Gas consumption on a 320 DA

[melida]

$11k - $21.5K for 100 hours of boating? Yikes! :wow:]

21,5k is the expense of gas and 11k is the difference between gas and diesel expense

And to think, you guys are sitting on so much oil, you'll probably sink one day.

Thanks for the compliments

 

[trit21]

You will only burn those numbers listed above if you are loaded like they are in the test, please note:

4 people ok
1/4 fuel, no water, no water I am sure, minimum gear. Now who goes boating like that. These number from boattest are inflated because of that.

 

[Alex F]

.... Also , keep in mind 24 GPH seems a little low to me but YMMV

Tom,

You're right for the most part, but I think from just numbers point of view I'm not sure if boattest includes 10% margine. As with most tests the seas and wind conditions during the tests they do are mostly calm. I've never seen a report with 3'+ or winds stronger than 15mph. Fully loaded with gear and fuel this is not what we see during the tests either. I agree everything adds up.

Here are my exact numbers from last test (head wind ~10+mph, 1-2' chops, full fuel, full water):
- Port side 3720RPM using 12.3GPH
- Starboard side 3710RPM using 13.2GPH
This gives us 25.5GPH total.

I usually try to keep her coser to 3600RPMs and this is where the fuel burn gets closer to 24GPH. I'll try not to forget to log the numbers at 3600RPMs next time.

IMO, we shouldn't be too picky on the boattest way of testing. Their report should give us a baseline. So, if you have the same load as it says on their report and your boat has the same performance numbers that's all you need to know you're in the expected range. Everything else is errelevant, b/c we can add number of variables that may or may not apply in individual cases.

 

[pKai]

50gph seems excessive to me..... given your stated load and RPM guesstimate.

I have a 1990 310EC with twin carburated 454 inboards which is a tad bigger than your 32s and I manage .8 to 1 spmg running about 3100-ish which gets me about 21 smph. This is my "happy" cruising speed.

Now.... I can get close to 40 smph out of my boat... but those two Rochester Quadrajets punish me for the pleasure.... I can easily burn 100 gallons in 2 hours if I push it like that......

Either way, your newer/smaller MPI motors should do better than mine in all situations except maybe idle where they would be no worse than equal.

Re, the diesel commentary...... I considered a Yanmar diesel repower some time ago.... I looked at a pair of Yanmar 350hp (now have 330hp gas) with Borg trannies (my current trannies are no good with diesel -- wrong reduction) --- The whole drop-in cost was estimated to be in the low to mid $40s grand range -- very reasonable from what I'm told. It would cut my fuel consumption in half.... I did the math -- even boating about 300-400 hrs a year (im in FL) it was not worth it. Gas and Diesel are about the same (diesel now is running about .50 cents cheaper, but that fluctuates -sometimes diesel is a bit more) -- factor in the increased maintenance costs with diesel and the fact that I personally know ZERO about diesel mechanics (I do most of my own maintenance work -- up to rebuilding carbs) and it would have taken me like 15+ years to recoup my investment in the form of fuel savings.......

Maybe when one/both of my current engines crap out and I'm looking at $20k for gas vs $40k for diesel, then it may make more sense.

 

[trit21]

Tom,

You're right for the most part, but I think from just numbers point of view I'm not sure if boattest includes 10% margine. .

I do agree this is a baseline for performance, but read the fine print, range based on 90% of fuel capacity.

Again, I agree, baseline from boattest but not written in stone. Good to see everyone using their boats.

 

[barryg]

Conditions really play havoc on the numbers (as well as full fuel AND full water). The last two years I've made trips to Bimini from Fort Lauderdale and the first year the seas were rough 4 footers with some larger swells and it turned a 55 mile trip that usually takes about 2.25 hours into a 3.5 hour trip that burned up about 100 gallons. The ride back was smooth and I used 64 gallons.

 

[scooper321]

This is a ridiculously old thread, so I really shouldn't be commenting on it. But I am a 320 DA owner who has recently been wondering about his own fuel economy. My engines are smart craft capable but I don't have the gauges. So all of my fuel consumption estimates are by the seat of my pants using analog gauges. Needless to say, This thread Has been incredibly educational and helpful!

In addition, I've also started thinking about a possible move to a larger boat, something like a flybridge. And I've been going back-and-forth about whether diesel or gas made more sense. So that little subplot in this thread was also very applicable to me.

Just want to say thanks to CSR for keeping these old threads around!those of us who buy used definitely appreciate it!

 

[mnm99]

Well I have twin 496 big blocks and burn 31gph at 27mph. If your burning more than that there is a major problem. Fill up your tanks and see how much it took.