fuel burn-4-53 RPM settings

[Al]

Finding statistical numbers which are not representative of cruising speeds so turn to the forum for information.
the subject is a twin jimmy 4-53 powered trawler with a crusining rate of 8 knots, so suspect a RPM turn of around 1800-2000 RPM, to my way of crusining the desired traveling speed is more 7 knots at a hopeful 1600 RPM range.
I have no idea if the engines are tubo or not at this point.

Thoughts?
Cheers,
Al

 

[alfamike]

GPH - MPG - fuel usage

Your fuel usage is more related to hull design & water line length & speed length ratio your specifically talking about than what engine you have.

Of course how many blade propeller & transmission ratio, etc. all come in there too.

Can you give us more info about the boat in particular, it's displacement, its over all length & water line length as well as Hull type - i.e. - Full Displacement design or semi-displacement hull design, or a planning hull design, etc.

maybe you can fill us in on more details ?

Thanks,

Alfa Mike

 

[GoneDiving]

I've found the online power calculators pretty accurate for my vessel. Then just divide by 4.7 hp/ltrs/HR to give fuel burn. USGal would be divide by 17.8.

https://vicprop.com/displacement_size_new.php

This may be a little out for 2 strokes but it's an indication. It's close for me.

 

[DavidM]

I've found the online power calculators pretty accurate for my vessel. Then just divide by 4.7 hp/ltrs/HR to give fuel burn. USGal would be divide by 17.8.

https://vicprop.com/displacement_size_new.php

This may be a little out for 2 strokes but it's an indication. It's close for me.

That is a pretty good way to figure fuel consumption, but I would use 16 hp per gph for Detroits at low rpms.

David

 

[Al]

That is a pretty good way to figure fuel consumption, but I would use 16 hp per gph for Detroits at low rpms.

David

Thanks guys, all three of you, I am shy on information as I was not relating to any specific hull configuration, was sort of looking for a back yard response from a actual 4-53 owner who had data on his/her hourly fuel burn and would include the RPM that assumed the GPH burn.
Rough I know,, I am guessing in the area of 1.5-1.75 gallons at 1800 RPM.as a ball park number.
Cheers,
Al-Ketchikan