SailNet Community banner
  • SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!

Diesel Generator - Economical?

5K views 39 replies 18 participants last post by  amwbox 
#1 ·
I would like to have more power available to run stuff like hot water, air conditioning, water maker, comfort heat etc. But it seems to me that smaller diesel generators are just ridiculously high priced, yet today I started wondering if I'm not looking at it correctly. If I had an installed diesel generator there are some savings in total costs to consider. Things like:

- I probably wouldn't need to increase my current solar capacity
- a lower cost AC water maker could be used instead of a DC
- electric heat could be used instead of a diesel heater
- others will probably occur to me in time (like less need to go to a slip just for the power)

I think I'll start a spreadsheet to see how the options for/against a genset works out really price wise as maybe the cost of the genset isn't as much as it.

Anyone want to express how they think it is going to come out?

PS - and yes could just do without etc., I would say there is no need to post that but I know what a waste of time it would be
 
See less See more
#2 ·
I have one installed and I have a love/hate relationship with it... Sure its nice to have BIG power when I need it. I just hate the noise, smell, weight and diesel usage.

It came with my boat so I had no choice.. If I had a choice, I would have probably choose a 2K portable (Like a Honda).
 
#4 ·
My 6kw genset came with the boat and was non-functional due to overheating. I was all set to pull it out in favor of solar and storage space.

Then my girlfriend yanked the heat exchanger and fixed the problems. It runs freezer, watermarked, microwave and espresso maker all at the same time. That's rain or shine without regard. I can't justify replacing something that works with an expensive and less reliable option.

It doesn't get used often but it's s comfort to have.
 
#31 ·
Then my girlfriend yanked the heat exchanger and fixed the problems.
This part got my attention. We have several very capable mechanically adapt ladies on this forum but still it sounds like an interesting story.

What's up?
 
#5 ·
You are comparing initial costs. I would be extremely surprised if installing a genset didn't cost more than expanding solar capacity, a DC (or engine heated) waterheater, and a diesel heater combined. From an operating cost perspective, burning diesel for power is probably the most expensive way you can get it, at least if you look at average diesel prices over the last few years. (Yes, it's cheaper now--but it's anyone's guess if it will stay that way.) Between the two, it's extremely unlikely you will save money by installing a genset.

The real question is one of convenience and creature comforts you can't get otherwise. For example, is air conditioning on the hook worth, etc, the operating cost (initial and operating), noise, weight, and space requirement? If so, you have your answer.
 
#6 ·
At the moment, our genset (8kw Onan) is our lifeline. It runs about 3 hours a day and handles all our refrigeration, water making, hot water, battery charging (when the solar isn't) and cooking. It costs about 1 gallon of diesel a day, so at us$3.50, I guess you could say our utilities are around a hundred a month.
On these hot, super humid summer days, down here in the Southern Antilles, it is so nice to turn on the air conditioning for breakfast and also at dinner.
My recommendation would be to find a genset with as few electronic parts on it as possible. Ours has zero, just a bunch of $10.00 relays and some coils/transformers in the control box; all electric. It has over 15,000 hours on it now and is due for an overhaul, which is OK, because I'd much rather rebuild this simple reliable genset than buy a new unit where the failure of a fifty cent resistor can require the replacement of an $800+ PC board.
Even with the solar and the new windgen we are installing shortly, and the eventual propane cooking, I'll not give away the sheer luxury of being able to have 8 kw of household current (and appliances), whenever I want it. Boat drinks anyone, lots of boat drinks?
 

Attachments

#7 ·
I installed a Fischer Panda 4.2k gen set on our last boat and never regretted it for the flexibility it provided. When it was blazing hot at night in a becalmed VI bay or cove, we ran A/C...when it was cool and breezy, we slept without.

Weight? A mere ~270 lbs, probably not much more than the two extra D4 batteries and the wind-driven generator one would need to carry if one did not have the gen set....those batteries are around 110 lbs each
 
#8 ·
For me it all come see own to a AC. Everything else can be worked around with enough solar and a little boost from the alternator every now and then, but if you want air conditioning you have to have a generator. For me AC on hot and muggy nights is too much of a creature comfort to pass on, at least for long term cruising.
 
#10 ·
so far it looks that the diesel generator route is $450 less, and it of course will run the air conditioning that is already on the boat
 
#14 ·
The AC watermaker capacity is 20 gph and the DC unit is 14 gph.

Another plus to the generator that occurs to me while on the hook - hot water!
 
#15 ·
Well currently the money says

No diesel generator option - $10,450

With diesel generator - $8,080 - $9,000 depending on which generator

Both of these are only really considering heat and a watermaker. But the with generator also results in being able to run my air conditioning when wanted and has a lot more ease for getting hot water etc.

But I also realize that I could reduce the no generator option to about $4,000 if I am willing to listen to the portable gas generator. So maybe I'm just making the numbers work to support the diesel generator route.
 
#17 ·
if I am willing to listen to the portable gas generator. So maybe I'm just making the numbers work to support the diesel generator route.
I listened to the gas generator for a couple of hours yesterday in order to run the electric heater. I don't believe this is an option except for those that just can not afford or fit a real generator.
 
#16 ·
I don't even have an inverter on my boat, but then my use is a lot different than most of you and other than this summer, we don't have the hot weather to consider Air Conditioning.

While a Honda generator would be an option maybe, you then have to deal with carrying gasoline on board to full it. I hate having gas cans around so much that I got rid of my gas powered outboard in favor of an electric outboard.
 
#18 ·
Don-
You've got your costs very wrong. The solar panels will go about 25 years without any maintenance costs. The diesel genset will need ongoing maintenance, oil and oil changes, and quite possibly a tear-down and rebuild or some other major maintenance every 5000 hours or more frequently. Also, any belts, hoses, rubber parts, thermostat, etc. will need to be replaced regularly along with possibly exhaust system components and air intake filter.

Rerun your figures including all normal maintenance items (and labor time) and then see how the costs break out.
 
#19 ·
Gotta be realistic about solar, though. Sure the PV panels themselves will only degrade somewhat over 25 years...but you're going to be replacing expensive, heavy, and corrosive battery banks multiple times during that period...in addition to associated electronics which are sure to be more failure prone in a marine environment...inverters and charge controllers and monitors, etc.

Solar is still expensive power. Might be cheaper, by a small amount long term...but the advantage is more about avoiding fuel consumption and noise/vibration/weight more than cost.
 
#20 ·
One other thing I failed to mention is the bilge pumping ability one has with a generator. We have 4, 110 volt 1.25", 2500 gallons per hour submersible pumps (under us$100.00 each, by the way).
Even though the same thing could be achieved with a gas portable, it might not be practical to operate a gas gene on deck in the kind of weather one might be in, when wishing to remove 10000 gallons of water per hour from one's vessel.
 
#28 ·
the goal is to NOT stay in areas where the need for regular full time heat is a common event!!!
 
#33 ·
The story is long but the reader's digest version is that my genset is a privately cobbled marinized Kubota. It was dead when I bought the boat and it is buried deep in a cockpit locker so access is very tight.

I was trying to reach it from above and fell into the locker. The problem is that there isn't much room. I ended up head down in a handstand with the edge of the locker between my hips and knees and no way to shift. I was completely stuck and unable to lift myself out. I'm claustrophobic and was in a real fix.

She, being a gym rat and very fit, reached into the locker took hold of my belt and lifted all 280 lbs of me out of the locker.

She doesn't have much mechanicalecperience, but she is game.

She went into the locker feet first and with a bit of guidance pulled the heat exchanger and after we had it rebuilt at a radiator shop,she went back in and installed the parts. She did an oil change and changed the filter for good measure.

I love her!
 
#35 ·
"The way I see it, a diesel gen uses about half the fuel of a gas gen at the same power output. "
Fuel use is only a small part of the math, unless you have a very tiny boat. Buy a Honda, top brand, top quality, for a thousand bucks. Or a bigger one for two. Now, what diesel genset can you buy for the same price?

Diesel fuel does have something like twice the energy density of gasoline, and of course plutonium and strontium put them both to shame. But the cost of the entire system, ah, that may change the attraction.
 
#36 ·
The thing about a Honda type gas generator is that you can not permanently mount in inside, start it with a push of a button, and insulate it really good for sound. I have a potable generation already and I just don't it having advantage other than initial cost.
 
#38 ·
For what it's worth, after 13 years of owning and operating a 4.2KW Panda Generator, and hearing some decry them, and other generators, what I have observed is that the problems with the units typically arise from one (or both) of two causes: lack of use; or, lack of maintenance.

The lack of maintenance issue normally seems to arise on boats where the generator has been shoe-horned into a spot that makes access very difficult and repairs nearly impossible. If one is going to install a generator, it needs be in a position where one can get to it easily to do routine maintenance and make repairs when necessary; and, it needs to be used. In our case we had some difficulties initially because I didn't fully understand the maintenance regime needed on our unit when we first got it. Since we weren't using it much, for example, (an error in itself), I reasoned that I didn't need to worry about changing the impeller in the raw water pump. Wrong! The life of the impeller is both use and time dependent once installed as, even without much use, the vanes are distorted more or less and under constant pressure. Likewise the lip-seal in the raw water pump. The seal depends upon a tiny spring ring that holds the lips against the impeller shaft. That spring, constantly bathed in sea water, will corrode and fail unless one routinely pulls the wear-plate and injects water-proof grease into the seal to, somewhat, keep water out of the spring. An exercise that takes only a few minutes that needs be done at least annually, or whenever the impeller is replaced, if sooner. Similarly, lack of use or operations for only short periods allows the sea water to heat up but then sit in the heat exchanger and cooling galleries where salt can precipitate out, crystallize and capture sand and sediment drawn in past the raw water filter. Running the motor longer allows the salt and debris accumulations to be dissolved out--especially so if one adds a cup of SaltAway to one's raw water filter basket from time to time--and be washed out of the motor through the exhaust spout. It is often this build-up of salt/debris precipitate in the heat exchanger that impedes the flow of raw water, giving rise to over heating or the motor running unnecessarily hot, increasing wear and deterioration of the lubricants.

In short, do the maintenance, and run the motor often and for a good while each time, and most generators will last a very long time, especially so in the case of the Panda. Fortunately, I can attest to the fact that the folks running FP today are very good at offering help on the rare occasions when one does have a problem, and most often at no cost what-so-ever.

Our 4.2KW unit does a very good job of running our 16K BTU AC unit, charging of 450 AH battery bank; itself running our lights, refrigerator and freezer, and, heating water for showers and dish washing all for little more than 2/10's of a gallon of fuel per hour here in southwest Florida during the Summer. Not a bad deal in my view.

Again, FWIW...
 
#39 ·
Is it possible to solve the A/C issue by pumping sea water through some kind of radiator? If not where are you that the water is too hot for this to work?

The average home uses a bit over 1kw on average. It's a shame to have a 3+ kw generator when on average it's only partially loaded. That gets really inefficient unless you have a variable speed inverter generator.

Diesel fuel does have something like twice the energy density of gasoline, and of course plutonium and strontium put them both to shame. But the cost of the entire system, ah, that may change the attraction.
No it doesn't. Diesel engines have higher compression ratios, and therefore lower exhaust temperatures and more heat turned in to mechanical energy. It would do the same running on gasoline if you could get it to work properly on gasoline.
 
#40 ·
No it doesn't. Diesel engines have higher compression ratios, and therefore lower exhaust temperatures and more heat turned in to mechanical energy. It would do the same running on gasoline if you could get it to work properly on gasoline.
Its not twice as energy dense, but diesel fuel is in fact more energy dense than gasoline. Its something like 10-12% more energy dense.

Generally, the larger the molecule, the less volatile the compound...which means that its more difficult to make that phase change from liquid to gas. So, you're left with diesel weighing more per volume. Thus, higher energy density is attainable.

Also, diesel is suitable for compression ignition because of that higher resistance to phase change. Its a slower burn. Gasoline is more likely to detonate, and also has a much lower flash point.

As for the cooler exhaust, this more about the efficiency of the diesel engine than about the energy content of the fuel. More of that energy content is converted to work in a diesel engine. So, less heat out the tailpipe, even though the actual ignition and power stroke temps are far higher.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top