On Wed, 16 Jul 2003 18:12:25 GMT, Brian Whatcott
wrote:

On 16 Jul 2003 08:48:08 -0700, (brad) wrote:

Brian Whatcott wrote in message . ..
1900 running hours suggestds that overhaul time is due soon, maybe
very soon....

Brian Whatcott Altus OK

1900 hours time for a overhaul? I am not a mechanic, but I thought one
of the reasons one would go with a diesel is for its reliability. If I
had a piece of equipment that operated 8 hrs a day, 1900 hours would
be about 237 days of
operation . Most of the machinery ( diesel powered ) at my work
operates 24 hrs a day. The equipment does get a service ( oil and
filter change) every 250 hrs of operation. What a huge liability if
they had to overhaul every 1900 hours.


It's pleasing to hear about long-life engines.
Used to be, recips used on light aircraft had a mandated overhaul time
- for most of them it was 2000 hours. Now its "on condition" like
jets....

Comparing auto engine lives:

You would like to make 150 thousand miles plus before tearing an auto
down (certainly we are making those numbers on a pair of econoboxes
we own.) If you averaged 40 mph long term - that would be 3750
hours.

Yes, but if the auto engine spent a very high percentage of it's life
at, say, 80% max hp, you wouldn't be getting anywhere near those hours.
Cruising along at 55 mph, the average auto engine is probably only
operating at around 10% load.

Steve

Jim,

Finally, a dissenter from the Perkins crowd. I have been quite surprised at
the loyal Perkins support here. It has about convinced me that we should
stick with her.

I have had others comment elsewhere that the Yanmar is the rough running
engine and I don't understand why a three cylinder engine running at roughly
20% faster for a given power output, could be quieter and smoother than a 4
cylinder engine at that same power level. This is especially true if the
4-banger has greater displacement and would be running at, say, 3000 RPM at
max continuous rating of 37 SHP when the 3 banger is running at 3650 RPM at
a similar power level.

Of course, we would normally run much slower, say 2500 on the Perkins and
3000 on the Yanmar, easily reaching hull speed in most conditions.

I'm not sure I understand why having pistons at opposite ends of their
throws simultaneously would increase the vibration, but then, dynamics was
never one of my favorite courses. If you have a quick explanation, I am all
ears.

Thanks for your reply, the quest is interesting to say the least.

Keep on sailing,

Ken
S/V Parfait
Raleigh, NC



"Jim Woodward" wrote in message
...
I have lived with the 4-108 for about ten years (twenty years ago) and
took the Yanmar's big brother, a 4JH, around the world in our Swan 57,
Swee****er. I'd pick the Yanmar in a second.

Among other things, a 3 cylinder has inherently less vibration than a
4. (In a three, the pistons are 120 degrees apart, while in a four,
they are 90 degrees apart, so that when one hits top dead center, its
mate is at bottom dead center.)

Jim Woodward
www.mvfintry.com


"Ken Coit" wrote in message
.com...
Presuming you were looking to buy a used boat, which engine would you
rather
see in her:

Remanufactured Perkins 4-108
New BetaMarine 1505
New Yanmar 3JH3E

These are all adequate to the job of pushing a 16000 # boat at hull
speed,
so the question is one of your personal preference.

Thanks in advance,

Ken Coit
S/V Parfait
Raleigh, NC

I'll try for an answer: the pistons are moving fastest not when the
crank is at ninety degrees to the vertical but with the crank a little
closer to cylinder - so the crank and con rod are at 90 degrees to
each other.
This has the effect of introducing a vibration at twice crank rotation
rate.

Brian Whatcott Altus OK

On Wed, 16 Jul 2003 23:51:01 GMT, "Ken Coit"
wrote:
//
I'm not sure I understand why having pistons at opposite ends of their
throws simultaneously would increase the vibration, but then, dynamics was
never one of my favorite courses. If you have a quick explanation, I am all
ears.

Thanks for your reply, the quest is interesting to say the least.

Keep on sailing,

Ken
S/V Parfait
Raleigh, NC

Dave,

Thanks for the report. What reduction gear are you using and what is your
"cruising" RPM? The 17x12 seems like a large prop, I don't think I could
fit a 17 to Parfait without some surgery. She currently swings a 15R13
three-blade which is more than adequate.

Keep on sailing,

Ken
S/V Parfait
Raleigh, NC



"Dave Erickson" wrote in message
news:RGdRa.78327$ye4.52992@sccrnsc01...
I installed a new Yanmar 3JH3E two years ago and just got back from a 5000
mile, one year trip to the Bahamas and back to Salem MA. We motored almost
all the way, down the ICW and back, early 1000 hours. Boat is an 1968
Apache
37 at 15000#. Prop is 17 X 12 three blade sailor.

The engine was great. Other than things I did to try and mess it up
(flooded
four times due to faulty exhaust, fuel in the crankase due to incorrect
fuel
line tightening) it performed flawlessly and tolerated my abuse. Quiet and
smooth enough, great mileage, nothing broke. Parts available everywhere.

Check the web page for details on the trip.

Dave Erickson
Apache 37 "Second Sojourn"
www.djerickson.com

To send email, remove the xx from my email address.






"Ken Coit" wrote in message
. com...
Presuming you were looking to buy a used boat, which engine would you
rather
see in her:

Remanufactured Perkins 4-108
New BetaMarine 1505
New Yanmar 3JH3E

These are all adequate to the job of pushing a 16000 # boat at hull
speed,
so the question is one of your personal preference.

Thanks in advance,

Ken Coit
S/V Parfait
Raleigh, NC

Three cylinder 4 strokes have a rocking couple due to the power
strokes, 4 cylinder 4 strokes have a 2nd harmonic - and the latter is
said to be more smooth than the former for that reason

Brian W

On Thu, 17 Jul 2003 00:22:30 GMT, "Ken Coit"
wrote:

If I read Brian's references correctly, having opposed cylinders is good as
they are balanced. If 3 cylinder engines were smoother than 4, why wouldn't
most small engine manufacturers use them? Seems like Saab is the only one
in recent memory.

I'm no expert, but I think the 4 bangers are smoother for a given level of
output. I do wish the referenced article had addressed that question.

Keep on sailing,

Ken


"Jim Woodward" wrote in message
m...
I have lived with the 4-108 for about ten years (twenty years ago) and
took the Yanmar's big brother, a 4JH, around the world in our Swan 57,
Swee****er. I'd pick the Yanmar in a second.

Among other things, a 3 cylinder has inherently less vibration than a
4. (In a three, the pistons are 120 degrees apart, while in a four,
they are 90 degrees apart, so that when one hits top dead center, its
mate is at bottom dead center.)

Jim Woodward
www.mvfintry.com


"Ken Coit" wrote in message
r.com...
Presuming you were looking to buy a used boat, which engine would you
rather
see in her:

Remanufactured Perkins 4-108
New BetaMarine 1505
New Yanmar 3JH3E

These are all adequate to the job of pushing a 16000 # boat at hull
speed,
so the question is one of your personal preference.

Thanks in advance,

Ken Coit
S/V Parfait
Raleigh, NC

Based on my experience with Yanmar and Mack Boring (East Coast Distributor
for Yanmar), even Volvo is ahead of Yanmar, and hell will be frozen shut
before I would consider Volvo.


--
Lew

S/A: Challenge, The Bullet Proof Boat, (Under Construction in the Southland)
Visit: http://home.earthlink.net/~lewhodgett for Pictures

(Steven Shelikoff) wrote in message ...
On Wed, 16 Jul 2003 18:12:25 GMT, Brian Whatcott
wrote:

On 16 Jul 2003 08:48:08 -0700, (brad) wrote:

Brian Whatcott wrote in message . ..
1900 running hours suggestds that overhaul time is due soon, maybe
very soon....

Brian Whatcott Altus OK

1900 hours time for a overhaul? I am not a mechanic, but I thought one
of the reasons one would go with a diesel is for its reliability. If I
had a piece of equipment that operated 8 hrs a day, 1900 hours would
be about 237 days of
operation . Most of the machinery ( diesel powered ) at my work
operates 24 hrs a day. The equipment does get a service ( oil and
filter change) every 250 hrs of operation. What a huge liability if
they had to overhaul every 1900 hours.


It's pleasing to hear about long-life engines.
Used to be, recips used on light aircraft had a mandated overhaul time
- for most of them it was 2000 hours. Now its "on condition" like
jets....

Comparing auto engine lives:

You would like to make 150 thousand miles plus before tearing an auto
down (certainly we are making those numbers on a pair of econoboxes
we own.) If you averaged 40 mph long term - that would be 3750
hours.

Yes, but if the auto engine spent a very high percentage of it's life
at, say, 80% max hp, you wouldn't be getting anywhere near those hours.
Cruising along at 55 mph, the average auto engine is probably only
operating at around 10% load.

True, but proper diesel engines are designed to operate under load.
The usual and only worthwhile rating is the continuous one, and it (at
least used to) mean what it says. Fed clean air, fuel and with routine
servicing, diesel engines will run for many, many thousands of hours.
Boat engines have a pathetic life mainly due to their operators'
ignorance. The other problem is engines that are started, run for 5
minutes and then shut down again.

Personally, provided spares were still available, I'd rather have an
older engine running at 1800 rpm than a newer one running at 3600 rpm.
You need a 2:1 reduction in the first case to get your prop shaft
speed below 1000 rpm and can swing a big 2 blade prop slowly. Finding
4:1 reduction boxes - I haven't seen any commonly offered.

My nearly 40 y/o Perkins diesel in my tractor *always* starts and I
bought it in 1988. Over the last 15 years, all I've ever done is
change the oil and filters.

Peter Wiley

On Wed, 16 Jul 2003 23:59:57 GMT, Brian Whatcott
wrote:

On Wed, 16 Jul 2003 23:13:32 GMT, (Steven
Shelikoff) wrote:
///
Used to be, recips used on light aircraft had a mandated overhaul time
- for most of them it was 2000 hours. Now its "on condition" like
jets....

Comparing auto engine lives:

You would like to make 150 thousand miles plus before tearing an auto
down (certainly we are making those numbers on a pair of econoboxes
we own.) If you averaged 40 mph long term - that would be 3750
hours.

Yes, but if the auto engine spent a very high percentage of it's life
at, say, 80% max hp, you wouldn't be getting anywhere near those hours.
Cruising along at 55 mph, the average auto engine is probably only
operating at around 10% load.


This is the argument against the efforts to convert auto engines to
light aircraft use: the aviation duty is much harder, but then - the
irrigation pump engine endurance is impressive: Im not sure just how
many of those potential horses are actually pumping water, it's true.

I'm not sure it's as much an argument against converting auto engines to
light aircraft use as much as it is one that says if you do convert an
auto engine to light aircraft use, don't expect it to go as long between
overhauls as the same engine in a car.

Steve

Jere,

I agree that there is more to consider than the number of cylinders, but
there are so many variables in an installation, that I wouldn't expect two
engines of the model and age to sound the same in the same boat, let alone a
different boat. The Beta I did see on a boat was very quiet, but I don't
know whether that is because it was naturally quiet, quiet because it was
boxed with lots of insulation, or quiet because it was driving an hydraulic
pump instead of a prop.

What I do know is that Robinhood Yachts is currently using the Yanmar 3JH3E
in the same hull as our boat. If I can presume that a manufacturer that is
going to build a $250,000 boat is going to spend at least a little time
analyzing which modern engine to use, then the Yanmar is a good bet.

However, lots of people on this list love the Perkins....

Keep on sailing,

Ken


"Jere Lull" wrote in message
...
Ken Coit wrote:

I have had others comment elsewhere that the Yanmar is the rough running
engine and I don't understand why a three cylinder engine running at
roughly
20% faster for a given power output, could be quieter and smoother than a
4
cylinder engine at that same power level. This is especially true if the
4-banger has greater displacement and would be running at, say, 3000 RPM
at
max continuous rating of 37 SHP when the 3 banger is running at 3650 RPM
at
a similar power level.


There's more to vibration and noise than the number of cylinders.

Why not see if you can get a ride on boats with each?

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

Ken Coit wrote:

Jere,

I agree that there is more to consider than the number of cylinders, but
there are so many variables in an installation, that I wouldn't expect two
engines of the model and age to sound the same in the same boat, let alone a
different boat. The Beta I did see on a boat was very quiet, but I don't
know whether that is because it was naturally quiet, quiet because it was
boxed with lots of insulation, or quiet because it was driving an hydraulic
pump instead of a prop.

All true, which implies that whatever you choose, a proper installation
will make it as smooth and quiet as you require.

What I do know is that Robinhood Yachts is currently using the Yanmar 3JH3E
in the same hull as our boat. If I can presume that a manufacturer that is
going to build a $250,000 boat is going to spend at least a little time
analyzing which modern engine to use, then the Yanmar is a good bet.

Unluckily, sometimes they choose an engine by cost or some other
criteria, so while I like Yanmars, I wouldn't make assumptions. 'Course,
you might call up the factory and ask. It could well be that the Yanmar
is the best engine for some reason.

However, lots of people on this list love the Perkins....

And some who like two stroke outboards and SeaGulls.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/