RE:T&T: Generator recommendations
Chris Grubb's question about needing more "umphf" for his anticipated
air conditioning addition reminded me that I will likely be adding
another A/C unit to the CALYPSO soon to help cool the main cabin down on
hot days. We have only a single 16,000 BTU (120 VAC) which we duct to
the area of concern (i.e. main cabin for day time hot weather activity,
and aft cabin for sleeping). It was added when we moved to Florida from
San Diego where none was needed. It is not really adequate for the main
cabin when air AND the water we're sitting in are both hot. Generator
power is a 7.5 KW Onan MDJE. My plan is add another 120VAC-powered A/C,
possibly as big as 16,000 BTU. Original unit is a packaged unit under
the settee while new one will be split with compressor in the ER.
Estimates at this point are that the genny will handle them both running
ok, but the potential for both units starting simultaneously is not
viewed with joy. A timing circuit between the two to prevent such an
occurrence is planned. For shore power, we have two 30-Amp inlets with
the current A/C unit being the exclusive user of one of them. The cord
gets a little warm (not hot) when first cooling off the boat from a
beginning temp of around 90-plus F sitting in 86-degree water
(compressor running continuously for 6 hours). I am thinking of running
the second AC off the other shore power 30-Amp input with care given to
shedding it off the bus when powering other high energy use devices like
the electric stove/microwave/etc. Typically at the pier the second
shore power circuit has very little beyond two battery chargers, and
under counter reefer, and maybe a 1.25 KW water heater going. When
cruising, the water heater will seldom be powered by electricity, and
the reefer can be run off a dedicated 800W inverter, if it and the new
air conditioner have trouble sharing the circuit. The initial (not
actually aboard the boat) power estimate by the marine air conditioner
guy I plan to have come give me a more complete look is that the power
available is adequate.
I may have to downsize the new A/C unit to fit the power available, but
with a timing link between units and attention paid to what's consuming
power, I am hoping to be able to move ahead as presently theorized. I
really do not want to introduce 240VAC and 50-Amp cabling etc to this
32-year old GB woodie. I just want to run a bit cooler when mother
nature forces me inside to escape her punishment for daring to be living
in Florida in the summer.
I am hopeful that those of you with similar sized boats with multiple
air conditioning units installed as well as the usual suspects on the
T&T who so generously share their expertise and experiences will point
out some options/pitfalls to me on- or off-line, as you deem
appropriate.
Thanks.
Rich Gano
CALYPSO (GB42-295)
Southport, FL
Rich Gano wrote:
I may have to downsize the new A/C unit to fit the power available,
I really do not want to introduce 240VAC and 50-Amp cabling etc to this
32-year old GB woodie.
REPLY
When looking at available air conditioning systems, keep in mind that not
all of them are created equal.
One of the biggest names "Marine Air" doesn't bother with soft start and
they do not have the most efficient compressors that modern technology can
ofer.
A smaller company called Mermaid in Fort Meyers FL did a lot of research
to find the most efficient compressor with soft stat.
The difference in power comsumption, not to mention size of genset needed to
start the air conditioning is considerable.
Mermaid now sequences the start of the cooling water circulation pump and
the main compressor to reduce even further the start surge. Large diameter
hose and pipe for the cooling water also helps reduce the amountof current
drawn.
This is something worth considering when trying to air condition a boat with
limited amounts of AC power available.
Quite often the large volume "name brand" products are relying on their
market presence to sell their product instead of actual technical merit.
They don't really care about refinements. They are driven strictly by sales
volume and the non discriminating buyer who accepts "national name brands"
simpoly because they are there, ends up paying the price down the road in
terms of operating costs and also in terms of greater cost to delive the
energy for such power hungry appliances.
Regards
Arild
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Thank you Arild. I know I can always take your comments literally to
the bank, and I will place Mermaid at the top of the list.
-----Original Message-----
From: A Jensen [mailto:elnav@uniserve.com]
Sent: Wednesday, August 04, 2004 12:02 PM
To: Rich Gano; Trawlers-and-Trawlering
Subject: RE: T&T: Generator recommendations
Rich Gano wrote:
I may have to downsize the new A/C unit to fit the power available,
I really do not want to introduce 240VAC and 50-Amp cabling etc to this
32-year old GB woodie.
REPLY
When looking at available air conditioning systems, keep in mind that
not all of them are created equal. One of the biggest names "Marine Air"
doesn't bother with soft start and they do not have the most efficient
compressors that modern technology can ofer.
A smaller company called Mermaid in Fort Meyers FL did a lot of
research to find the most efficient compressor with soft stat.
The difference in power comsumption, not to mention size of genset
needed to start the air conditioning is considerable. Mermaid now
sequences the start of the cooling water circulation pump and the main
compressor to reduce even further the start surge. Large diameter hose
and pipe for the cooling water also helps reduce the amountof current
drawn. This is something worth considering when trying to air condition
a boat with limited amounts of AC power available.
Quite often the large volume "name brand" products are relying on their
market presence to sell their product instead of actual technical
merit. They don't really care about refinements. They are driven
strictly by sales volume and the non discriminating buyer who accepts
"national name brands" simpoly because they are there, ends up paying
the price down the road in terms of operating costs and also in terms of
greater cost to delive the energy for such power hungry appliances.
Regards
Arild
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This thread on air conditioning and power cords resurfaces each summer on
the trawler list.
Surely the large scale black-out in the North East last summer taught us a
lesson.
We cannot continue to consume electrical power in such a wasteful manner.
Even if we can afford the cost, it amounts to profligate and conspicuous
consumption of the worst kind.
Now before someone jumps on me about living in the PNW where heaters are
more of an issue than air conditioning, let me point out that I lived back
east for 40 years before moving out here.
When I built my home I designed it for central air conditioning. I even went
so far as to install the duct work etc.
My friend was a dealer and I could have bought the equipment at cost. And I
occasionally worked for him doing installs.
However I also found that in the process of improving my overall insulation
and building envelope seals I eliminated the need for air conditioning for
all but three weeks of the summer season.
Even if cost is not an issue, how about availability?
Most marinas have a finite limit on how much power the service transformer
can handle.
When every boat in every slip consumes maximum power the voltage droops in
all the dock feeder circuits.
Sometimes it droops so far that you cannot run any motor equipment. And you
also increae the potenmtial for an electrical fire due to circuit
overloading. Someone mentioned their shore cord getting warm. How many
people don't even check that?
So maybe you are careful and so on, but how about the other guy next to you.
If his boat burns, your might get scorched in the process.
And then there is the small problem of the utilities not being able to
generate enough power to supply demand.
Given the choice of cutting off a hospital, a factory or a marina, which
customer do you think the utility operators will decide to cut off first in
the event of a brownout?
Can you imagine the air pollution of every boat ran their gensets while
still in the slips because the power was out?
This is why I think energy efficient equipment should be a major
consideration when deciding on replacement or upgrades.
There are effective alternatives to brute force air conditioning and
unrestricted power consumption.
Sunlight reflection, shading, e films on windows and hatch covers not to
mention insulation al help reduce the heat absorption of th ecabin
interiors. Simple fan ventilation also helps.
Evaporative cooling techniques hav ecome a long way since the days of the
Romans and the Moors with their cooling tower equipped castles in the midle
ages.
While perusimng a trade magazine I noticed a Florida company advertising
outdoor air conditionignfor the cockpit of sports fishing boats.
That' right! Outdoor air conditioning for the boat cockpit. They use a
finely atomized spray of plain water.
As the fine spray evaporates the air is chilled about 15 degrees below
ambient.
Simply hosing down the deck and cabin top wil also help cool down the
interior.
Again the evaporation of the water is what does the trick.
And these techniques use less energy that the old R-12 Freon based air
conditiners.
Cheers
Arild
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This thread on air conditioning and power cords resurfaces each summer on
the trawler list.
We cannot continue to consume electrical power in such a wasteful
manner.
Even if we can afford the cost, it amounts to profligate and conspicuous
consumption of the worst kind.
Arild,
Where you live ok.
Dwn. here I anchor in shallow water. If it is 25ft deep I find myself
looking for a shallower spot. Soooo no power windless, I raise the anchor
with a manual winch. I don't think you can get away with that on the left
side.
Right now it is 6pm and 95 degrees with a heat index of 102. This is dwn
from the last few days of 110 heat index.
Our summer includes MAY, June, July, Aug., and Sept.and Oct. aint exactly
cold! It is not strange , at all , to have the a/c on on Christmas day.
The Wife and I conserve gen set time by not boating in the summer. We stay
in our air-conditioned home. As I tell friends , yes the boat has a/c but
if I want to stay inside with the a/c on I can stay home a lot cheaper.
We just blt. our home and used top notch insulation all around , widows
etc. This only and I mean only lessens the amt of elec used to cool there
is no getting away from it, period. Those of us in the south would not
expect you to do with less heat !
.
CCC
M/V CC RIDER
CHARLES C. and PAT CULOTTA, Jr.
Patterson, La.
http://www.geocities.com/charlesculotta/
A Jensen wrote:
A smaller company called Mermaid in Fort Meyers FL did a lot of research
to find the most efficient compressor with soft stat.
Arild, they look great...but, as far as I can tell, they do not have split
systems. Impossible for me to use...where do you find the room? And who
wants that noise in the living spaces?
Bob
Robert Calhoun Smith Jr
M/V MARY KATHRYN
Hatteras 58 LRC
Chesapeake Bay
Having lived in Louisiana, I know he has not used as an excuse, though he well could have, even expounded on, the intense humidity also present there.
And he makes a good point about at home or on the boat.
It seems to me that waste is where our moment of focus is at the time.
It may be the size car, the number of cars, the styrofoam cups we use or the doggy doo left on someone else's property.
Generally I have found life is such that we should take each moment in its time and waste not with that moment, or with what we do.
It gets awlful hot out here in the Central Valley of California also, but not as bad as Louisiana, that's for sure.
I'd have my air conditioner on too.
Brian
Charles Culotta cculotta@cox-internet.com wrote:
This thread on air conditioning and power cords resurfaces each summer on
the trawler list.
We cannot continue to consume electrical power in such a wasteful
manner.
Even if we can afford the cost, it amounts to profligate and conspicuous
consumption of the worst kind.
Arild,
Where you live ok.
Dwn. here I anchor in shallow water. If it is 25ft deep I find myself
looking for a shallower spot. Soooo no power windless, I raise the anchor
with a manual winch. I don't think you can get away with that on the left
side.
Right now it is 6pm and 95 degrees with a heat index of 102. This is dwn
from the last few days of 110 heat index.
Our summer includes MAY, June, July, Aug., and Sept.and Oct. aint exactly
cold! It is not strange , at all , to have the a/c on on Christmas day.
The Wife and I conserve gen set time by not boating in the summer. We stay
in our air-conditioned home. As I tell friends , yes the boat has a/c but
if I want to stay inside with the a/c on I can stay home a lot cheaper.
We just blt. our home and used top notch insulation all around , widows
etc. This only and I mean only lessens the amt of elec used to cool there
is no getting away from it, period. Those of us in the south would not
expect you to do with less heat !
.
CCC
M/V CC RIDER
CHARLES C. and PAT CULOTTA, Jr.
Patterson, La.
http://www.geocities.com/charlesculotta/
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Arild,
Where you live ok.
snip<<<<
The Wife and I conserve gen set time by not boating in the summer. We stay
in our air-conditioned home. As I tell friends , yes the boat has a/c but
if I want to stay inside with the a/c on I can stay home a lot cheaper.
We just blt. our home and used top notch insulation all around , widows
etc. This only and I mean only lessens the amt of elec used to cool there
is no getting away from it, period.
REPLY
If live-aboad boats were built to the same insulation standards as houses,
it would use a lot less energy.
I did not say you should do without A/C
What I said was there are ways to achieve comfort levels and using less
energy.
With proper attention to radiant heat rejection, insulation and window
films, the load on the air conditioner would be lessened. Instead of a
20,000 BTU unit you might only need a 16,000 BTU or instead of a 16,000 you
might only require a 12,500 BTU unit.
If you can reduce your shore power current draw from 30 amps to 25 amps
while maintaining creatuer comforts, that is a significant reduction. And
that is really the point I was trying to make.
Admittedly the Gulf area is perhaps the worst place for combined heat and
humidity.
However, not every list member boats there and some of the most vociferous
critiques I received were not from that area.
If I was building a boat for use in th eGulf ara i can assure you that
insulation, radiant heat shields and such would be as high on the priority
list as anything electrical.
And if I was considering a stock production boat, only those that would be
easy to upgrade would make the short list.
Ther are several ways to make the electric power system aboad much more
efficient.
Trouble is most people are not interested in even looking into ways and
means of doing that.
regards
Arild
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Arild says,
There are several ways to make the electric power system aboad much more
efficient. Trouble is most people are not interested in even looking into
ways and
means of doing that.
I paraphrase that to
There are ways to make the power system much more efficient. Trouble is some
people are not interested in even looking into ways and means of doing that.
Its called NUCLEAR. And so that its boating related, "As in submarine and
aircraft carrier".
Bill
Bill Cooke wrote:
I paraphrase that to There are ways to make the power system much more
efficient. Trouble is some
people are not interested in even looking into ways and means of doing that.
Its called NUCLEAR. And so that its boating related, "As in submarine and
aircraft carrier".
Bill
REPLY
You don't even have to go that far.
The new 87 foot USCG cutters are all powered by 3 phase AC. Not the more
conventional split single phase 120/240V
Power is generated by conventional Northern Light gensets buit the output is
3 phase.
All motor loads run better on 3 phase. Smoother starting, lower surge
current, better power factor and so on.
So why don't the big boat builders use this approach?
I asked this very question of the electricians at a major builder her in the
PNW
Answer: They said they had enough trouble understanding single phase 120V,
never mind going to 240 3 phase. DUH!
Secondly, trying to convince the old established design engineers to try
something different than what they had been doing for the past twenty years
would be a hard sell.
In othe rwords people are afraid of change. Any change i\enve if it is an
improvement.
The technical facts are: 3 phase motors are smaller and lighter for the same
horsepower.
There is no unbalanced neutral current to deal with.
At 240 V the current draw for the same load is half of what you need at 120V
so you don't need the big 50 amp shore cord.
And that translates into less weight of copper needed for your wiring
system.
If you look at the plugs at a marina chances are it is tio white wier pin
that is burnt or becoming brown.
Why? Because of unbalanced neutral currents. In other words this is a
significant source of electrical fires in the AC system.
Even if you only have a single phase fed, it is technically possible to
convert this into a 3 phase system on board.
But once again most people are to scared to even look into this option.
So I stand by my original claim.
There are ways to rerduce your power consumption, lessen the surge demands
on your genset and thus reduce th esize of generator you ned to buy to power
your air conditiners. In addition there are several options available to
lessen the heat load on any air conditioner system used on board a boat.
No one said yo uha dto do without air conditioning. I merely pointed out
that I sucessfully used the mitigation techniques to reduce the heat load
so much that in my case the designed for air conditioning system proved to
be not needed.
In hotter climates the required size would have been greatly reduced over
what conventional design thinking would call for.
And that reduces the amount of power I would have to purchase or generate in
orde to be comfortable.
regards
Arild
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