Cat 3208T Fuel consumption

[PPD]

I'm looking at a 61' trawler that is powered with twin 3208T Cats and I'm trying to get an idea of fuel burn on these motors.

The boat is a full displacement hull and displacement is around 90,000lbs.

Any input would be appreciated.

Thanks

 

[mvweebles]

I had a friend with a Cheoy Lee 55-ish trawler with a cockpit extension and 3208s. He took it to Hawaii, then on to Tahiti. I forget exactly, but I believe he averaged around 7.5 kts and 6.5 gph.

Good luck

Peter

 

[Portage_Bay]

Sign up for boatdiesel.com. Go to their calculators and enter the data in the power required calculator. You'll get HP required vs speed. Use 15 HP per gallon and you'll get a guess of fuel burn per hour. Easy to convert to MPG if you want. Then add "some". The calculater in my experience tends to be bit low. For my 3208 naturals about a gallon per hour low.

 

[tiltrider1]

I had a friend with a Cheoy Lee 55-ish trawler with a cockpit extension and 3208s. He took it to Hawaii, then on to Tahiti. I forget exactly, but I believe he averaged around 7.5 kts and 6.5 gph.

Good luck

Peter

This sounds about right to me. I like to run at 10kts, this is not an efficient speed. I am lighter at 60,000 but not FD. At this speed I burn a gallon a mile. If I back her down to 6-7kts I can get 1.5 miles to the gallon.

Now this is only true when I have a clean bottom. Dirty bottoms cost more.

 

[PPD]

So this boat that I'm looking at has the 3208s with a single turbo. Being a full displacement trawler, isn't the turbo kind of useless? Most of these that I've seen either have the 3208 naturals or 6-71 naturals.

 

[koliver]

So this boat that I'm looking at has the 3208s with a single turbo. Being a full displacement trawler, isn't the turbo kind of useless? Most of these that I've seen either have the 3208 naturals or 6-71 naturals.

Whether or not a turbo is fitted is not an issue with that or any other engine. If this is the boat you like, and you buy it, then you will see that it can be run at non-turbo speeds, and then if you want to speed up, the turbos are there to help. All they will really do for you is add efficiency at higher speeds. They don't remove efficiency at low speed.

The boats powered with engines that have no turbos are likely older boats, built when not every engine available in that size came with a turbo.

 

[mvweebles]

So this boat that I'm looking at has the 3208s with a single turbo. Being a full displacement trawler, isn't the turbo kind of useless? Most of these that I've seen either have the 3208 naturals or 6-71 naturals.

Turbos will help with efficiency. The friend I cited throttled back because he was crossing an ocean, and the distance was long enough that I have confidence in the mileage. To be honest, 7 kts in a 60-footer is pretty dang slow (160 nm/day). If range isn't an issue (and it rarely is), I'd run a boat like that at around 9-1/4 kts (220 nm/day) and expect right around 1 nmpg because of the turbos which I'd guess around 10%-15% fuel efficiency. But that's only a guess, though as a past delivery skipper, my guesses became reasonably accurate due to necessity.

Good boats. Big for their size. Getting a bit long on the tooth these days so condition is important.

Peter

 

[twistedtree]

I always figure about a NM per gallon. Then a bit better if you slow down some, and more if you want to make time. Range is probably 1.2nm/g down to .5nm/g at full speed. That's about the same for a 60' 70T boat, and a 68' 100T boat. The longer length and higher displacement mostly cancel each other out, and it's really all about how fast you want to go.

 

[DavidM]

Here is a way to figure fuel consumption for almost any boat, at hull speed:

First use the displacement to figure the hp required at hull speed. For full displacement boats, it is about 2 hp per thousand pounds, in this case it is about 180 hp. Semi displacement hulls are higher, about 3 hp per thousand pounds of displacement.

Engines vary from a low of about 14 to 20 hp per gallon per hour, but this should be an average engine as it is running at low hp output so lets use 17 which results in about 10 gph.

Displacement speed of any boat can be figured with the theoretical formula of speed in kts = 1.34*sqrt(LWL). I am guessing the LWL is about 57' so the displacement speed is 10 kts which gives 1 kt per gallon.

But that is nowhere near its most efficient speed. If you drop back to 8 kts the kpg should about double.

As noted the boatdiesel calculator will be more accurate, but the above very rough calculation is probably within 15%.

David

David

 

[PPD]

Thanks for all the feedback guys.
I’m leaning heavily towards this boat and the mains have about 4400 hours on them.

I like the idea of having a little extra with the turbos if I need it, but I plan to run the boat at around 8-9 kts

 

[bowball]

Thanks for all the feedback guys.
I’m leaning heavily towards this boat and the mains have about 4400 hours on them.

I like the idea of having a little extra with the turbos if I need it, but I plan to run the boat at around 8-9 kts

The Fleming 55 had 3208T with 435hp until the early 2000’s. With a s/d hull it was around 10gph at 10 knots. Could go 16 knots plus.

Very good engine by all accounts. Care for making sure heat exchanger etc is in shape. I think with the high HP versions (above 375) the sport fisher crowd could run into issues as they ran WOT continuously but never heard any issues from the trawler/Fleming community. Boatdiesel forum great resource.

 

[tiltrider1]

Thanks for all the feedback guys.
I’m leaning heavily towards this boat and the mains have about 4400 hours on them.

I like the idea of having a little extra with the turbos if I need it, but I plan to run the boat at around 8-9 kts

There is a big difference in fuel consumption between 8kts and 9kts. For estimating operating expenses use 1 gallon per nautical mile. For estimating range use 1 gallon per nautical mile. Once you have experience with the boat you will know what works best for you 8kts or 9kts.

 

[bowball]

There is a big difference in fuel consumption between 8kts and 9kts. For estimating operating expenses use 1 gallon per nautical mile. For estimating range use 1 gallon per nautical mile. Once you have experience with the boat you will know what works best for you 8kts or 9kts.

True. And also noise on these (and all diesels) increases substantially the faster you go, so you may find it more enjoyable going slower too.