Robillard
New Member
For a 1998 Sundancer 330 with twin Merc 7.4l MPI V-drives, anyone know what kind of fuel consumption I should expect at various RPMs? She cruises at about 3200 (23kts) and WOT at about 4200-4300 (30+kts). Thanks in advance!
Fuel consumption twin Merc 7.4l MPI v-drives?
- Thread starter Robillard
- Start date
Xplicitlnck
Well-Known Member
I was told about 30gph at cruise. Go to boattest.com there pretty good
ippa2
New Member
I have FloScans installed and at 3200 and 22 kts I'm burning 28-30 an hour. At 3000 rpms I can still cruise at 18-19 kts and burn 24gph. At both speeds I'm getting about .87 miles per gallon.
VinceR
Member
SEA RAY 340
2001
TWIN 454 MPI
FuelFlows by computer connected to engines.
RANGEIS 215 GALLONS
RPM MPH GPH MPG RANGE
700 3.9 2.0 1.95 419
1000 6.0 3.6 1.66 358
1200 6.8 4.4 1.55 333
1500 7.9 7.0 1.13 242
2000 12.4
2500 18.6
3000 16.9 24.0 .70 150
3200 20.5 26.6 .77 164
3400 24.1 30.6 .79 168
3500 25.0 31.0 .80 172
3600 26.4 33.4 .79 170
3800 28.0 34.8 .80 172
4000 29.5 38.0 .77 164
4300 32.6 47.6 .68 147
Robillard
New Member
Thanks, all! This is mostly in line with what I was expecting.
Thanks for the details, super cool!
Interesting. At 3300 rpm I'm at 22kts, which is 25 mph; and at 4300 rpm (WOT) I'm doing 32 kts (not mph), which is more like 37 mph. Were those speeds really in mph or kts? If really mph, I wonder what accounts for the difference? Is the 2001 340 DA much heavier? Do you have a dinghy on the back? Against a heavy current/wind, or relatively calm? Just curious.
My apologies. It was not at all clear to me which forum was appropriate for this question.
Thanks for the details, super cool!
Interesting. At 3300 rpm I'm at 22kts, which is 25 mph; and at 4300 rpm (WOT) I'm doing 32 kts (not mph), which is more like 37 mph. Were those speeds really in mph or kts? If really mph, I wonder what accounts for the difference? Is the 2001 340 DA much heavier? Do you have a dinghy on the back? Against a heavy current/wind, or relatively calm? Just curious.
My apologies. It was not at all clear to me which forum was appropriate for this question.
RollerCoastr
Well-Known Member
- Nov 15, 2007
- 3,884
- Boat Info
- 1997 400DA
340HP 7.4 Mercruiser Bluewaters
Garmin 741, 742, 8212, 24HD, Intellian I2
- Engines
- 1999 280BR
Twin 250HP Merc 350 Alpha Ones
Vince, your figures also struck me as less-than-optimal. Clean bottom and running gear? Any excess weight? Engines tuned, possibly under-propped?
VinceR
Member
Rollercoastr
We all normally operate with less than optimal conditions. Performance will change when operating with or against currents and wind different degrees of bottom and prop conditions.
I may not have had a very clean bottom. Full fuel and three on board almost full water. When fuel gets to 1/2 tanks (full tanks are 1350 pounds) you get about 8% or 9% better fuel mileage. More weight less performance. Tabs full down when running hard. I either cruise at 1200 rpm "cocktail speed" or 3500 rpm "get there speed". We have had one cruise at 829 miles one way. We have put over 425 hours on out boat since we bought it almost 5 years ago. The fuel chart I offered will be close to what you may expect loaded.
Remember fouled props are worse than a fouled bottom. But together they will devastate your fuel economy.
We all normally operate with less than optimal conditions. Performance will change when operating with or against currents and wind different degrees of bottom and prop conditions.
I may not have had a very clean bottom. Full fuel and three on board almost full water. When fuel gets to 1/2 tanks (full tanks are 1350 pounds) you get about 8% or 9% better fuel mileage. More weight less performance. Tabs full down when running hard. I either cruise at 1200 rpm "cocktail speed" or 3500 rpm "get there speed". We have had one cruise at 829 miles one way. We have put over 425 hours on out boat since we bought it almost 5 years ago. The fuel chart I offered will be close to what you may expect loaded.
Remember fouled props are worse than a fouled bottom. But together they will devastate your fuel economy.
VinceR
Member
Miles in the chart are "miles" not "knots"
RollerCoastr
Well-Known Member
- Nov 15, 2007
- 3,884
- Boat Info
- 1997 400DA
340HP 7.4 Mercruiser Bluewaters
Garmin 741, 742, 8212, 24HD, Intellian I2
- Engines
- 1999 280BR
Twin 250HP Merc 350 Alpha Ones
Vince, I was referring to the condition of your boat: by those figures, it's not performing to it's potential. I had a 330DA many years ago. I didn't have fuel meters, but my manual calculations put the consumption closer to Robillards. I also had similar speeds to his - considerably faster than your 340.
For perspective, if I set the engines in my 400DA at 3500, I would overtake you while not burning much more fuel! (35 GPH, 26 sMPH)
I'm also surprised that you would fully-deploy your tabs while "running hard". Why do you do that?
For perspective, if I set the engines in my 400DA at 3500, I would overtake you while not burning much more fuel! (35 GPH, 26 sMPH)
I'm also surprised that you would fully-deploy your tabs while "running hard". Why do you do that?
VinceR
Member
Trim tabs are set to keep the bow set where it should be and to get the best fuel mileage. Again, weight and hull and prop conditions have a great effect on performance. The degree of engine tune will aslo effect the performance. The chart I offer is what happened that day at that weight. Now we dry store the boat. The props and bottom are always clean. If I cared to run another test I may get different numbers.
On our 829 mile cruise we ran the engines 49.5 hours and burned 1125 gallons.
Average of 16.75 mph at 22.72 gph. I did not keep up with generator time. I would estimate 30 hours max.
100 miles up the Atchafalaya River against a 5 mph current and another up thr Red Rive River with a 2 mph current for about 200 miles
On our 829 mile cruise we ran the engines 49.5 hours and burned 1125 gallons.
Average of 16.75 mph at 22.72 gph. I did not keep up with generator time. I would estimate 30 hours max.
100 miles up the Atchafalaya River against a 5 mph current and another up thr Red Rive River with a 2 mph current for about 200 miles