N6833 Delivery
- Thread starter Jon H
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The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
If you have answers, please help by responding to the unanswered posts.
twistedtree
Guru
No, not me. I'm still waiting. But it's a good friend of mine, and I've been on the boat many times. He's the guy who inspired me to go with a Scania main engine.
mvweebles
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- 1970 Willard 36 Trawler
Interesting. Care to share your thoughts on Scania? Honestly, I know nothing about them except OTR. Didn't know there was a Marinized version. Inquiring minds would like to know....
Peter
twistedtree
Guru
Here's a blog article on the engines considered, and factors that led to the Scania.
Adventures of Tanglewood: Mirror, Mirror, on the Wall, What's the Fairest Engine of All
It's not a choice without risk. I have a lot of confidence in the product, but support in North America is thin. I typically do all my own work, but if I have warranty issues I'll need to track someone down. It's not like a Cat, Cummins, or Deere where you can throw a stick and hit a trained tech.
mvweebles
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As usual, great blog post. I learned a lot - Thanks.
For what it's worth, the factory Cummins techs I've seen recently are skilled at replacing parts into the find the right one to solve whatever the problem is. It's an expensive troubleshooting approach so not sure local factory support is necessarily helpful
Peter
twistedtree
Guru
And that’s why I do pretty much all of my own work. It’s rare that anyone diagnoses a problem. In stead they just guess and replace parts until the problem goes away - or doesn’t.....
O C Diver
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Your blog article on engine selection was an interesting read. I'm curious if the heat rejection into the engine room numbers were absolutes or a graph. My JD 4045 cruises at 2 GPH around 1,500 RPM. It doesn't get hot enough to cook the paint off anywhere on the engine. As a mental exercise I curious what the curve of the heat into the engine room looks like. If it was a graph for the JD, I'd really like to see it.
Ted
twistedtree
Guru
Most of the data sheets that I've seen, Deere included, just give one max number for full power operation. Scania gives several data points, so a crude graph. Here are the numbers at RPM points, and kw of heat rejection to ambient.
1200 rpm - 11kw
1500 rpm - 13kw
1700 rpm - 14kw
1800 rpm - 14kw
This is for the marine engine, so I think that's with a prop load at those RPMs, but it's not clearly stated.
My thinking has been that since most of the block that's radiating heat stays at a pretty constant temp regardless of load, that heat rejection wouldn't vary hugely with load. Some engine parts do heat up more under load, so I would expect some change, but not linear with load. I think these numbers confirm that, but it's hard to tell for sure.
mvweebles
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I have to say, posts like this and MV Dirona never cease to amaze me. You Nordhavn guys worry about stuff I've never even thought of. I guess ignorance is bliss.
Someday if I hit the lottery, I'm buying a boat from one of you guys. I don't care what brand. I want the boat one of you guys owned and agonized over.
Thanks for sharing. I really do enjoy this level of detail
Peter
Someday if I hit the lottery, I'm buying a boat from one of you guys. I don't care what brand. I want the boat one of you guys owned and agonized over.
Thanks for sharing. I really do enjoy this level of detail
Peter
O C Diver
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Those numbers don't surprise me that much for the Scania engine as the peak output rejection numbers are so low. I would guess there's a much bigger spread for the JD engine as their peak rejection numbers are so high. You can't have high rejection numbers and no cooling system rejection with wet cylinder liners at low fuel burn.
Ted
twistedtree
Guru
They also all provide numbers for heat rejected to the cooling system, both for the engine, and for the after cooler. Most also provide rejection out the exhaust, and if not, it can be calculated based on flow and temperature. All of it has to sum up. Fuel energy in, crankshaft power and heat out.
Anyone designing an engine into an application needs this info to size radiators, keep coolers, heat exchangers, etc. Plus room ventilation for generator shacks, enclosures, and ...... boat engine rooms. All the engine manufacturers require an application review in order to activate the warranty where it's verified that all the specs are met for the engine installation.
twistedtree
Guru
Pete Meisinger
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Me? I check the oil, start the engine, look for cooling water out the back and start my adventure, watch the gauges throughout the day.
Next day, repeat
I have no understanding of, nor do I care to learn about rejected heat, KW per rpm, a service manual printed in a foreign language or sourcing parts from Europe.
I'm just a small town boy enjoying my boat.
pete
Next day, repeat
I have no understanding of, nor do I care to learn about rejected heat, KW per rpm, a service manual printed in a foreign language or sourcing parts from Europe.
I'm just a small town boy enjoying my boat.
pete
Donsan
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For coastal cruisers, it really isn't an issue. You will rarely run your engine more than 8 hours per day if that. But if you are crossing oceans, it can be an issue specially in the tropics.
O C Diver
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Planning on adding / modifying the ventilation next time I'm in the boatyard. It's good now, but might do a trip to the Bahamas in the future and it certainly wouldn't hurt to have more. Would be nice to have an idea of what I'm trying to overcome.
Ted
O C Diver
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Where you boat, engine room heat really isn't going to be a factor. We all focus on things that are important to us. You probably have given more thought to winterizing your boat, I just keep using mine.
Ted
twistedtree
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mvweebles
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TT - what's your take on Tier 3 and common rail? Given you're prepping for globe trotting, what are your thoughts on vulnerabilities related to electronic controls, and of course Scania? I know it's no longer an option, but would you sacrifice common rail efficiency for relative bullet proof of a tier 2? What's your best thinking?
twistedtree
Guru
Well, my last two Tier II engines were common rail, and actually the Scania isn't. It's unit injectors. Now that's a bit of a nit because it's still high pressure, computer controlled injection, except the high pressurization happens in each unit injector at time of injection rather than all the time throughout the system via a central high pressure pump. The Deere 13 liter and it's predecessor 12L are unit injector, as are the Detroit/MTU Series 60 engines. The approach goes back to the 2 stroke Detroits, and perhaps further. Others here have a much broader knowledge of diesels than I do and can probably add a bunch.
But to your question, I have no issue with electronic controlled engines, and in many ways I refer them. Yes, they can break, but so can mechanical engines. I haven't seen any statistic, but when I look at stories of engines being repaired for this, that, or the other, it always seems to be some sort of mechanical thing that has worn out or broken. With few exceptions, mechanical parts wear, and electronics don't. But electronics are susceptible to electrical spikes like lightening. Lots of protection is built in, but they aren't completely immune. But just look at all the road vehicles out there and their reliability. Every one is computer controlled. Actually, controlled by dozens of computers. And vehicles are more reliable today than they have ever been. New things go through teething pains, but sorted out, and that happen in road vehicles years before the same technology hits marine use.
I think a lot people's fear about electronic engines is simple because they don't understand them, or feel they can better understand a mechanical engine. We all fear what we don't understand more than what we do understand, or think we understand. I'm an electronics guy, so feel comfortable about their reliability. That doesn't mean I can take an ECU apart and fix it, but neither can I tear apart an injection pump and repair it.
And as you point out, there is no choice. So even if I didn't like it. all I can do is anticipate failures and be prepared to deal with them, just like with any other part of the boat.
Jon H
Senior Member
One of our pilot boats had an electrical gremlin that would throw various
codes (none of which prevented the engine from running) which were eventually traced to a faulty wiring harness.
Once a new harness was installed problem solved, everything has been fine
since then. Takeaway is if you get past the first few hundred hours you'll probably be fine.
FWIW engines are Cummins QSK-38's that run about 3,400 hours/year.
codes (none of which prevented the engine from running) which were eventually traced to a faulty wiring harness.
Once a new harness was installed problem solved, everything has been fine
since then. Takeaway is if you get past the first few hundred hours you'll probably be fine.
FWIW engines are Cummins QSK-38's that run about 3,400 hours/year.
mvweebles
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Thanks. Figured you would have a decent perspective even though it's settled science due to EPA guidelines. I count myself as one of the Neanderthals who prefers mechanical engines despite the attractive improvement in efficiency. I can usually figure stuff out, but electrical and electronic is definitely not my strongest suit. I'd worry less about the dreaded ECU failure and more about some small control wire that goes to an interlock of some sort such as a fire suppression system. Even if I knew to look for it, I'd never find it. Unlike OTR vehicles, boats are one-off with a crazy amount of owner-specified bolt on goodies (such as the aforementioned fire suppression system) that may have intended or unintended interdependence with the engine (such as aforementioned.....). I've been around the block a bit, but in all candor, haven't had too many engine issues. I've seen a couple ECUs replaced, but the real fault ended up being something else (such as the aforementioned....). So I suppose you're right. Engine itself is great. But the install and config may not be.
But thanks. Just curious how you think through these things. I'm awestruck by you old time Nordhavn folks.
But thanks. Just curious how you think through these things. I'm awestruck by you old time Nordhavn folks.
