Conference unifix::sailing

    I have had three different configurations of the "old and reliable"
    engins.
    A Volvo MD-2B, 2 cyl, 25hp rated.
    A Perkins 4-108, 4 cly, 60hp (?).
    A Leman-Ford 90, 4 cyl, 90hp rated.
    Each engine has had its oil and filter changed either twice a season
    or each 100 hrs. which ever happened first.
    The Volvo went up and down the inland waterway once.
    The Volvo and the Perkins went with the boats when they were sold
    after 5 years of usage. The Ford is now in its 4th year.
    Each engine was cruised at 1800 RPM and only under extreme conditions
    were they run above 2000 RPM and never longer than necessary.
    And there was never any trouble with any of them.
    I like slow speed engins.

    I now have a Perkins 48HP.  Previous boat had a slow rev Volvo.
     The Perkins was reconditioned about seven years ago.
     
    Receives only oil change attention.  Goes great.  Does not really
    charge up the battery Have thought about replacing the generator with
    an alternator, but instead bought a solar panel.  Saved the panel cost
    in a few months by not replacing trousers damaged with battery acid at
    recharge time.
    
    Have heard the rumours about the high revving new types of diesel,
    but have not come across anyone who has experienced a problem. 
    Maybe they have not been on the market long enough. 
             

Ross, perhaps you missed the worst part of the PS article on diesels. 
Some of the new Perkins engines will have ELECTRONIC controls. 

			AAARRRGGGHHH!!!

Another giant step backward in reliability, maintainability, and 
serviceability away from access to sophisticated special tools and the 
like. 

When it comes time to finally replace my more or less trusty Westerbeke 
L25, I'll look for a four cylinder engine producing about 25 hp at 2000 
rpm or less, self-bleeding fuel system, weighing 350 pounds or so, NO
turbocharger, NO electronics, etc. Gee, sounds like my L25. Westerbeke's 
current engines, built on Japanese blocks, are rather like this, too.

    the price on the yanmar 18 hp was 4800.00 plus install from 800.
    to 2000.00.....i am still recovering
    
    jfk

re .4:

If the reliability of every part in an engine is P, and there are N
parts, then, simplistically, the reliability of the engine is P**N.
Since more cylinders means more parts, the reliability of each
individual part in, say, an eight cylinder engine must be higher than
the reliability of each part in a four cylinder for the overall
reliability of the engines to be the same. 

For those who didn't see the Practical Sailor article ..... one mechanic 
was quoted as saying (approximately) 'Yanmars used to be cheap and 
inexpensive when they were buying into the market ..... now they're just 
cheap.'

Also, the trend to lighter weight and higher speed has at least three
consequences. First, less material is used (eg, iron in the cylinder
blocks), which may mean less strength. Don't forget that the heat
produced and the combustion stresses are the same for a light engine as
a heavy engine for the same power output. Second, lighter materials are
used (eg, aluminum cylinder heads instead of iron). This may increase
corrosion problems. Finally, wear on moving parts (pistons, bearings,
valves, etc) increases at least linearly (if not faster) with increased
speed. A slow turning engine will wear more slowly than a fast turning
engine. 

    I have probably the extreme opposite of modern high-speed lightweigth
    engines. My Grey Marine engine is 125 pounds, rated at 3 hp. It
    turns 450 RPM at its top, but I normally run it at about 250-300.
    I suspect it has fewer thatn 100 total parts, including all the
    bolts. The bearing surfaces are huge- the main bearings are about
    3" long and 1.5" dia. It was built in 1909, and still runs fine.
    I have no doubt I could go out to the boat today, attach its 6v
    lantern battery and start it on the 3rd or 4th turn. Its installed
    in a 17' dory, I once towed Mystic Seaports 30' whale boat, with
    10-12 passengers home with it with no apparent loss of speed. I
    think the 3 horses are Clydesdales, not Japeneese ponies!
    
    give me old, heavy, slow turning any day!

I took these exerpts from the Mechanical Drives reference issue of
Machine Design magazine.

    "Iron is said to wear better, but proponents of the aluminum
     engine say that it lasts equally long if properly maintained. 
     Iron has a greater tolerance to dirt. Ingestion of dirt is quite
     harmful to an aluminum engine."

    "Automotive, marine, and aircraft engines are considerably more
     sophisticated than small industrial engines, and aluminum is used
     successfully in large engines in these applications."

    "Diesels have acquired their reputation for being rugged heavy engines
     primarily because they are built to withstand the high firing forces
     and high high cylinder pressures that are a consequence of the high
     compression needed to produce spontaneous ignition. However, it is
     possible to build relatively light (and correspondingly less durable)
     diesels simply by cutting design margins."


Correct me if I'm wrong, but I think Dr. Diesel (the German inventor) committed
suicide by jumping of a ship at sea. Ironic - don't you think.

-Paul

>>> Correct me if I'm wrong, but I think Dr. Diesel (the German inventor) 
>>> committed suicide by jumping of a ship at sea. Ironic - don't you think.

Herr Dr. Diesel disappreared crossing the English Channel in 1913 on his 
way to a meeting with the British Admiralty to discuss selling diesel 
engines to the Royal Navy. It has been speculated that Diesel's 
disappearence was not an accident or suicide.

    	I have had experience with several diesel engines:
    		BMW single cylinder 8 hp. - good engine but high revs
    and electrical system very poorly design. Generator's stator would
    burn once a year.
    
    		Volvo 2002  18 hp. - Nice compact design, difficult
    to start in cold weather, otherwise no observed problems except
    heat exchanger's welds gave-up after 50 hrs.
    
    		In my current boat I have Westerbeke 40 1977, which
    is really a Perkins 4-107. The engine has over 7000 hrs. and runs
    tops. I was afraid it will need rebuilding however after inspection
    compression is close to specs. and there is no oil consumption.
    I have had talk with Westerbeke distribiutor out of Norfolk and
    they have a generator with the same engine which has over 30,000
    hours and still running. They said primary maintenance they do is
    frequent oil changes. I guess this shows that solidly build all
    iron engines with good maintenace record last a long time.
    
    Igor.

    I wonder if anyone has or knows of anyone who has a Mariner diesel.
    This was the Volkswagen Rabbit diesel engine adapted for marine
    use that was heavily advertised a few years back.  45 hp at 4000
    rpm.  Extraordinary power/weight ratio for a marine diesel.  I know
    they weren't all that great in the cars.  My sister's diesel Rabbit
    cracked a block very early in its life.
    
    - gene

The PS article implied that the marinized VW diesel (Pathfinder) was a 
disaster.

RE: .11, .12,

>>>  The PS article implied that the marinized VW diesel (Pathfinder) was a 
>>>  disaster.

The idea was they they'd be cheap, and they sorta were.  But has anyone 
wondered why they advertised heavily for a year and then totally
disappeared, while the car version continued to march on? 

J.

    I love my 1984 Yanmar 3GMD 22hp.  It currently has about 1600 hours
    and the only failure to date was the raw water pump which is made
    by Jabsco.  It always starts right up, has a great altenator, etc.                        
    I talked to Mack Boring, the New England sales and service center
    for Yanmar and they claim that since 1974, they have not had a single
    engine that was "worn out".  All returns have been "operator failure"
    that is, over heated, bad fuel, no oil etc.  When I spoke to them
    in 1984 they were tracking a 3GMD in a yacht club launch which they
    considered to be tough service.  It had about 7500 hours with no
    major problems.
    BTW, I typically cruise at 2500rpm.

>>> [Yanmar] claim that since 1974, they have not had a single
>>> engine that was "worn out".  All returns have been "operator failure"
>>> that is, over heated, bad fuel, no oil etc.  

Oh really? Are NONE of those "operator failures" due to failures in 
Yanmar components? In fifteen years? I'm a mite skeptical. It seems to 
me that, for instance, allowing an engine to overheat is an "operator 
failure" in one sense, but if overheating is common, then there is an 
engine design flaw. I'd be reluctant to take Mack's claims without a bit 
more data.

>>> BTW, I typically cruise at 2500rpm.

I normally don't run my engine over 1800 rpm. On the few occasions I 
have, both lubricating oil and fuel oil consumption have increased 
drastically and operating temperature has gone up noticeably. This 
implies to me that my engine will wear out much sooner at 2500 rpm than 
at 1800 rpm. In fact, lubricating oil consumption increases enough so 
that it is necessary to add a quart in as little as ten running hours. 
At 1800 rpm the engine uses a quart every 50 to 100 hours.

re the yacht club launch: This engine may well have many hours on it,
but it doesn't run continuously under full load for hours and hours at
at time. This may be a significant factor in its longevity. 

    One topic not discussed is fuel consumption.  I would expect a slow
    turning engine to be more efficient than a fast one, due to the
    rapid buildup (square function?) of internal drag as RPM increases.
    
    Any comments from the sages?
    
    Rick,

re .16:

A slow speed engine may or may not be more fuel efficient than a higher
speed engine. Internal friction, etc, is only one factor. Gas flows
through the engine (air/fuel), operating temperatures, compression
ratio, exhaust system design, throttle setting, among many factors,
affect fuel efficiency. 

However, for a specific engine: Higher speed does mean more wear,  
more noise, and higher fuel consumption due to internal friction in the 
engine and to the greater power required to push the boat through the 
water faster.

Some engine makers publish graphs of fuel consumption (usually pounds of
fuel per hour per horsepower) versus engine speed. It is from such a
graph that I estimate that my engine must produce only 8 hp at 1800 rpm
to achieve a boat speed of 5.7 knots in calm water using 0.5 gallon of
diesel per hour. At full throttle (about 2400 rpm) boat speed is maybe
6.5 knots and fuel consumption maybe doubles. Because of this, our
engine is almost never run faster than 1800 rpm. 

This data also shows that when we finally have to replace our engine
(some years hence, I hope) a smaller, less powerful (and less expensive) 
engine than our current 25 hp diesel would be adequate and acceptable. 

    I currently run a 1970 vintage Perkins 4-108 engine.  With this
    I am able to push my 17 net ton 47 foot ketch at its roughly 8 knot
    hull speed while driving a 100 amp Lies-Neville cruising altenator
    and running my refrigeration system off of the engine.  I need to
    run the engine at 1900 RPM to run at hull speed.  The engine has
    about 6800 hours on it and, with the exception of a corroded out
    heat exchanger after 15 years and a raw water pump which bought
    it at the same time, the engine has needed no attention.  The engine
    manual says that at 1900 RPM, I am generating only about 24 horsepower!
    
    I am convinced that slower running, 'low tech' engines are the only
    was to go for durability and reliability.  I have never had the
    engine fail to start or give any trouble.
    
    Two manufacturers who were not mentioned in the note which I will
    consider when it comes time to repower are Nanni-Mercedes and Cummins.
    Both of these engines are relatively heavy cast iron slow reving
    engines which are used extensively in Gensets and other commercial
    applications.  The Cummins engine I would consider is their 4B-3.9-M
    unit which is rated at 58HP at 1800 RPM.  The engine weighs about
    750 pounds with a 2/1 reduction gear so its not for a small boat,
    but thats only about 125 pounds more than the 4-108.  The reason
    this engine is appealing is that it is said to be extremely reliable
    and sells---fully marinized and ready to drop in on 4-108 mounts
    for only $5625.  Thats about 40% less than a comparable Westerbeke.
    
    The Nanni-Mercedes is also comparable to the Perkins in size and
    weight.  It is said to be the smoothest running of all of the mid-size
    4 cylinder diesels and is also a 'low-tech' slow turning engine
    with a cast iron block and head.  It is made in Stutgart by Mercedes
    and is marinized in Italy by Nanni.  It sells for just under $7000
    with gear and also drops on the Perkins mounts.
    
    Volvos 4 cylinder diesels also are said to have a pretty good
    reputation, but they do not have a unit that is set up as a replacement
    unit for Perkins and their prices are about $1K higher.
    
    If anyone is interested, I have the names and phone numbers of the
    local distributors for both Cummins and Nanni-Mercedes.  Drop me
    a note.

    I just received the latest Practical Sailor which had an article saying
    that Universal diesel parts may still be available from theirformer
    dealers.  Did Universal go belly up?  Did Westerbeke buy them out?
    I hadn't read anything about this before but maybe I missed it.
    
    

    Westerbeke now markets the diesels engines previously marketed by 
    Universal, I'm not sure about the gasoline engines. The engines are
    made by Kubota and I'm confident that one could get parts directly from
    any Kubota distributor. I am thinking of replacing my Yanmar 12 HP and
    am considering Kubota or for that mater, any other popular brand 20-30
    HP. Note, most of the small diesels are made in Japan even if they
    sport names such as Westerbeke, Perkins and I think Onan.