MAN i6

[bpgt3]

Hi all. I did read a thread from 2011 but wondering if maybe things have changed.

I looking to run from SF to Hilo next year with a 58 Fleming. It has twin 800hp MAN i6's. For that range I need to run for an extended period of time at around 7knots. Is this possible without doing damage to the engines?
I'm sure people will have opinions about the feasibility of this run but i'm just interested in the effect on the engines. Would running them at low rpms for a couple weeks straight do permanent damage?
Would it be wise to take on fuel in bladders to be able to occasionally run them up in rpm? How often would i need to do this and for how long?

Thank you For your replies.

 

[Comodave]

I would ask Mann since they will have the most information. And information that is accurate. Or maybe ask Fleming as they seem to be very responsive to their owners.

 

[Gdavid]

I would not be concerned about under loading as long as the engines are able to reach an acceptable operating temperature. Being common rail engines, they are less susceptible to incomplete fuel burn at lower speeds compared to mechanically controlled engines.

That said, I am a stranger on the internet, not familiar with the boat and not willing to offer you any form of financial assurance that I am right. Are you already familiar with the boat and how the engines respond to extended operation at relatively low speed? If the boat is new to you and/or this is a delivery, I would be more concerned about getting familiar with the entire boat and it's systems in advance of this trip.

 

[Insequent]

I agrre that checking with MAN is best. But as I recall for my John Deere's the dealer advised that provided I completed the run-in correctly, then I could operate at low rpm after that if I wanted too. Their run-in procedure was a special oil, and varying power frequently but typically 60-80% load for that first 100 hours.

 

[ranger58sb]

Hi all. I did read a thread from 2011 but wondering if maybe things have changed.

I looking to run from SF to Hilo next year with a 58 Fleming. It has twin 800hp MAN i6's. For that range I need to run for an extended period of time at around 7knots. Is this possible without doing damage to the engines?
I'm sure people will have opinions about the feasibility of this run but i'm just interested in the effect on the engines. Would running them at low rpms for a couple weeks straight do permanent damage?
Would it be wise to take on fuel in bladders to be able to occasionally run them up in rpm? How often would i need to do this and for how long?

You could ask your current MAN tech.

You could ask Performance Diesel in Houston, the south and east coast distributor for MAN. (Although I see their website is wonky just now, probably have to call.) Might be a separate west coast distributor you could check with, too.

You could ask on boatdiesel.com.

You could ask Burr Yacht Sales guys, Fleming's east coast outlet. (Or Fleming's west coast folks, whoever they are.)

And I've read that electronic common rail diesels are much better suited to long runs at low RPM as long as you first get temps up in the proper operating range... compared to older mechanical diesels. (And then there's the older advise about occasionally running up to higher RPM, which may not actually use all the much more fuel, depending on frequency and duration.)

FWIW, we have a pair of V8-CRMs (D2848LE423), apparently MAN's first foray into electronic common rail diesels, and we run at 8 to 8.5 kts a lot... usually somewhere in the neighborhood of 800-1000 RPM depending on tide/current and wind. No apparent ill effects after our 400 hours or so... with about 2000 total hours on the engines...

I6-800s would be the cat's meow in our boat, but they're newer than our was built.

-Chris

 

[bpgt3]

Thank you all for your replies. I appreciate your time.
I will post in the marine diesel forum. I actually didn't even know that existed....and i searched for something like it.

 

[Ken E.]

Tony Fleming has MAN's in his personal Fleming and has taken it on long-range cruises. If you pose this question to his office in CA, I bet he could tell you a lot. I believe Tony's daughter runs the office and can connect you with him.

 

[NWboater2]

happy GB owner here with no knowledge of that engine. but Fleming 58 is my absolute dreamboat. My bet (but not my advice!) is there is no way Fleming would build a boat that was otherwise well suited to go to HI with engines that really shouldn’t do it. I would actually be disappointed if they did.
Its worth a poke around any of several threads here or especially on sailing anarchy about a recent similar trip by a delivery skipper named Ray McCormack, in a sunseeker 54. Same concerns about impact of low load on big diesels …..lots of other concerns too, none of which would apply to you! Good luck!

 

[rslifkin]

Its worth a poke around any of several threads here or especially on sailing anarchy about a recent similar trip by a delivery skipper named Ray McCormack, in a sunseeker 54. Same concerns about impact of low load on big diesels …..lots of other concerns too, none of which would apply to you! Good luck!

Good point, as that questionable endeavor did involve a pair of pretty much the same engines I think. They were certainly MANs of some kind. And apparently they checked with MAN before departure and got the OK to run them near idle for the whole trip.

 

[bpgt3]

happy GB owner here with no knowledge of that engine. but Fleming 58 is my absolute dreamboat. My bet (but not my advice!) is there is no way Fleming would build a boat that was otherwise well suited to go to HI with engines that really shouldn’t do it. I would actually be disappointed if they did.
Its worth a poke around any of several threads here or especially on sailing anarchy about a recent similar trip by a delivery skipper named Ray McCormack, in a sunseeker 54. Same concerns about impact of low load on big diesels …..lots of other concerns too, none of which would apply to you! Good luck!

Thank you very much for your input. I will be checking on that thread. Am i thinking of the right Captain who ran aground a few times or is he a different captain?

 

[NWboater2]

That’s the one. Sunk one too

 

[Barstock]

There is no problem with running diesel engines at low load for long periods, all modern electronic engines no longer suffer from overfuelling or cylinder cooling at low speed.
You can also run on one engine which would raise the load slightly on the operating engine. Just trail the other engine, the Fleming 58 has Seatorque shafting in them so can be trailed indefinately without problems. Similarly the transmission on that side would be able to handle light load trailing without overheating. 6 hours a side and you will save your engines by halving the engine hours as well as reducing overall fuel consumption by approximately 15% to 20%.

 

[Cold Duck]

Slightly off topic but, make sure you have slips reserved for the different Islands you are visiting. It is very difficult to find a slip for a 58' in the Islands. There's a 15 year waiting list at Kona and anchoring during winter months (Oct-May) is rolly polly at best. Better anchorages off lee side of Maui Just a FWIW input.

 

[BluewaterN47]

Zero experience with Manns, but long experience with a Lugger 668T in my Nordhavn 47. When we were making long passages, we generally cruised at 7 knots. but on the advice of Bob Senter, a longtime professional diesel engineer and teacher of seminars for Lugger dealers and Nordhavn owners, we made it a point to run the main engine up to full RPMs for about 15 minutes at least once a day. On our Atlantic crossing we did that every day at noon. A friend who had twin Cat 3208TAs in his Grand Banks 46 followed the same protocol and never had significant issues.

But I second the recommendation that you touch base with Mann. Nothing like talking to the guys who designed and built the engine and have maintained thousands of them!

Milt Baker, former N4732 Bluewater

 

[Cold Duck]

There is no problem with running diesel engines at low load for long periods, all modern electronic engines no longer suffer from overfuelling or cylinder cooling at low speed.
You can also run on one engine which would raise the load slightly on the operating engine. Just trail the other engine, the Fleming 58 has Seatorque shafting in them so can be trailed indefinately without problems. Similarly the transmission on that side would be able to handle light load trailing without overheating. 6 hours a side and you will save your engines by halving the engine hours as well as reducing overall fuel consumption by approximately 15% to 20%.

Good idea, we use to troll for salmon on one engine, then the other. Here we just couldn't get the boat slow enuff with both just idling.

 

[ranger58sb]

long experience with a Lugger 668T in my Nordhavn 47. When we were making long passages, we generally cruised at 7 knots. but on the advice of Bob Senter, a longtime professional diesel engineer and teacher of seminars for Lugger dealers and Nordhavn owners, we made it a point to run the main engine up to full RPMs for about 15 minutes at least once a day. On our Atlantic crossing we did that every day at noon. A friend who had twin Cat 3208TAs in his Grand Banks 46 followed the same protocol and never had significant issues.

I know those Cats aren't electronic engines; was your Lugger electronic or mechanical?

-Chris