Fuel consumption for 43' DC (great loop and icw)

[bigmell]

Hey guys,

I did some math on fuel consumption and wanted to check with you guys to see if these were ballpark figures. I figured traveling at around 7-8 knots I would get around 1.5 miles per gallon. The tank is 375 gallons meaning at 7-8 knots I would be able to travel ~562 miles per tank. Diesel is around $3 dollars per gallon meaning it would take about $1125 dollars to fill my tank.

The ICW is around 3000 miles, so to complete 3000 miles on the ICW would be about ~6 tanks of gas costing around $6750 to complete (diesel only).

The great loop is around 6000 miles, so to complete this would be about ~12 tanks of gas costing around $13500 to complete (diesel only).

Do these numbers look about ballpark have I overlooked anything? Can anyone with this boat confirm or deny these numbers? Also any worries about height or draft? From what I understand this boat clears the 19' height and the draft isnt close to the limit.

 

[Mel Tucker]

What's your power source? My 43DC is powered by Cummins 903 T's. At 10 knots or less I figure 1 gallon per mile. I then run up to 2300 RPM (15 1/2 to 16 1/2 knots) depending upon depth of water, sea conditions and figure that at 2 gallons per mile. I just completed a 2000 mile round trip from the Pamlico River in North Carolina to Rockland, Maine and back. One leg we went 170 miles (Long Island Shelter Island to Cape May, NJ at 2300 RPM (15 kts) with seas 2-3 ft. and used 275 gallons. Sea state, depth of water, bottom maintenance, and RPM setting must always be considered. Mel Tucker

 

[Finalee]

My former 1971 43 DC with 6v92's was more like 1 nmpg at 8 knots. .50 nmpg at cruise of 18 knots.

 

[spartonboat1]

Another engine option you may have would be the 310hp J&T 6-71N's, which are quite common. Discussions here always indicate 0.7 nmpg at cruise of 12.7-13.5kts. Note that I cannot achieve more than max of 2,440 rpm, vs. rating of 2,500rpm. I cruise as 2,150-2,200rpm, as long as both engines stay below 180 degrees.

I always heard about 1.5nmpg (2.0?) at hull speed of 8.9kts; hull speed is supposed to be the best for efficiency. Maybe economy would be better at lower speeds, but 6.5-7.0kts is about as slow as I can go. The hull speed of 8.9kts may be too fast for the ICW; this I don't know.

I have also read that the fuel recommendations call for a 20% reserve; 75 gals = 20%. That results in using 300 gallons of the 375 gallon total capacity, before on reserve. So if running, until you reach the reserve, that distance would be 450nms.

I notice that when running at cruise speed that the depth of the water affects speed and economy. At or below 25' of depth seems to knock about 0.5 kts off the speed, due to the pushback from the sea bottom, as you push along.

Final remark about economy is to avoid running on a single engine, unless some type of lock can be applied to the inop shaft; otherwise damage can occur to the transmission, which is not powered.

 

[bigmell]

The engines are twin 6-71TI Detroit Diesel. I was always curious why people cruise at 12 and 13 knots. It seems like it just burns gas really fast. You will never go faster than 7-8 knots in a sailboat, and the fastest sailboats in history were the clipper ships with 5 masts. They were called clippers for clipping days off voyages and they only went 14-17 knots. Is this speed a necessity somehow or just that you guys feel 7-8 knots is too slow?

 

[Finalee]

6 knots on a sailboat is quick. 7 is flying. Generally speaking that is. When I cruised our 43, 8-10 knots was the economy zone. The higher end was running with the current. Coming from a sailing background, that was plenty quick.

 

[spartonboat1]

The engines are twin 6-71TI Detroit Diesel. I was always curious why people cruise at 12 and 13 knots. It seems like it just burns gas really fast. You will never go faster than 7-8 knots in a sailboat, and the fastest sailboats in history were the clipper ships with 5 masts. They were called clippers for clipping days off voyages and they only went 14-17 knots. Is this speed a necessity somehow or just that you guys feel 7-8 knots is too slow?

In the days of the Clipper ships, they would cruise under sails at 25-35Kts, hard as that is to believe!

 

[eze2bme]

Also don't forget the fuel used by your generator - I'd figure 1 gallon per hour if you have the Onan 7.5KW unit.

 

[Nonchalant1]

The engines are twin 6-71TI Detroit Diesel. I was always curious why people cruise at 12 and 13 knots. It seems like it just burns gas really fast. You will never go faster than 7-8 knots in a sailboat, and the fastest sailboats in history were the clipper ships with 5 masts. They were called clippers for clipping days off voyages and they only went 14-17 knots. Is this speed a necessity somehow or just that you guys feel 7-8 knots is too slow?

There are sections where you will want to go faster. We did the Great Loop in a 53MY with 8V71Ti and for longer stretches you want to arrive during daylight, like crossing the Gulf to Steinhatchee or Clearwater Beach, crossing from Naples to either Marathon or Key West, traversing Delaware Bay or Traverse Bay in Lake MIchigan, etc. PLus there will be times you just want to get there in time to make the bridge closing or in time for dinner. So count on a bunch of high speed cruise just for fun.

Here is a blog of our trip. Lots of pictures have been reduced by blogspot because it's 10 years old, but still follows the trip and interesting places to see. The best way to read in sequence is scroll to the bottom of the page and click "newer posts".
Have Fun!
Doug

 

[Walter P]

Hi Doug, Glad to see you posting from time to time. I remember your great loop trip and your 53 MY. You stayed at our club (Patten Point Yacht Club) in NJ for a couple of days and was kind enough to dive next to my boat to retrieve some railing parts that ended up in the water. Are you a land luber now or do you still cruise? I haven't done any long cruises in many years but we still have the GUPPY ('82 48 MY) at the club.

Walt