Buying our first trawler

[jtflyn]

We are sailors moving up to a trawler and have located a great boat but I am concerned about its engines.* It is a 1981 with original Perkins turbocharged ST6.3544M engines that have almost 3000 hours on them.* I'm concerned about a possible future replacement of the turbos in view of the high hours on the engine.* Any thoughts about my concern?* If I need to replace turbos in the future can I convert to a naturally aspirated instead at less cost?**Any other advice would also be appreciated.

Jim

 

[FF]

I have seen at least one conversion where the turbo was scrapped, with no problem.

It was on a 40ish Californian , both were removed (after the failure of one cost an engine its bearings , a crank regrind and some pistons) by a Canadian that would have a heart attack at the fuel flow over displacement speeds.

Moving to a "trawler look" WHY ? ,

have you considered the other options that might work for your Desirements better?

After all a boat with twin turboes was probablt built to plane or semi plane , and is less efficient at displacement speeds as well as running the engines far below their cruise ratings.

What do you plan to DO with the boat , besides own it?

-- Edited by FF on Saturday 9th of October 2010 05:08:48 AM

 

[ralphyost]

Jim
I suggest you FIRST make a list of what you want in a boat, including first choice of engine then second, third choice of engine. You need to decide what (if any) engine is not acceptable to you.

After you have your list, go shopping and weed out those that are not acceptable enough.

If you dont understand turbos then you dont want to own one.

R.

 

[koliver]

3000 hrs on a boat that is 29 yrs old, is barely 100 hrs per year. That is average or less than average usage and is at most 1/3 of the expected life of the engines. If you put the same 100 hrs per year on those engines you will be in for a full rebuild in about 70 years. You should live that long!.
Have an engine survey done if you are concerned about them. A far greater concern that the no of hours is the number of cold starts those engines have had to endure. You won't know that, so get an oil analysis, and have somebody (engine survey) who knows what the presence of various metals in the oil really means have a look at it.
Go to Boatdiesel.com. Buy a membership. Ask away and you will get great, knowledgeable advice.

 

[FF]

"3000 hrs on a boat that is 29 yrs old, is barely 100 hrs per year. That is average or less than average usage and is at most 1/3 of the expected life of the engines. If you put the same 100 hrs per year on those engines you will be in for a full rebuild in about 70 years. You should live that long!."

This rather optomistic view requires that the engine was properly serviced each day of its life.

Most TT style boats suffer from a huge lack of maint , usually the boat is walked away from for months (years?)at a time.

For longest engine life the engine mist be "put to bed" in the off season with proper extensive and expensive work.

That so many survive with almost no PM is a tribute to the designers of these old tractor engines , and the fact that 100 hours a year of low load operation will not show up the results of poor PM .

It is also a result of operational ignorance.

While a well operating , well maintained engine might push at cruise speeds at 3GPH and the sad old neglected engine requires 4GPH for the same speed, the burn is so low that saving a GPH or a 100G a season might cost more than proper maint would have.

 

[jleonard]

I wouldn't worry so much about the turbochargers. They are easy to rebuild if you are somewhat mechanical and the kit is only about $100.
On a range 4 series Perkins I would be much more concerned with the "manicooler" (exhaust manifold and heat exchanger) and "multi-coolers" *(aftercooler, oil cooler) if so equipped.
Those parts are big bucks and "marine age" does more to them than engine hours.
The base engine is pretty stout but it's the marina add ons that will get you.
Hope this helps.

 

[Pineapple Girl]

We bought an '84 trawler ~ five weeks ago with the same engines with just under 2000s hours.* We discussed the engines at length with friends who are boaters and mechanics as well as the mechanic we hired to do the engine survey.* They checked out great and we have maintenance records from the PO, who owned the boat 18 years.* So we really weren't concerned and the boat fit what we were looking for so, we bought it.*

I love my twins.

 

[markpierce]

I'm "afraid" of turbochargers.* Seems to me they would place extra strains on the engine and shorten its life.* Is the fear rational as far as marine diesels go?

 

[sunchaser]

IMHO your fear of turbos is*misplaced but not relevant.* As previously mentioned, the HXs present a far greater set of maintenance concerns. With a new build such as you are doing, a Cummins 4B non turbo is a better choice than a revved up Yanmar with a turbo.

-- Edited by sunchaser on Monday 11th of October 2010 09:41:50 PM

 

[jtflyn]

Thanks everyone for your replies.* I became a member at Boatdiesel.com and I am studying their forum info on perkins engines.* Thanks for all your advise.* I think I'll wait until I can find a boat with a nonturbo engine so that I can run it at displacement speeds without gunking it up.* Thanks again.* I expect to be a regular follower of the Trawler Forum.

 

[koliver]

This weekend talked to a guy who has 13,000 hrs on his turbo'd 6 cly Volvo 70 series (1980s) diesel. No reason to be aftraid of turbos.

 

[Tom.B]

My only concern after having worked on gassers (in cars and not boats) my whole life is that I see performance additions like turbos and super chargers as burning the candle at both ends. Or better yet... "A light that burns twice as bright, burns half as long." Often, turbos are just added to engines that may not be beefed up in other places for the added strain forced induction systems can put on an engine. Turbo turbine fans spin up at tens of thousands of rpm and get glowing red hot. That causes all sorts of issues with breakdown of metals and bearings.

Is this an opinion based on scientific discovery? No. Would I avoid a turbo charged engine because of it? I doubt it. Partially because, at least in the case of lots of diesels, they are capable of many thousands of hours of use. Often more than we are capable of using it. Even dividing it in half would still give you an engine that will last longer than the boat it's in. Not to mention that modern engines have largely addressed many of these issues. At least I think so.

In the end, you need to decide if the performance upgrade is worth it. Everything is a compromise.

-- Edited by GonzoF1 on Tuesday 12th of October 2010 06:14:05 AM

 

[sunchaser]

In my business, earth moving and mining, turbos are not add ons. They are as essential and common as the starter motor. We are speaking here of tens of thousands of engines per year. It is not uncommon to see some larger engines with 4 turbos. This heavy equipment is not subjected to the same owner abuse as too many marine engines. Plus not having a seawater side pays great dibvidends in these non marine applications. The engines last for tens of thousands of hours and to keep the warranty active must be serviced by the book. The "old" DD 2 cyles set the bar for turbos, 50 + years ago.

 

[FF]

The "old" DD 2 cyles set the bar for turbos, 50 + years ago.

The 1936 versions of the 6-71 had a supercharger to help scavenge (push out) the exhaust gas , but it only gave a pound or two of boost at best.

Real turboes came much later.

All the heavy machinery Works for a living , works hard and often.

Pleasure "Trawlers" are run for economy , and lack pro maint.

5-1 service life difference would not be a surprise.

 

[sunchaser]

"pleasure trawlers are run for economy"**Huh??

A fully turboed Cummins made in 2010 will get about 20 - 30% better "economy" than a similar HP DD 2 stroke with about 60 -*70% the weight.

-- Edited by sunchaser on Tuesday 12th of October 2010 01:29:06 PM

 

[Steve]

These are industrial engines, as sunchaser said many thousands with turbos are built per year for construction, Agriculture and power generation applications. That said, they are additional moving parts which could fail but the benefits outweigh any disadvantage.
Steve W

 

[FF]

A fully turboed Cummins made in 2010 will get about 20 - 30% better "economy" than a similar HP DD 2 stroke with about 60 - 70% the weight.

HMMM 1936 to 2010 , and it gets 20% better fuel burn? WOW!!

That said, they are additional moving parts which could fail but the benefits outweigh any disadvantage.

THe "advantage" is higher output from a smaller motor, where most displacement "trawlers"
suffer from too large engines working not at all hard.

To get a speed boat on a plane , advantage , to get huge power into a boat that uses it to cruise , advantage, to cruise at 3 GPh , its a great advantage if the engine is 75 HP.

 

[sunchaser]

FF I never said 1936 - you did.

By the 1990s, the DD 2 strokes were pretty well optimized and at best were about 70 to 80% as fuel effecient as a well designed 4 stroke at that time. In the past 15 years, the 4 strokes have been "dialed in" so they can meet world wide emission regs at virtually any power loading - from idle to max. The DD 2 strokes could not effectively meet emission regs and were discontinued.

Five years ago when boat shopping I had the opportunity purchase a refit vessel with the last 6-71s 485 (?) hp*made and with less than 100 hours. They were found on a dealers* storage floor in crates and had been there for about 3 years. They ran well, looked wonderful, were heavy, sounded great - and slobbered oil like all good 6-71s.

The notion that a new turbo diesel "block" will not last as long as*an older NA version is pure bunk. On blocks, the warranties are even better today that 30 years ago. As always, it comes down to owner maintenance though. go by the book.

Last but not least, if you are looking for something economical, knit.

 

[Baker]

GonzoF1 wrote:

My only concern after having worked on gassers (in cars and not boats) my whole life is that I see performance additions like turbos and super chargers as burning the candle at both ends. Or better yet... "A light that burns twice as bright, burns half as long." Often, turbos are just added to engines that may not be beefed up in other places for the added strain forced induction systems can put on an engine. Turbo turbine fans spin up at tens of thousands of rpm and get glowing red hot. That causes all sorts of issues with breakdown of metals and bearings.

Is this an opinion based on scientific discovery? No. Would I avoid a turbo charged engine because of it? I doubt it. Partially because, at least in the case of lots of diesels, they are capable of many thousands of hours of use. Often more than we are capable of using it. Even dividing it in half would still give you an engine that will last longer than the boat it's in. Not to mention that modern engines have largely addressed many of these issues. At least I think so.

In the end, you need to decide if the performance upgrade is worth it. Everything is a compromise.

-- Edited by GonzoF1 on Tuesday 12th of October 2010 06:14:05 AM

Gonzo, gassers and diesels are a bit different in the diesels, by design, lend themselves to turbocharging. *In a gas engine, there are 2 main challenges with forced induction. *The strength of the rotating assemble and the ability to force air into the combustion chamber without "pre-ignition"(detonation). *The rotating assemble of a diesel engine is already very stoutly built. *ANd ignition of the fuel/air mixture is basically the same thing your are trying to avoid on a gasser....detonation...or compression ignition. *I am not saying that you should just bolt a turbo onto a diesel and every thing will be dandy. *It should still be part of the overall engine design. *But it is not as big of a challenge or strain as it is on a gas engine.

*

 

[FF]

They ran well, looked wonderful, were heavy, sounded great - and slobbered oil like all good 6-71s.

In my experience the DD did not slobber oil when new , only after a local "mechanic" was used to service the engine.

Our "lobster boat" the 50 ft USN Utility has a "new" DD , it was stored in the can sometime in the 1950's and finally sold as surplus in the 90's .

With under 1200 hours it has only had tune one tune up (to depower with smaller injectors) and leaks not a drop.

Interesting is the unit has a "color filter" a by pass filter , but no full flow oil filter .

That's how it was done then, amazing to any DD owner is the oil stays car like clean , not dark black till about 50 hours , where it starts to get darker till the 125 change out.

"last 6-71s 485 (?) hp" when used in fish killers at speed get about 1000 hrs to rebuild.

 

[cd30ketch]

If an engine was designed to have a turbo then I would not worry about the turbo being to much for the engine. But as far as high hours on a turbo, the concern is with the impeller hitting the housing due to wear in the bushing. If you shell a turbo the the head needs removed to inspect for debris. Also, though not a big problem with boats, the air filter must be kept clean. A restricted intake can cause oil to be sucked past the seals in the turbo.

 

[FF]

"If an engine was designed to have a turbo then I would not worry about the turbo being to much for the engine".

This is true but not the problem.

Too much engine for the boat ,,, a 200HP or more turboed engine gets really IFFY when asked to run 40 hp hours on end.

Where a turboed 65 hp would be really economical at creating that 40 hp at cruise.

Blame the advertising guys , most only step aboard dockside at a boat show , if then.

 

[RickB]

FF wrote:Too much engine for the boat ,,, a 200HP or more turboed engine gets really IFFY when asked to run 40 hp hours on end.

Yet another idiotic statement from someone whose marine engine knowledge is stuck in the 1930s.

Take a look at the marine performance curve for the Cummins 6BT5.9M, a typical 6 cylinder turbocharged marine diesel engine as might be found on a large number of passagemaker type boats.

It produces 211 hp at 2600 rpm at its intermittent rating, and 180@2500*in its medium duty rating. The engine*delivers about 40 hp at around 1350-1400 rpm which is about the middle of its rated operating range of 800 to 2600 rpm when driving a "well matched" propeller. The manufacturer developed the power*ranges, warrantees the performance within that range, and allows continuous operation below 2300 rpm.

The short version is the manufacturer is quite happy with backing up*its promise with cash that the engine*will produce*40 hp for up to 3000 hours a year.*Do you think maybe they know something FF doesn't?*

 

[FF]

RATED POWER OUTPUT CURVE
rpm kW bhp
2600 157 210
2400 152 204
2200 155 207
2000 149 200
1800 137 183
1600 121 161
1400 100 134
1200 80 107
1000 57 77
800 42 56
FULL LOAD TORQUE CURVE
rpm Nm lb.-ft.
2600 574 423
2400 606 447
2200 671 495
2000 712 525
1800 724 534
1600 719 530
1400 679 501
1200 636 469
1000 547 403
800 500 369
FUEL CONSUMPTION - PROP CURVE
rpm l/hr gal/hr 2600 44.9 11.9
2400 35.7 9.4
2200 28.2 7.4
2000 22.2 5.9
1800 17.4 4.6
1600 13.2 3.5
1400 10.4 2.7
1200 8.0 2.1
1000 6.3 1.7
800 5.1


Above is a transfer of the information Rick does not understand.

Notice at 1400RPM the engine "prop graph" shows 2.7GPH , perhaps 50 HP , but probably only 40 as the engine is so inefficient at that speed..

AT 1400 Rpm of "rated power output" (what the mfg warentees) the engine produces 134 HP .

134 divided by 40 or 50 is only about 1/3 or so of the rating.

"Live long and prosper ?" Probably at 100 hours a year but not for 1000's.

The numbers are there , but you have to have a concept of what you are reading , and an idea of what diesels LOVE!

In a word , WORK!!!

 

[RickB]

FF wrote:The numbers are there , but you have to have a concept of what you are reading ...

That is the first thing FF has ever written about an engine performance chart that is even near the truth. Too bad he is incapable of taking his own advice.

Look at the prop curves FF,*the power actually absorbed by the propeller, not*the*power that the engine is capable of delivering to the shaft when connected to a dynomometer.

If that is the best you can do after stewing over this for 3 days you should find another hobby or another place to publish your nonsense. *When is it going to dawn on you that you really should just stay out of engine conversations. Your contributions are the equivalent of what I might provide to a forum on cooking Chinese food. Give up FF, your stuff is getting further and further from reality every day.

 

[FF]

Look at the prop curves FF, the power actually absorbed by the propeller, not the power that the engine is capable of delivering to the shaft when connected to a dynomometer.

That is exactaly the point you are failing to understand.

The minor power absorbed by the prop (40 maybe) is only 1/3 of what the engine is rated for at that RPM, 134 HP sez the guy that built it.

Only by proper loading can a diesel give efficiency , 1/3 of its rated output in minor .

THe "proper" loading is at the selected operating RPM , not just at flank to check a prop top RPM for 10 min a year.

A CPP is one solution to getting the loads up a bit .

When we ran the numbers for a Box Boat the solution was the ZF 2 speed tranny , slow down , shift the tranny to spin the wheel FASTER and it would then absorb more HP.

Combined with a CPP in a really skinny boat the results should be grand.

YES the operator would have to understand the system operation , an idiot need not apply.

 

[Carey]

RickB wrote:

*
FF wrote:The numbers are there , but you have to have a concept of what you are reading ...

That is the first thing FF has ever written about an engine performance chart that is even near the truth. Too bad he is incapable of taking his own advice.

Look at the prop curves FF,*the power actually absorbed by the propeller, not*the*power that the engine is capable of delivering to the shaft when connected to a dynomometer.

If that is the best you can do after stewing over this for 3 days you should find another hobby or another place to publish your nonsense. *When is it going to dawn on you that you really should just stay out of engine conversations. Your contributions are the equivalent of what I might provide to a forum on cooking Chinese food. Give up FF, your stuff is getting further and further from reality every day.
*

Why so hateful Rick. Don't you have some smail animals to torture???

*

 

[RickB]

Carey wrote:Why so hateful Rick. Don't you have some smail animals to torture???

Because idiots who post nonsense should be pointed out as idiots. If you see that as hateful it is a shame and is really your own problem, not mine.

If you torture small animals in order to release your frustrations then you probably should seek professional help rather than suggest others*adopt your method ... that sort of thing hasn't been acceptable since FF learned everything he would ever know about marine diesels.

As you might be able to tell, I have little patience for fools.

*

 

[Nomad Willy]

I think the rest of us as individuals should determine if FF is an idiot. He expresses himself in strange and difficult ways frequently but I think he knows a great deal and I listen to him often.
Rick, your constant attacks in this social club I find unacceptable.
The 2 speed transmission would work well IF one knew how to use it properly and would need the appropriate ratios.

 

[RickB]

nomadwilly wrote:I think the rest of us as individuals should determine if FF is an idiot.
He expresses himself in strange and difficult ways frequently but I think he knows a great deal and I listen to him often.

Rick, your constant attacks in this social club I find unacceptable.

The 2 speed transmission would work well IF one knew how to use it properly and would need the appropriate ratios.

I find his misconceptions and lack of knowledge without the wisdom to refrain from*misinforming those who come for information to be irresponsible. I find that truly unacceptable so I guess it's a draw.
**