54 motor yacht

[Boatsb]

Hull speed is hull speed

Theres no changing the lenght of the waterline with beam. Beam will contribute a small factor to the hulls efficiently but at hull speed it's not a huge factor on smaller vessels.

 

[Freeebird]

It is nice for some folks to show them selves off well.
For better or even to embarrass them self,, well.
It is obvious that you have embarrassed your self with this comment.

Yes, hull speed calculations are based on beam dimensions and further, where the widest part of the beam is is relation to the wet LOA or water line lenght.
Every inch of beam makes a difference in hull drag.
Every bit of hull drag makes a difference in propeller load, horsepower required to move the hull at a stated speed. and the amount of fuel required to produce required horsepower at the same stated speed.

Every inch of wet surface matters including the density of the water against the surface. More drag at 4 feet vs at 1 foot for similar square inches.

FI

* themselves

I don’t mind that you and Pascal have embarrassed yourselves. The idea that larger engines have no effect on fuel economy is absurd. Drop the same power in a 54MY and 53MY and fuel usage will be very close to the same at hull speed. That’s what we were talking about, wasn’t it?

 

[Freeebird]

Maybe that’s why hull speed calculations are never accurate when checked with accurate fuel flow meters? They are just a rough approximation due to factors like beam, draft and wetted surface area among others.

Fuel flow meters calculate/confirm hull speed?

Hull speed won’t be the most economical speed to run, it’s just the maximum speed you can run without requiring more power which relates to more fuel.

Can we talk about rocket science now?

 

[jim rosenthal]

Bird, pay attention to your driving. You ARE driving, aren't you?

 

[Freeebird]

Bird, pay attention to your driving. You ARE driving, aren't you?

Dave and Otto are driving at the moment.

 

[Freeebird]

The 60MY at hull speed of 10 knots with the same engines as the OP. Just imagine how much less fuel we would be burning if our beam were the same as his.

 

[Pascal]

Let me try this one last time.

8V71 performance data
http://powerforce.com/PDFs/2Cycle_Engines/DS_PF8V71T.pdf
12v71

http://www.powerforce.com/PDFs/2Cycle_Engines/DS_PF12V71T.pdf

Look at the bottom curve, the fuel per HP per hour... at the same RPM the 8v71 and 12v71 requires the same amount of fuel per horsepower. Ex 1300rpm both use 0.4 lbs an hour per BHP. Clearly engine size has no effect on fuel burn if producing the same horsepower.

 

[Freeebird]

Let me try this one last time.

8V71 performance data
http://powerforce.com/PDFs/2Cycle_Engines/DS_PF8V71T.pdf
12v71

http://www.powerforce.com/PDFs/2Cycle_Engines/DS_PF12V71T.pdf

Look at the bottom curve, the fuel per HP per hour... at the same RPM the 8v71 and 12v71 requires the same amount of fuel per horsepower. Ex 1300rpm both use 0.4 lbs an hour per BHP. Clearly engine size has no effect on fuel burn if producing the same horsepower.

Let ME try this again. OP is running 8V92 700HP engines. You said the engines were not the primary factor in a 54 vs 53 fuel consumption and said the extra beam was the culprit.

Yes, if the 53 and 54 were equipped with the same power, the 53 would get better fuel economy, for all the reasons Captain Obvious pontificated. Even then, I’m guessing the difference between the two would be marginal. I’m sure I don’t have to remind you that Hatteras made the 1510’s because they were located inland. You can argue the point either way, but the 54 was a long awaited improvement over the classic, albeit dated 53.

 

[Pascal]

Obviously more beam is an improvement... that s not the point. We re discussing why the wider beam boats burn more fuel at hull speed. You claimed it was due to the larger engines. The fuel burn curves posted above shows engine size is irrelevant as they burn the same fuel per hp. The difference comes from the wider beam

 

[Freeebird]

Post up some GPH numbers from DD on those 8V92’s vs the highest HP 8V71’s available in a 53, then we’ll see.

 

[Pascal]

Post up some GPH numbers from DD on those 8V92’s vs the highest HP 8V71’s available in a 53, then we’ll see.

http://www.powerforce.com/PDFs/2Cycle_Engines/DS_PF8V92T.pdf

 

[Boatsb]

Ive never seen a marine 8v92t at 430 hp.

I've seen 6v92t at 550 and higher hp. 8v92 over 700. I guess the fuel curve must be the same per hp on a non intercooled truck engine vs a twin turbo intercooled marine engine.

Remember if you look hard enough on the internet you will find the backup for the opinions you want weather theye right or not.

 

[Freeebird]

http://www.powerforce.com/PDFs/2Cycle_Engines/DS_PF8V92T.pdf

Well, those aren’t the 720HP variations, and without 871TI specs, it really doesn’t serve any purpose in this conversation.

 

[Pascal]

Doesn’t matter if the engines are industrial or marine. A larger Detroit isn’t going to start burning more fuel per hp because it s in a boat vs in a truck or attached to a generator

I know these are industrial curves but I wasn’t going to waste any extr time looking for marine curves

So keep thing Beam doesn’t affect fuel burn if you wish...

 

[Freeebird]

You just don’t get it, but it’s okay. Just for giggles, what power in a 53 were you referencing as a basis for comparison?

 

[Boatsb]

You know it's time to quit wrestling with the pig when the pig likes it. Bird needs to move boats that dont have wide beams and strut to comply as a good bird should.


One of my bubba friends teecheched me dat.


By the way incant believe you ran inside from Eliot. How could you.

 

[Freeebird]

The extra beam width makes the boat sit higher in the water and lessens the draft.

 

[oscarvan]

The extra beam width makes the boat sit higher in the water and lessens the draft.

You're just messing with us right?

 

[racclarkson@gmail.com]

You're just messing with us right?

More air inside.