Generators Diesel/gas what's the deal?

[Hermit Scott]

I asked a question about propane before, because I was getting conflicting facts. I am getting the same conflicting facts about diesel and gas generators. Some people said 'if you have propane on a boat you have a death wish'. Others were like 'yeah, we use propane so what?' One boater even told me it was illegal. Then mainesail refered me to the standards for propane use by the american boating society of people with boats, or whatever they are called.
Gas generators are soooo much cheaper than diesel. I know some of you guys use honda 2000 generators, which are gas. Do you keep them in a compartment somewhere or do you put them up on deck when they are running or do you keep them up on deck all the time because it's bad to put anything containing gas in a closed space? And what do you do about the hot exaust gas if it's in a compartment?
And this is what I am really wondering, what do you use them for, charging batteries, running the freezers etc.? Because now that I have studied sail boat systems a little, I see that some have generators and some rely on the engine for most of their power to charge the batteries.

 

[Don S/V ILLusion]

Let me try to give you both perspectives so you can make an objective judgment.

First, even if you have an alternator large enough to efficiently and quickly recharge a large battery bank, running the engine with no load is not good for it so it is generally not an ideal way to maintain power. If it's a stock alternator, it can't effectively recharge but that's a different discussion.

Diesel gensets are generally larger and definitely expensive compared with gas powered ones. Arguably, they are more durable as well. Clearly, diesel eliminates the explosive potential of gas so their benefits/drawbacks are obvious. Their exhaust contains a lower carbon monoxide concentration which most presume means it is safer than a gas engine exhaust, however, diesels emit a proportionally larger volume of exhaust and therefore produce CO in similar volume which can easily become as concentrated so the exhaust safety argument is a wash.

Gas gensets require separate storage, both for the gas (which most of us already have for the outboard) as well as the genset itself. This is often the limiting factor as many boats don't have a properly ventilated space in which you can safely store the genset when not in use. When in use, it is probably wisest to run it on deck away from people and as it makes noise, can be considered objectionable to your neighbors.


Regarding purpose, the obvious of charging the batteries, making hot water for showers, running the air conditioner, the Admiral's hair dryer and a myriad of other things too large a demand for an inverter.

Re ABYC standards, they recommend against use of gas gensets but they are written to the lowest common denominator in the sense they are cautious of us idiot boaters. Often times, common sense, which is the best form of seamanship, plays a big part in handling gasoline regardless of where, boat or otherwise.
What did I forget?

 

[Hermit Scott]

What do you use to recharge your batteries, and what caused your 2002 boat fire?

 

[Stu Jackson]

Good questions, and like any boat

related issue, there's always at least sixty nine ways to do things.

People use generators to make hot water through the electric side of their water heaters and to charge batteries. The Honda eu2000 is ubiquitous and very popular as is the 1000 but it won't heat water.

Alternator charging is a very long topic, but some of our conclusions after years and years of use can be found in this thread: http://c34.org/bbs/index.php?topic=4454.0

Since each boat is different, storage is an individual issue. Many of our C34 folks know where they can put them, and there's only a few spots. Up on deck when running, most drain the fuel out before storing. Think "portable" for these generators. They have some odd electrical issues related to reverse polarity, which, if you'd like, I can connect you some long discussions, here and the C34 and C36 'sites.

Because diesel engines are HEAVY those are built-in ones.

You're quite correct in your conclusions.

I'm also sure that if you haven't yet you'll do an energy budget to size what kind of system you're planning.

 

[Don S/V ILLusion]

What do you use to recharge your batteries, and what caused your 2002 boat fire?

Hermit - I have a Xantrex 40+ charger hooked up to my 440 amp/hr bank for charging.
Regarding the fire, two separate investigations failed to find the cause.

Stu - I haven't had a problem running my water heater off the Honda 2000 as long as i or my wife don't simultaneously try running the microwave or A/C.

I should add that if I had the option, I would much prefer a diesel genset.

 

[Benny]

Bpoth Don and Stu have presented a fair view of both generators and their use. Probably better than I could have done. My philosophy is get something that works for you; I know I can recharge my batteries by running the inboard diesel engine but if I can get the same results by running a cheaper generator I choose that path. At my latitude I need to run A/C at anchor and my diesel powered alternator will not provide for that so that sealed the deal. A diesel generator uses the same fiuel as the boat and keeps from using that wicked and exlosive gasoline but they are costly and mostly permanently installed. As mentioned since I already use gasoline for the dingui outboard it does not add any safety or convenience over a gas generator. My main concer in the diesel/ gas question other than price is portability. I like the fact that that I can take it home to deal with hurricane power outages or for regular maintenance and repairs. I don't frequent pristine anchorages where you would feel bad to break the tranquility so the Honda 2000eu is fairly quiet and definitely makes less noise than the music system from the sportsfishermen with the neon underwater lights. Yes, you have to run it on deck but the old Honda seems to be impervious to the elements. I'm surprised I missed being mentioned the short running time of the gas generator when run at over 1/2 load. I fabricated and installed an out board gas tank which provides me in excess of 24 hours running time. If you point the muffler end towards the stern of the boat you will usually have the fumes blow out the back of the boat. In one instance I was anchored in a river and the current was stronger than the wind and I guess it blew the exaust to wards the cabin triggering my CO detector. It had already turned dailight and I had overslept but got up with no fuzziness nor headache and had certain doubts wether the alarm was triggered by CO from the generator or my exhaled gases. I carry gas in 5 gallon jugs attached to the stanchions and allow about 1 1/2 gallon per consecutive night I plan to stay away from shore. I run A/C, charge my batteries, run refrigeration and in the morning perculate my coffee. Those are my only needs and the Honda gets it done in about 12 hours running time.

 

[Hermit Scott]

Energy Budget

This is what I currently have. I have 250 amphour bank(2x125) and a 35 amp alternator(hitachi).
I have a Don Casey sailboat electrics book for all the basics of things.

It gets miserably hot down here, reminds of the middle east too much. I want to be able to run the alternating current air conditioner while on the hook, at least during the hottest parts of the day. (I know that's a tall order) It is a 1,600 Btu unit. A small refrigerator, water pump and hot water heater, lights and whatever else is necessary.

At a minimum... I need at least another 250 amphours. A 3 or 4 stage charger and a 100 amp alternator.
This is where I am going to complicate things. I do not want to put a 100 amp alternator on my engine becasue it's a 12 horse power. Also they say running the diesel with a small load, as mentioned here is bad for engines. But I see alot of people charge their batteries that way anyway. So, to charge my batteries I want to get a generator of some sort and run that through the 3 or 4 stage charger.

One option I am considering for running the air conditioning is getting a DC generator and use an inverter for the alternating current for the airconditioner. I read that in a Nigel Calder book, but that seems tough on batteries. If my calculations are correct the AC unit takes about 40 amps @12V (470 watts) to run, not including the spike to kick the compressor on which can be 4 times that but I don't know for sure because I haven't measured it. But he says the batteries will be able to take the spike which is only for a second or so and I could run a smaller DC generator. Too bad I don't have a DC airconditioner.

I have a compartment that has the back wall as the transom. Behind the helm that you can sit on while your are at the helm. (wouldn't it be easier if I knew the word) what is that compartment called again?I would like to have a generator that will fit into there that I could vent out of the transom and somehow run the exaust out of the transom or back of the boat somewhere. Does any one have a permanent generator back there? Dealing with the hot exaust seems to be the worst part of it.
What do you guys think of that set up?

 

[newly anonymous]

there are better options

Because now that I have studied sail boat systems a little, I see that some have generators and some rely on the engine for most of their power to charge the batteries.

You might want to study a bit harder, because some of us use wind turbines and solar panels, and still manage to keep our batteries charged while on the hook.

 

[Hermit Scott]

I said SOME have generators and SOME rely on their engine... Guess what SOME others do...nit pick people's posts. I'm suprsied we don't have mandatory spelling bees on here.
And I bet you don't run an airconditioner on a solar panel and a wind turbine

 

[Don S/V ILLusion]

Hermit
Presuming you have a 16,000 BTU A/C (think it was a typo when you said 1600), it is hard to imagine running that off batteries, regardless of how you charge them. Roughly, that is a minimum of 150 amps at 12VDC. No solar panel or other reasonable 12V source can accommodate that demand and as you know, the start-up current is higher. Your 250 amp bank will last MINUTES if it would work at all.

If it is a 1600 BTU unit, my apologies on the typo comment but I don't think that size would suffice to cool one room on a boat, never mind the entire boat.

There are only two ways you can get A/C on the hook, a diesel genset or a gas genset.

I think the word you were looking for is a lazarette (sp?) or locker aft which is where I store my gas Honda although it is vented at the bottom but your's may not be. If not, it's an easy fix.

 

[Hermit Scott]

Don, Thank you for catching that. Yes that was a typo, 16,000. I have the manual, it also said it needs a 30 amp 115V breaker. I'm not sure why that is, other 16,000 Btu ac run on 15 amp.
The 6,000 Btu sure made the calculations alot more feasable. lol
I think the idea that Don Casey was talking about is only running an air conditioner while you have like a 2000 watt DC generator charging the batteries. So essentially running the air conditioner with the generator but using the batteries to buffer the spikes.

Lazarette..that's what I have heard it called.
So I guess if I had a honda 2000, or any 2000 watt generator, I could run my air conditioner with it and run that to a xantrex charger to charge the batteries?
Do you have a thick extention cord that you run to the charger and then unplug it and hook it to the air conditioner circuit, or do you just run a cable directly to the A/C panel in your boat and then be careful not to exceed the wattage limit of the generator? and then the Xantrex will draw from the A/C panel in the boat to charge the batteries?

 

[Hermit Scott]

Benny are you running the AC the whole time and the generator 12 hours?

 

[Don S/V ILLusion]

Don't get the issue of using a DC genset through batteries to avoid spikes but presuming the author knows what he is talking about. My question is - if you are going to run a generator, why not just run it direct to the load? Spikes generated by a genset won't harm an A/C compressor motor.

What you plan is precisely what I do - that being, use the Honda to run the A/C and the charger, sometimes simultaneously. What you might find, however, is that if the batteries are drawing a full charge, the Honda may not have sufficient power to run both together but that too is at most a slight inconvenience.

If you get serious about buying a Honda, send me a private message as I found a great source (read - cheap, free shipping and insurance included) you might want to contact for a quote.

There are two ways you can consider when wiring everything together - the easy way and the permanent way:
Permanent - install an auto cutoff switch which selects between shore power and genset output source as the boat's 110VAC supply; or
Easy - Run a heavy duty gauge wire extension from the genset to a pigtail adapter which plugs into the boat's 110VAC shore power plug.
Either option provides 110VAC throughout the boat, incl the charger.

This entire concept of A/C, elec coffee makers, hair dryers, microwaves, etc is the antithesis of sailing for many people but in my case, to keep the Admiral happy, it's imperative for me to make sailing as pleasant and as far removed from the concept of camping as practical.

 

[Maine Sail]

You're likely...

You're likely going to need a bigger generator for a 16K BTI air conditioner. The EU 2000 Honda is MAX rated meaning short spikes to 2000 watts. The nominal rating is 1600 watts. A 16K BTU air conditioner that needs a 30 amp breaker will likely draw, when running, between 1350 and 1650 watts. This does not take into account any inrush start up loads which the generator may trip on. The EU 2000 has a 20 amp circuit your airconditioner needs a 30.

I say take off the shirt, drink a cold one a dip into the water every now and then. I have lots of friends who have circumnavigated and only one ever had a genset but none had AC and all spent considerable time in sweltering locals. I'd try to save the AC for the dock or buy a diesel gen set or a bigger gas version..

BTW why 16k BTU? That is HUGE amount of cooling for a 30 foot boat!!! 5-6k is more than enough.

 

[Bill Roosa]

An alternate approch

With few exceptions ALL cruising boats have a diesel engine in them. This provides the following if you can stick it all in the engine compartment:
DC battery charging via a high output alternator.
Refer and freezer holding plate draw down via an electrically controlled clutch driven compressors.
SCUBA tank recharge via a SCUBA air compressor.
Hot water for showers and dishes from the engine coolant You could get cabin heat also but who wants to cruise in the latitudes above 50 degrees?
Air Conditioning via an electrically controlled clutch driven compressor.

You will notice that alternating current is not one of the things as an inverter can handle everything (the admiral's hair dryer was the limit for me) once you get to the diesel providing the air conditioning. And after an extensive search for the perfect boat babe I found one that does not even own a hair dryer!!!! For you already admiraled guys, you might try conducting a PSYOP campaign on her to get either less girl power tool usage or more man power tool usage.

Additionally, a generous mitten full of 12 volt fans and sun screens can be a real energy reduction strategy while on the hook. And yes the first few days WO air conditioning are unpleasant but you get used to it and then it is no big deal. You do have a big swimming pool just off the stern to get cooled down in BTW.

I've looked into solar and wind and those are promising but they can't really compete dollar wise with a high output alternator and a few gal of diesel. The total cost for a 150 amp alternator is under $1000. That amount of solar or wind would be both too large to install and cost prohibitave.

If you are serious about analyzing your energy usage and want a tool to help I have an excel spreadsheet that does just that. It is free for the asking. It allows you to compare wind, solar, and alternator options and balance battery bank size with power production/consumption. william-roosa@us.army.mil

 

[sailingdog]

Hermit-

Properly installed, maintained and used, propane equipment is as safe as anything else on a boat.

Same goes for gasoline powered gensets. You really need to have a gasoline generator vent overboard, and if you're looking at installing one in a compartment, the same standards for any gasoline powered engine would apply—bilge blowers with ignition protected motors and switches, fume detectors, etc...

The two biggest reason diesel gensets are generally preferred, is the fuel is much safer to work with than gasoline... and most larger boats already have diesel aboard as a fuel.

 

[Bill Roosa]

Yea, Right sailing dog!

The

 

[Bill Roosa]

Yea, right Sailingdog

The key operative word being "properly".

I find that giving advice that includes the words "maintenance" or "properly installed" to by loaded with risk to the average DIYer and cost prohibitave to the non-DIYer.

CNG is safer and cheaper.

 

[Maine Sail]

CNG is safer and cheaper.

If you can get it! Oh and it's certainly not cheaper, at least up here in the North East, where we have all of about two dealers who are constantly out of stock. I converted my Catalina 36 from CNG to LP because I actually wanted to be able to use my stove...

It's good some areas still have it available...

 

[Don S/V ILLusion]

You will notice that alternating current is not one of the things as an inverter can handle everything (the admiral's hair dryer was the limit for me) once you get to the diesel providing the air conditioning. And after an extensive search for the perfect boat babe I found one that does not even own a hair dryer!!!! For you already admiraled guys, you might try conducting a PSYOP campaign on her to get either less girl power tool usage or more man power tool usage.

il

Bill

There is a saying that applies to your logic -
"marriage is a 50/50 proposition"
I could never find out to whom that statement is attributed
but whoever it is obviously knew very little about marriage
even less about mathematics and
absolutely nothing at all about women, especially mine.

My full respect if you have accomplished what I never could and in my case, it's a futile gesture to try