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Old 19-01-2016, 18:58   #181
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Re: Ideal Generator?

I wouldn't put old fashioned electric cook top in my boat but the induction cook tops are much more efficient than the old ones. One of the advantages of induction (well even the old style electric cook tops) is the lower amount of H2O that gets put in the boat from cooking. A significant issue in higher latitudes. I think Rich (Cruise RO ? I forget his user name...) is cooking with induction cook top powered by inverter, solar and LiFePo batteries. The electric cooking didn't work very well with lead acid batteries but he seems to be happy with the current set up. I don't know if he needs a genset to bake in the oven. Maybe he will join the discussion. Steve Dashew uses induction cook tops with micro wave/convection oven on his FPB series boats and the owners don't mention it as a problem. He uses AGM batteries but huge banks. I think 1600 amps at 24 volts.

So I'll add my 2 cents worth.... We all like to help someone else spend money.

I love the Big Bus alternater idea. I have one on my trawler and it really puts out. I've checked it several times when it has been working on a truly depleted 800 amp bank for 30 min. and never have found it above 185 F.

In the interest of keeping things simple and using mature technology:

Option 1. Big alternator on main engine. Northern Lights genset with power take off to drive prop shaft and big alternator via cogged belts. Your concern with a genset seems to be worry about electronic problems with the generator head. This would solve that issue. Simple and less expensive. This is what I would do. Clean and well tested equipment. You could easily put two big alternators on either aux system.

Option 2. Put 1 big alternator on your main engine. Use a Northern Lights genset with a hydraulic pump on the power take off if are going to want other things driven by hyd. Which may make sense. Put another big alternator powered by a hyd. motor. With the modern soft seals there is no reason a properly installed system should leak. Hyds work thousands of hours a year on excavation and farm equipment with great reliability. If you go with hyd be sure to have an experienced pro design the system for you. If the generator has an electronics issue you can power the alternator with the gensets engine. You can drive the main prop shaft with the genset and a hyd motor. This would make sense if you wanted to power winches and thruster with hyd also. I would also add a electric hyd. pump so I could use winches without having an engine running.

If building a sail boat I would consider the sails satisfactory back up for a well protected propellor.
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Old 20-01-2016, 01:12   #182
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Re: Ideal Generator?

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Originally Posted by mcarling View Post
Your eating habits may be very different from mine (I'm vegan) but I'm sure I've never done 60 minutes of cooking per week, let alone per day, on land or at sea. I'm hard pressed to think of anything I've ever cooked at sea that required more than five minutes. Perhaps I'm a lazy cook.

If you spend an hour a day cooking (I'm still trying to wrap my head around that), then electric cooking would consume a large fraction of what a KW of solar would produce. I guess I would then recommend bumping that up to 1200 to 1500 watts of peak solar capacity.


Were we talking about induction cooktops?
We can easily get up to 1 hour per day. Say heating water for tea/coffee (3 mins), soft-boiled eggs for breakfst (5-6 mins), bacon or similar (5 mins). Lunch - heating something (5 mins) 2 x tea or coffee during day (2 x3 mins). Dinner - boiil potatoes/rice/noodles etc (10 mins) fry something (5 mins) cook other veggies (5 mins)

So far the total is 45 mins - and we haven't discussed hot snacks or making sauces or lots of other cooking.

And then there is baking (which will use electric unless you have a gas oven) Heating or baking rolls inthe mroning - 10 mins. baking bread 60 mins. cooking a roast, leg of lamb etc - say 60 mins. baking a quiche - 45 mins

Many of us enjoy being amateur cooks and enjoy spending time in the kitchen.
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Old 20-01-2016, 01:34   #183
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Re: Ideal Generator?




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Originally Posted by Dockhead View Post
OK, I see what you mean.

My idea (as A64 pointed out) was to use a jackshaft for the generator, not to drive the alternators off the front pulley.

If the generator is not used for backup propulsion, the alts can be driven off the flywheel end.

I think a jackshaft would be very simple and elegant, designed by a proper engineer with a flex coupling and robust bearings.

The main engine might also have a pair of school bus alts, in this case "rube goldberged" on opposite sides of the front pulley, but this is not primary power generation.

If budget were no object,
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Old 20-01-2016, 04:24   #184
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Re: Ideal Generator?

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Originally Posted by Agility View Post
Ok, so on a common cruising boat and normal electric galley I'd agree.

With a catamaran and LifePo batteries a KW of solar and induction cooktop I think you'd be OK. Underway you'd need a water generator to keep up with the autopilot/radar/etc. In you use too much energy or no sun, use two Balmar 165 Amp AT-Series alternators (Dual 1/2" vee, serpentine) to top off batteries.

I'll be living with this configuration soon and will let you know if it does't meet our needs.

I do carry propane and two gas burners along with a gas oven in case this doesn't meet our needs or in case we loose electricity. I would have used a convection microwave but wife didn't like that and it required more inverter and more battery so I kept it (sort of) simpler.
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Originally Posted by mcarling View Post
Unless one is cooking for a small army, the time an induction cooktop is running is not going to result in a huge addition to one's electricity consumption. With a kilowatt of solar and sufficient LiFePO4 batteries, I think you should be in good shape. I would love to never carry propane again.
I'm with A64 on this, cooking with electric takes way more power than a KW of solar will support. I'm about ready to upgrade my solar and I'm thinking 700-800 watts just to keep up with household loads (zero heating). I would guess minimal cooking would require 1.5KW or more of solar.

Propane is fit for purpose, lots of BTUs and much more efficient usage.

Propane = 91,500 BTU/gallon
Electricity = 3,413 BTU per KWH

Quote:
One BTU is the amount of heat energy required to raise one pound of water by 1ļF. Water weighs 8.33 pounds per gallon so we can calculate that one gallon of water requires 8.33 BTU to raise the temperature 1ļF.
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Old 20-01-2016, 04:36   #185
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Re: Ideal Generator?

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Originally Posted by DotDun View Post
I'm with A64 on this, cooking with electric takes way more power than a KW of solar will support. I'm about ready to upgrade my solar and I'm thinking 700-800 watts just to keep up with household loads (zero heating). I would guess minimal cooking would require 1.5KW or more of solar.

Propane is fit for purpose, lots of BTUs and much more efficient usage.

Propane = 91,500 BTU/gallon
Electricity = 3,413 BTU per KWH
I can't say anything about electric cooking from solar. Maybe that's a bridge too far.

But electric cooking on a boat which uses a lot of AC power, and has good redundant generating capacity, is no problem. I have an induction hot plate and electric microwave/grill even now, on my present boat with relatively small (420 A/H x 24v) lead-acid battery bank, and have had to cook for four or five people exclusively on this when we ran out of gas last summer.

It works fine. The single school bus alternator easily runs all the electric cooking, whenever the main engine is running, and otherwise you just plan your generator runs to coincide with the heaviest cooking times. To whip up something simple, make coffee, etc., the batteries cope fine.

This would not work as well on a boat which doesn't use much AC power, because the key to efficiency is synergy between different tasks. Running the generator when you have several heavy tasks at the same time.

LiFePo batteries will make this even much more efficient, due to the huge absorption rates and short, efficient generator runs.


As a matter of systems architecture, it makes a lot of sense to use ONE type of power for as many different things as you can, THEN make your source of that power as robust and redundant as you can.


Propane is efficient in terms of energy density, and is more pleasant to cook on, but is terrible in every other way, particularly safety, and the pollution and water vapor it spews into the confined space of a boat interior. I can't wait to get rid of it and will never look back.
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Old 20-01-2016, 05:26   #186
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Re: Ideal Generator?

High Latitude, which I have no experience with is I think a completely different animal than the tropics, equipment wise.
I can see how a completely different boat design is warrantied, with completely different systems.
From the cooking thing, I think if you actually timed it (I haven't) I think an hour is possibly optimistic, it seems to take forever to boil a pot of water, and seemingly cooking doesn't begin for some things until the water boils. For us Southern boats, electric cooking doesn't make sense as propane is widely available and cheap, and we usually always have the boat opened up for the breeze. It is a safety issue, no way around that, just have to respect it I guess.
Just the most ineffective use for electricity possible is to create heat by electric resistance, now it will be argued that it is actually very efficient, but the energy requirement is massive
I am sort of a little bit of an electric boat in that I have enough inverter and battery capacity that I can run the fwd AC all night off the bank, but that does mean a generator run in the morning, and the deeper you cycle, the shorter the life of the bank.
Next bank might be Life-Po, I think that is what will make more of an electric boat make sense, even more so than Solar, as Life-Po is OK with PSOC and has a high acceptance rate, with my AGM bank, acceptance rate is high for only maybe half the charge time, last 25% time wise I'm only able to trickle the charge in, but to keep from killing the bank, it has to be done.
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Old 20-01-2016, 05:37   #187
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Re: Ideal Generator?

DotDun,
Help me out, rough calculations have it taking 27 AH to raise one gallon of water from 70F to 212F to make it begin to boil, is that correct?

I got there by 212 - 70 = 142 degrees x 8.33 = 1183 BTU
1183 BTU is .346 KWH or 346 WHR ? if you have a 13V bank, that's 26.6 AH?
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Old 20-01-2016, 08:10   #188
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Re: Ideal Generator?

You really need to recognize the difference between regular electric cook tops and induction electric cook tops ! My introduction to induction appliances was a gift from my daughter of an induction water pot. I'm a tea drinker so this makes sense for me. This thing will heat 8 cups of water to boiling quicker than a gas stove or a 1200 watt micro wave. Just amazed me! The response to change of heat is as fast as gas. Safety is also an issue. The cook top itself does not get hot. The pot does but when you take the pot off the stove within seconds you can put your hand on the stove without getting burned.

Steve Dashew delivers the FPB 64 with induction cook top and micro wave / convection oven and expects the boats to be able to anchor for several days without using a genset. Last I checked they were installing 1600 amps at 24 volts of AGM batteries. I have a high level of confidence that if the Dashews use this system it will work reliably.

The electric ovens are still the old style unless you are willing to live with a combo micro wave / convection. I've dreamed of a galley with an induction cook top, a microwave/convection oven and a diesel oven/heater. With LiFePo this may work with solar and very occasional genset or big dc generator use.
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Old 20-01-2016, 08:40   #189
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Re: Ideal Generator?

Quote:
Originally Posted by a64pilot View Post
High Latitude, which I have no experience with is I think a completely different animal than the tropics, equipment wise.
I can see how a completely different boat design is warrantied, with completely different systems.
From the cooking thing, I think if you actually timed it (I haven't) I think an hour is possibly optimistic, it seems to take forever to boil a pot of water, and seemingly cooking doesn't begin for some things until the water boils. For us Southern boats, electric cooking doesn't make sense as propane is widely available and cheap, and we usually always have the boat opened up for the breeze. It is a safety issue, no way around that, just have to respect it I guess.
Just the most ineffective use for electricity possible is to create heat by electric resistance, now it will be argued that it is actually very efficient, but the energy requirement is massive
I am sort of a little bit of an electric boat in that I have enough inverter and battery capacity that I can run the fwd AC all night off the bank, but that does mean a generator run in the morning, and the deeper you cycle, the shorter the life of the bank.
Next bank might be Life-Po, I think that is what will make more of an electric boat make sense, even more so than Solar, as Life-Po is OK with PSOC and has a high acceptance rate, with my AGM bank, acceptance rate is high for only maybe half the charge time, last 25% time wise I'm only able to trickle the charge in, but to keep from killing the bank, it has to be done.
Running A/C for hours uses a lot more energy than doing a little cooking.

We have a medium-sized battery bank of 420 Amp/hours x 24 volts.

On passage we typically have 4 or 5 people on board, often Brits and/or Russians, two nations who drink tea continuously. We boil water with a 1.5kW electric kettle, which will boil up enough water for 4 or 5 mugs of tea in two or three minutes.

This gets done virtually every hour, 24/7, and it makes no noticeable dent in the battery bank. Then on top of that, the microwave is used pretty continuously for meals and snacks under way. We charge typically once in 24 hours on passage under sail. Last year with my batts nearing the end of their lives, maybe twice in 24 hours. That's with all electronics running 24/7, pilot running, lighting, electric winches, and the inverter always on.

The next boat will have two or three times the usable battery capacity, so I'm really quite sure that electric cooking will be a non-issue.


My father was such a power nazi on his boat (before he got solar), that he wouldn't even let you use pressure water, when we were off shore power (!). Supposedly for the sake of saving power, but I think he was also saving water, which he was also fanatical about. You had to use the galley foot pump and carry water wherever you needed it. I swore from an early age that when I got my own boat, it would have so much power and so much water, that no one would ever have to be subject to such policies
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Old 20-01-2016, 09:59   #190
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Re: Ideal Generator?

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......

Propane is efficient in terms of energy density, and is more pleasant to cook on, but is terrible in every other way, particularly safety, and the pollution and water vapor it spews into the confined space of a boat interior. I can't wait to get rid of it and will never look back.
It would be interesting to examine how many boat fires are caused by electrical (or gasoline) vs. propane.

Since I don't frequent the higher lats, our boat is normally 'open' during cooking.
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Old 20-01-2016, 10:26   #191
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Re: Ideal Generator?

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It would be interesting to examine how many boat fires are caused by electrical (or gasoline) vs. propane.

Since I don't frequent the higher lats, our boat is normally 'open' during cooking.
Here in the UK, we have propane boat explosions several times every year. Note that accidents with propane are not fires, but explosions. I guess this must be one of the leading causes of serious injuries on boats.

https://www.pressandjournal.co.uk/fp...ion/?piano_t=1

River Thames boat explosion leaves six injured near Maidenhead | Daily Mail Online

Four hurt in devastating boat gas explosion - Birmingham Mail

That's three just in the last year, just in the UK, and just in ten seconds of Googling.

Gas explosions on boats are a very, very serious risk. Like all risks of this type, can be mitigated somewhat by good practice, good maintenance, etc.

But there was a terrible gas explosion some years ago in Poole Harbour on board a Royal Navy training yacht using the absolute best possible practices. The cadets even pumped out the dry bilges with a manual bilge pump as an extra precaution to get any lingering gas out (anyone on here do that?). A cadet lost a leg (IIRC).

So it is impossible to make a gas system on a boat 100% safe.

If there's no choice, then no reason to worry about it -- just make it as safe as possible. But if you do have a choice -- why take the risk? I hate having gas on board.
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Old 20-01-2016, 10:36   #192
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Re: Ideal Generator?

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Originally Posted by a64pilot View Post
DotDun,
Help me out, rough calculations have it taking 27 AH to raise one gallon of water from 70F to 212F to make it begin to boil, is that correct?

I got there by 212 - 70 = 142 degrees x 8.33 = 1183 BTU
1183 BTU is .346 KWH or 346 WHR ? if you have a 13V bank, that's 26.6 AH?
That looks right for a theoretical calculation. Then you have to add the inefficiencies associated with:

- 70% of the BTUs of diesel are wasted running your genset.
- XX% of the electricity is wasted converting AC to DC to charge the battery
- XX% of the battery power is wasted converting DC back to AC
- etc.
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Old 20-01-2016, 13:48   #193
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Re: Ideal Generator?

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Originally Posted by DotDun View Post
That looks right for a theoretical calculation. Then you have to add the inefficiencies associated with:

- 70% of the BTUs of diesel are wasted running your genset.
- XX% of the electricity is wasted converting AC to DC to charge the battery
- XX% of the battery power is wasted converting DC back to AC
- etc.
If I were to boil a gallon water I'd certainly start the engine. With induction cook top no problem. And then cook the king crabs. And if I have king crabs a bit of diesel heat below warms me up.
I made moonshine once with propane.. It took forever to warm up and two tanks of it to get it done
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Old 20-01-2016, 13:52   #194
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Re: Ideal Generator?

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If I were to boil a gallon water I'd certainly start the engine. With induction cook top no problem. And then cook the king crabs. And if I have king crabs a bit of diesel heat below warms me up.
I made moonshine once with propane.. It took forever to warm up and two tanks of it to get it done
I think we need your 'shine recipe

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Old 20-01-2016, 14:06   #195
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Re: Ideal Generator?

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Running A/C for hours uses a lot more energy than doing a little cooking.
Yes it does, and therefore I don't, but I have enough battery capacity to do it, I have on occasion run the fwd AC when it's hot and we are motoring as I have enough Alternator to allow it.
My 5K AC draws 5 amps at 120 VAC, so 50 at 12VDC, ignoring losses as I'm not smart enough to calculate those anyway and 50 is a nice round number for the math challenged, but with a 660 amp bank, I have 300 usable with 30 as a safety margin, assume I use 100 AH for everything else, that leaves 200 for the AC or four hours of run time, then get up in the morning and crank the generator. To do that would I believe greatly shorten the life of my bank and if it's that hot, just run the generator if you have to have the AC and cool the whole boat as your going to run the thing anyway. I guess maybe that was my point, be tough to have a full electric boat and not burn Diesel. I won't say not possible, but I bet you would be eating a lot of cold sandwiches
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