How much smoke is too much?

[FF]

The data sheets referred to above give me too high a number based on what my usage estimates are. Maybe I am reading them wrong. Anyone with experience or sound theory here? Chart reads 7 gph? and usage feels more like mid-high 3 ish. __________________

The usual data sheet suggests the fuel burn at that RPM if taking the max HP available at that RPM.

7 GPH would suggest 125 or so HP could be had there , 3GPH would suggest 50 -55Hp is being used .

 

[bayview]

Yes use the prop demand curve not the max power curve.

 

[hollywood8118]

I love your Ocean Alexander 40. We looked at one, the one that got away, when we were just starting to look at boats, but not ready to pull the trigger yet.

I really like the layout of the O.A. Europa.. has a lot of livability in 40'. the only down side is the low clearance E.R. The upside is that I can get around all sides of both the main and the Genset.. albeit on ones knees
HOLLYWOOD

 

[klee wyck]

The whole engine thing is pretty inspiring when you think about it. The engineering, materials, and assembly are a wonder. I worry about my 5000 hour green monster a little in the boat but wonder why I do. Boat diesel engines get such good care on average and run such low hours on most boats and in pretty decent conditions. I am a pretty part time boater but my full time day job requires me to own nearly one hundred engines and they work in tougher conditions and get inferior care to most boat engines. They are Cats and Cummins, Deere, Mann, MBE, Detroit, Perkins, Volvo, and more. Several have turned in over 20K hours and I have a little Perkins that has done over 25000 on nothing but filters. I figure it has done over 3.3 billion revolutions. I've got a Cummins in a T400 that has done over 2 million miles and some fair bit of it in fields. Its a giant testimonial to these engines given how little I know about them and what tough, dusty, often overloaded conditions they work in. We are decent on lube change intervals and take no prisoners on filters, especially air, but not much beyond that.
Pretty amazing is what it is. I expect most boat engines don't get tested that much before the hull disappears from around them.
The new ones are damned tricked out and do tend to run quite a bit cleaner but I'll respect them as much as the older ones when they prove they can do the time.
Here's to engines and the engineers that design and build them......

 

[FF]

High time engines cant have spent much time just sitting.

Boat engines sit for months on end, with their exhaust open usually to sea water.

This is far harder service than running ESPECIALLY since few boat owners actually follow Da Book , and use the eng. mfg "out of service for over 30 days" procedure. (It costs money)

Lay up is usually an oil change on a cold engine then shutting it off for 6 months.

That they don't smoke like a Cho Cho train from rusty cylinders and low compression is a remarkable thing.

 

[Capt Nemo]

OK, Gotta ask. There are a few NO TURBO guys here Please tell my why.

 

[ghost]

There is nothing wrong with a turbo charger. In fact, they allow engines to run at efficiencies you can't achieve without one.

The downside is simple. More moving pieces and that eventually equates into more maintenance.

First off a turbo while a simple device by itself, creates some new issues to deal with. First off is that we place it in our exhaust flow, not a very friendly place. It gets hot, so the turbo needs cooling and that means a few more gaskets and passageways that have a high level of heating up and cooling down. Next, a turbo charger is really just an air pump. The act of compressing gas causes it to heat up, robbing you of some of that efficiency you were trying to tack on in the first place. To handle that, we add an aftercooler, which again adds more gaskets and plumbing to keep watch on. Of course as we now cool our intake airflow, we start to condense that which is in the air intake including recirculated crankcase fumes which causes a bit of oil to coat the aftercooler over time.

For a boat running at trawler speeds, which has the ability to also run faster it means that much of the time the turbo charger is essentially just along for the ride and neither really contributing, but also accumulating coke on the turbo blades and gunk in the aftercooler. So when you do throttle up, you may need to burn off some of that accumulated coking before your engine stops temporarily smoking. The only way I ever found to clean an aftercooler was to put it on a schedule to pull it off and quite literally clean it up. Many don't and just live with a reduction in performance, albeit a small one.

Its nothing you can't keep up with and in the scheme of things, is not that big of a deal. Of course if you are putting around at 8 knots all the time, one may not see the benefit and I definitely feel the freedom of neither having to keep up with those systems, but more importantly never worrying about having to plan for a failure. In that regard, it's quite a significant streamlining and simplification.

 

[Ski in NC]

I just finished cleaning the aftercooler on my Cummins 6C 450. I was pleasantly surprised on its condition. Last time cleaned was in 09 at 900hrs, this time it had about 2040hrs. No corrosion in housing or core, tubes had a little mineral buildup, fins clean with some liquid oily slime.

So aftercoolers are not all evil!! Replaced a bunch on other Cummins B and C's.

One thing I do that is different is if boat is going to be laid up for more than a week, last 5miles or so I run at low speed to get condensation in cooler to dry out. Looks like a good strategy.

The ones that had the coolers corrode were sportfish where they would come in hot to the dock, shut it down and leave it sit for a month. The condensation pooled in the bottom and on disassembly you could see the water line.. and galvanic corrosion was doing its thing.

The turbo is a non issue on these boats. At super low load, it just idles along, not doing much but spinning slow. At higher power, it in simplistic terms makes the engine "bigger", allowing it to make much more power than without.

I've only replaced a few turbos on boats over 20yrs of servicing them. Most taken out by corrosion due to crappy exhaust design, one or two actually failed due to problems with rotating hardware. Again, mostly go-fast sportfish.

So best of both worlds. At low power, the smaller engine is fairly efficient, at high power the boost allows the smaller engine to make bigger power.

Turbos also quiet the air intake and exhaust some.

Not afraid to have a turbo engine in a trawler at all. Good tech...

 

[Alaskan Sea-Duction]

Blue smoke is oil smoke. Not injectors. Smoke is caused by valves rings or turbos. First of all, there is no emission control, so they will smoke. Think dump truck, not Audi. Next, warm your engines with a load. Running them wot will clean out the soot etc so you will get more smoke, it also is an excellent way to check the entire engine, especially the cooling system. Go for the easy stuff first: change the oil and filters, change the air filters, adjust the valves and then go cruising. When the oil consumption gets excessive, overhaul time. But until it does, long time from now, just go cruising.

Agree. Blow boats call us "stink pots" for a reason. Change the oil, filters etc and run it all summer. I left Saturday and went to Kalama to fuel ($2.19 gal) and I noticed I had smoke for a while, then it leveled off after they warmed up.

Go have fun!

 

[Ski in NC]

Oily slime in exhaust does not mean there is a problem with valve seals, rings or turbo. Run a healthy engine slow and it will accumulate residue from unburnt fuel and normal amounts of oil moving by the rings, there will always be some.

So if engine smokes on power up, then cleans up afterward and is otherwise running fine and not using excess oil, it is not a problem.

 

[FF]

A turbo will add power to a small engine , so it can make more power like a bigger engine.

If your boat is a Sport Fish , usually run on the pin and you need a few extra K its a fine idea.

Most cruisers are way back on power consumption , traveling at displacement speeds , most engines are far too large , not too small.

All the bucks on a turbo, inter cooler and the added maint go to waste when the cruise RPM is so low the turbo produces no boost , its just a fancy plug in the exhaust.

 

[Ski in NC]

If engines are far too large, then yes, unnecessary. But also no harm in it being there. Many if not most modern engines come from the factory with turbos, so you are stuck with what is available.

My boat, like many others on here, is "dual purpose", capable of running well past hull speed, but also capable of good efficiency at trawler or hull speed. The turbo is a necessary part of being able to do that.

 

[twistedtree]

My turbo boosts at normal cruise speed of around 8kts. Not full boost, but it's definitely working.

 

[River Cruiser]

OK, Gotta ask. There are a few NO TURBO guys here Please tell my why.

After many years as a mechanic a turbo is a method to squeeze more power from a engine, it's also a failure point and expensive to repair. At the RPMs I normally cruise a turbo wouldn't be doing much to add power or economy to the engine and I wanted a diesel boat without a turbo. Basically a turbo to me wasn't worth the work and cost to repair if they grenade.