.

Go just one knot above hull speed and your fuel burn will jump 60 to 70%

Hull speed is usually define as the sq root of waterline length x 1.33

Thanks, did the math and its saying just over 11kts, not bad, I'm not in a rush if I've got the house and eveveryone with