Marine engine question ??
Trent D. Sanders
My newly aquired Islander 29' has an Atomic 4. It's water cooled, using
seawater through the engine / exhaust. Using seawater, or some variation of
seawater/freshwater cooling which depends on through hulls, seawater and with
all the corrosion problems, etc, seems [to me] to be really dumb.
Why can't you use an engine with a radiator and fan, with it's own self
contained coolant, etc, just like in a car? Other than the problem of
supplying cooling air [ducting?], why not? Or am I thinking too far "out of
the box"?
An example of what I'm talking about is this 3 cylinder Kubota diesel. It's a
self contained package, with radiator and all. If you'll "copy" the http
thingy [below] into your browser you'll see a picture and all the details on
it.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1731994123
For that matter, you could even go so far as to use an old VW "upright" 40hp
engine from a "Bug" [if you wanted a gas engine, I don't]. Don't even need a
radiator there, and it weighs half of what the Atomic 4 weighs.
So, just wondering,,, is there a reason, or is it that it's just "convention"?
Trent Sanders
"Cimba"
Marina Del Rey
So. Calif.
Steve
is why air cooled engine are a MISERABLE FAILURE in boat.
The boat going through the water has a "station wagon" effect and the hot
air from the engine, be it air cooled or radiator cooled doesn't leave the
boat very well. You end up with a pocket of hot air in the very stern of the
boat or in the cabin.
I had a marinized 2 cylinder air cooled Wisconsin engine in a boat when I
sailed in Rhode Island. Even in the winter time, the cabin got so hot you
couldn't stand it and it stayed hot for hour after the engine was stopped.
The only way to escape the heat was to go up on the bow and level the
helmsman to suffer.
Another factor to consider is that the exhaust has to have cooling water
anyway. I dry exhaust system will generate more heat than the engine it's
self.
--
My experience and opinion, FWIW.
Steve
S/V Good Intentions
Jim Landers
you think about how most car radiators work, they need air flow through them
to cool effectively. Underway it's provided by the motion of the car. At
rest it's the fan. The car occupants are well separated from the engine
compartment. I guess you could rely on a big fan, but I'll bet your cabin
would get pretty hot.
"Trent D. Sanders" <gonzo...@aol.com> wrote in message
news:20020521203129...@mb-da.aol.com...
Jere Lull
Not a dumb question. Some manufacturers have installed air-cooled
engines. Other companies have learned from their mistakes.
Other posts dealt with the problems of the radiator well. Another aspect
is that water-cooled engines are (generally) more reliable than
air-cooled, and tolerances can be quite a bit closer. Running whatever
water you're floating in directly through the engine is the cheapest
solution and works pretty well for -- a while. The more recent "fresh
water" cooled engines are exactly what you describe except that instead
of air flowing through a radiator, you have "raw" water through a heat
exchanger (another name for a radiator).
The most efficient home heat pumps/air conditioners use ground water
instead of air to remove (or add) heat to the system. Ounce for ounce,
nothing beats water for absorbing heat.
--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 sailing from Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ annotated pics) http://members.dca.net/jerelull/BVI.html
rh...@darkstar.ca
wrote:
>I'm going to ask a really [maybe] stupid question here. About marine engines.
>
>My newly aquired Islander 29' has an Atomic 4. It's water cooled, using
>seawater through the engine / exhaust. Using seawater, or some variation of
>seawater/freshwater cooling which depends on through hulls, seawater and with
>all the corrosion problems, etc, seems [to me] to be really dumb.
Freshwater cooling is an option for the Atomic 4. Join the Atomic 4
Sailnet board at www.sailnet.com for more details if curious.
R.
Al Levesque
One variation on the radiator is having the water circulate
through piping outside the hull. Those I have seen ran the pipe
fore and aft up close to and not extending below the keel or
skeg. Never heard how effective they were nor how safe from
damage.
Matt Colie
The only stupid question is the one that you are not willing to ask.
Here goes.....
There are two parts required to the answer the question that you seem to
pose.
The first is to cooling method.
With the boat swimming a wonderful heat sink, why would you use air? If
corrosion is an issue, I will get to that a bit later. Air cooling is
problematic at best (many new motorcycles are now liquid cooled - that
should be a hint). If you compare the heat exchanger (radiator) and
cooling fan(s) of an industrial package to a passenger car, you will
find dramatically larger parts than you might expect. When you loose
the ram air through that heat exchanger and the air flow through the
engine box, things change a whole lot.
Did you know your car cools some of the oil with the dwell time in the
pan? (Boats don't do well in that category.)
This is just part of why a passcar motor called a 300HP motor in the
car's brochure will be rated at 200HP as an IM (industrial-Marine) with
the same basic parts (I won't get into the tricks the manufactures would
play to pump published ratings.)
I have know four air cooled boats (not counting lawnmower outboards) in
my experience. All built for very good and specialized reason. Three
were liquid cooled one was air. The air cool was an airboat the a VW
engine and a propellor (you don't even want to imagine how load that
was). Two were passcar motors (a boat with a three speed floor shift?)
that were later required to do massive upgrades to the raditor/fan
arrangement and other things to just get by. The best rig was the heat
exchanger and fan on the pilot house roof, and a fan and core in the
pilot house for comfort (this was Maine). The one that had started out
as an stationary package still had trouble getting the amount of air
around it that it needed just to get by.
The next issue is corrosion.
There is a part of the entire picture that you have missed probably
through no fault of yours anyone you know. The history involved is not
very far way. Prior to plastic boats (when Universal designed their
engines), twenty was a elder statesman, and they very seldom made thirty
years.
I was told by a manufacture's rep many years ago that the Universal
engines were built for one thousand hours at rated load (respectable,
for the day) and a twenty year corrosion life with seawater. At that
time, most sailboats rode at an open mooring (many people never got near
fifty hours a year). Diesels of the day were dramatically larger,
heavier and much more expensive than the Universal engines. Not to
mention the fact that they were leaky, smelly and generally nasty things
(the nice little engines we know now simply did not exist). Diesel
boats could always be identified by the black transom.
If someone was to have a modern boat with a little diesel and not have a
closed cooling system these days, he would be very foolish. Apart from
the difference it will make to the capability to manage corrosion, the
temperature control that is so important to a diesel is afforded much
better control.
I hope this does answer what question you may have.
Matt Colie A.Sloop "Bonne Ide'e" S2-7.9 #1
Lifelong Waterman, Licensed Mariner and Perpetual Sailor
Trent D. Sanders wrote: <carefully snipped>
> I'm going to ask a really [maybe] stupid question here. About marine engines.
>
> My newly aquired Islander 29' has an Atomic 4. It's water cooled, using
> seawater through the engine / exhaust. Using seawater seems to be really dumb.
>
> Why can't you use an engine with a radiator and fan?
Rich Hampel
exposed along the keel to accomplish cooling of the engine.
Corrosion of the cast iron componentry of most marine engines is not
really such a problem; as it takes typically 20-30 years of raw water
cooling service to rot out an engine. The MAIN problem with raw water
cooling is that the engine internal temperature must be held to less
than 150 degrees F. to prevent the precipitation of carbonate salts....
otherwise there really isnt a problem short term.
Jeff Morris
radiators. I'm not sure if it applies to all boats or just vessels with
passengers for hire, such as 6-pak boats. I think it doesn't matter where
the radiator is located, because I remember thinking that this would mean
that the old Everglades airboats would be illegal.
-jeff
"Trent D. Sanders" <gonzo...@aol.com> wrote in message
news:20020521203129...@mb-da.aol.com...
Peter Wiley
> I'm going to ask a really [maybe] stupid question here. About marine engines.
>
> My newly aquired Islander 29' has an Atomic 4. It's water cooled, using
> seawater through the engine / exhaust. Using seawater, or some variation of
> seawater/freshwater cooling which depends on through hulls, seawater and with
> all the corrosion problems, etc, seems [to me] to be really dumb.
>
> Why can't you use an engine with a radiator and fan, with it's own self
> contained coolant, etc, just like in a car? Other than the problem of
> supplying cooling air [ducting?], why not? Or am I thinking too far "out of
> the box"?
>
> An example of what I'm talking about is this 3 cylinder Kubota diesel. It's a
> self contained package, with radiator and all. If you'll "copy" the http
> thingy [below] into your browser you'll see a picture and all the details on
> it.
>
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1731994123
That auction has closed, so I can't comment on the particular engine.
Leaving that aside, I have looked closely at a Yanmar industrial,
water-cooled diesel that's probably similar. All the comments other
people have made WRT car engines etc are irrelevent. These motors are
designed to run at constant speed under load. The Yanmar quotes peak
and continuous power, for example. They run generators, air
compressors, water pumps and similar heavy duty items, generally at
1800-2200 rpm which is the rev range their continuous output is quoted
at. They have adequate cooling capacity for their power output.
They're industrial engines, not consumer level products.
Caveats I'd have:
1. Cooling air exchange in a constricted space. Either ducting or a
water cooled heat exchanger using seawater for the other loop and
eliminate the radiator. This needs an extra pump for the seawater
side. Not a difficult engineering proposition.
2. Exhaust gas venting. If you have a seawater heat exchanger, use the
seawater as per the current method to cool/muffle the exhaust.
Alternatively look at a dry stack and muffler. Depends on how much
room you have, how loud the motor is, how long you run it and what
your tolerance for noise is. Feasible, though.
3. Marine gearbox. How are you going to couple the motor to a box?
Where do you get the box from? How do you deal with thrust loads?
These problems are solveable too, but you need to have an idea how
you're going to do it.
Actually, if people know where you can buy a robust 2:1 or 3:1 F-N-R
gearbox with thrust bearings rated at up to 20HP continuous, I'd like
to know.
> So, just wondering,,, is there a reason, or is it that it's just "convention"?
I think it's mainly convention. I'll look at going this way myself,
but keep in mind that I have a metalworking machine shop at home, and
am in charge of a marine logistics group for a big research
organisation. What's simple & feasible for me, might cost someone else
a lot of money.
Peter Wiley
HLAviation
>seawater through the engine / exhaust. Using seawater, or some variation of
>seawater/freshwater cooling which depends on through hulls, seawater and with
>all the corrosion problems, etc, seems [to me] to be really dumb.
>
>Why can't you use an engine with a radiator and fan, with it's own self
>contained coolant, etc, just like in a car?
Air flow for proper cooling is the base reason, although if you look around,
you'll see air cooled Listers and Deutzs in a few boats. These are usually
cold climate boats though. For water cooled with a radiator, the trick is to
put a reversed fan on it to push the air away, and the radiator has t be
tightly shrouded to a vent stack to the deck. This system works very well for
generators on boats that may need to keep the gen sets running with the boat
out of the water, like lift boats and boats that work up north with wide tidal
ranges and go arground at certain times of day. On a 29' sail boat, I don't
see a good way of setting this up.
http://hometown.aol.com/hlaviation/