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Old 19-10-2013, 15:01   #91
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Incorrect.
I had learned that a diesel is more efficient when it is loaded up; was that bad information? People run water makers while already using their diesel to propel their vessel...and while they charge their batteries, and....
I'm open to your correcting me, but please explain how it uses more fuel to motor under diesel power while doing these things versus just motoring without these extra loads.
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Old 19-10-2013, 15:10   #92
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Re: Longest time/distance you've had to motor?

You've already explained it yourself: you're adding MORE load. Do you think a semi trailer uses more fuel when it's empty or carrying 30 tonnes of load?

Its the same thing. Let's say you're motoring using a 20kW (roughly 26hp) diesel at 1/2 power. Then you want to add a couple of extra kW load to it to charge your batteries. That power has to come from somewhere, it doesn't magically appear just because it's electricity. It comes from burning more fuel. Either your boat will go slower, meaning you run longer, or you'll have to open the throttle more to maintain speed.
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Old 19-10-2013, 15:35   #93
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Originally Posted by bryguy67 View Post

I had learned that a diesel is more efficient when it is loaded up; was that bad information? People run water makers while already using their diesel to propel their vessel...and while they charge their batteries, and....
I'm open to your correcting me, but please explain how it uses more fuel to motor under diesel power while doing these things versus just motoring without these extra loads.
Diesel engines consume fuel based on load. Propulsion is a load, as is running a massive alternator. Keep adding load and you need to keep adding fuel to maintain the load.
Diesels do operate more efficiently under load in so far as the greater the load (within the spec chart) the better the conversion of fuel to useful energy. However the idea that you can make great gains in economy by charging a battery with a massive alternator to provide more propulsion is false. Ideally you will gain efficiency if the solar and prop re-gen will allow you to motor sail without any real drain on the batteries.
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Old 19-10-2013, 15:54   #94
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Diesels do operate more efficiently under load in so far as the greater the load (within the spec chart) the better the conversion of fuel to useful energy. However the idea that you can make great gains in economy by charging a battery with a massive alternator to provide more propulsion is false. Ideally you will gain efficiency if the solar and prop re-gen will allow you to motor sail without any real drain on the batteries.
There is always a loss of energy associated with the conversion of the energy from type to type and work performed...
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Old 19-10-2013, 18:00   #95
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Re: Longest time/distance you've had to motor?

And don't forget that there is an inherent loss in the charge/discharge cycle with batteries. That is, you only get something like 80% of the energy you dump into the battery back out (exact figure depends on battery chemistry and design).

The free lunch counter is closed...

Cheers,

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Old 19-10-2013, 19:13   #96
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Re: Longest time/distance you've had to motor?

The System BRYGUY67 is referring to has advantages as follows

1.the batteries can be replenished via 3 ways Deisel (20 kva), Hydrogenerator(only when sailing) and solar, (with lithium that makes the 20KVa fairly quick to top up with a big charger)

2. with full batteries he can motor (electric) for around 6 hours at around 5-7 knots. (with the current design) without any help from solar,diesel or hydrogenerater.

3. with a little sail power he is able to produce 5kva of power via hydrogenerator to resupply the battery bank.

When the yanmar diesels 55hp are under full load (maximum required to use the generators and cruising speed propulsion) they may use around 30% more than at cruising speed.(info from a user currently at sea but subject to design)The diesels may be used to just charge the batteries and at low rpm's (no propulsion)

So with all the possibilities his boat should need diesel power for less than 50% of the time and not at all for 6 plus hours at the start of a trip.

With 1200 watts of solar and a big solar controller not counted for yet.

Don't know about most of you but 6 hours off battery is more than i would use on motors most of the time. And to know that 2 diesels are sitting there ready for use, would give me a lot of comfort, and probably less than 50 % engine hours a year.(given a standard system of motors and a generator, even less if using the alternators to charge the batteries)
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Old 19-10-2013, 19:34   #97
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Re: Longest time/distance you've had to motor?

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Originally Posted by aclmck View Post
The System BRYGUY67 is referring to has advantages as follows

1.the batteries can be replenished via 3 ways Deisel (20 kva), Hydrogenerator(only when sailing) and solar, (with lithium that makes the 20KVa fairly quick to top up with a big charger)

2. with full batteries he can motor (electric) for around 6 hours at around 5-7 knots. (with the current design) without any help from solar,diesel or hydrogenerater.

3. with a little sail power he is able to produce 5kva of power via hydrogenerator to resupply the battery bank.

When the yanmar diesels 55hp are under full load (maximum required to use the generators and cruising speed propulsion) they may use around 30% more than at cruising speed.(info from a user currently at sea but subject to design)The diesels may be used to just charge the batteries and at low rpm's (no propulsion)

So with all the possibilities his boat should need diesel power for less than 50% of the time and not at all for 6 plus hours at the start of a trip.

With 1200 watts of solar and a big solar controller not counted for yet.

Don't know about most of you but 6 hours off battery is more than i would use on motors most of the time. And to know that 2 diesels are sitting there ready for use, would give me a lot of comfort, and probably less than 50 % engine hours a year.(given a standard system of motors and a generator, even less if using the alternators to charge the batteries)
So how long do you think it would take the 1200 Watts of solar to recharge the batteries after that 6 hours of electric motoring? Even assuming no house loads?
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Old 19-10-2013, 20:16   #98
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Re: Longest time/distance you've had to motor?

Just read on the net.
US companies trialling DIESEL fuel CELLS
On trucks (4) in US
These are to run cargo refrigeration
My guess would be 5-30hp equivalent ?

Just about perfect match for many boats
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Old 23-10-2013, 06:57   #99
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Re: Longest time/distance you've had to motor?

Well I appreciate the added info. I misunderstood the info I read about diesels being more efficient under load. Overall the hybrid will use less fuel than a non hybrid wheather in a sailboat, a cruise ship or a car. In the end it's about choices; some people like to charge their batteries from diesel, others from wind...solar...hydrogeneration, etc. Each to their own. Some embrace the newer technologies and others still like their rotary dial phones and that's okay.
As for the question of how long it would take the 1200 watts of solar to recharge the batteries, the answer is "it depends" (on battery size, charge level, hours of sun per day etc) but regardless if I was on a long windless run I wouldn't cruise into port with the batteries empty. I'd use diesel propulsion/charging for the last leg and only rely on solar to top off the batteries and sustain daily power use at anchor. ACLMCK mentioned 3 ways to recharge on my boat (+ we could plug in if at a marnina...although we don't plan to do too much of that).
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Old 23-10-2013, 14:35   #100
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Re: Longest time/distance you've had to motor?

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Originally Posted by bryguy67 View Post
Well I appreciate the added info. I misunderstood the info I read about diesels being more efficient under load. Overall the hybrid will use less fuel than a non hybrid wheather in a sailboat, a cruise ship or a car. .

In a car yes, in a boat, not so much. Cars have to accelerate, sit in traffic, go up hills, brake..... boats tend to just run at cruising speed.

So cars have to have way bigger engines than they would need to just run at cruising speed. Much of the time the car's engine is working well under it's optimum speed, and sitting in traffic it's just burning fuel going nowhere.

Boats don't. When you're motoring in a boat, you're using the engine at pretty much it's optimum setting.

That's why a 10 ton boat might have only a 50hp engine, while a 1 ton car has a 100hp engine.

Using a diesel to run a generator to produce the electricity to run an electric motor to turn a prop will be unlikely to have less losses than simply using the diesel to turn the prop.
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Old 23-10-2013, 21:27   #101
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Re: Longest time/distance you've had to motor?

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Using a diesel to run a generator to produce the electricity to run an electric motor to turn a prop will be unlikely to have less losses than simply using the diesel to turn the prop.
For sure. But some seem to have this view like using a TivO to record a show and watch it later uses more electricity than just watching it live,
so why would anyone do that? The Tivo can play DVD's and download to a USB drive also so you don't need an Antenna to watch TV most of the time.
But why would anyone want one, they use more electricity than watching live TV and are more complicated, they have a file system for gosh sake!
My TV antenna works best.
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Old 24-10-2013, 05:39   #102
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Re: Longest time/distance you've had to motor?

It's too bad that diesel is the only way to charge the batteries. Seems like someone could invent a way to hydro-generate power while sailing, or use the wind or sun. Personally, my rotary dial phone works just fine. I think this whole touch tone thing is a passing fad.
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Old 24-10-2013, 06:28   #103
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Re: Longest time/distance you've had to motor?

Bryguy,

I find your approach interesting. I like the redundancy, but I simply would not do without long term propulsion option (which at this point are my trusted Yanmars). Additional advantages I see in your system: You can dock the boat with just one engine running, while you are doing the fine tuning with the other electric motor.

As for recharging, I am not convinced of any method that uses the props. In fact, I spent a lot of money to upgrade to feathering props, which resulted in quieter and faster sailing.

My personal setup is as follows: Diesels only for propulsion, 660 Watts of Solar for normal usage (fridge etc) and a generator and a big watermaker for short term housekeeping. Usually when we anchor it is water first, washing machine second, and thereafter everything is nice and quiet.

As for your reference to rotary phones, no, I am not stuck in the Seventies, but when it comes to our safety (and this is what engine propulsion is for me on our boat) I will gladly step back and let you do the experimentation. I love new challenges where they can do no or little harm, I shy away wherever a system failure could have disastrous results.

Enjoy your boat!

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Old 24-10-2013, 07:44   #104
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It's too bad that diesel is the only way to charge the batteries. Seems like someone could invent a way to hydro-generate power while sailing, or use the wind or sun. Personally, my rotary dial phone works just fine. I think this whole touch tone thing is a passing fad.
Although diesel is not the only way to charge batteries, it is the most cost effective way to get "useable power right now.!" As to development of a hydro-generator, again power or speed loss on crossing due to drag would give rise to complaints. Whether a large hydro-generator or multiple "small ones," there is, "No free lunch."
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Old 24-10-2013, 09:22   #105
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Re: Longest time/distance you've had to motor?

I dunno what happened to my post yesterday, but I'm going down the Tenn-Tom (we call it banjo country), and it probably got lost.

If you want to charge with a hydro generator, the theoretical least drag (assumes a perfect system) is 55 lbs per hp (550 ft-lbs/sec/10 ft/sec) at 6 knots--the realistic number is over twice that as my 200 watt ferris hydro generator had a drag of 40 pounds. Thus, 5 kw would be 6.5 hp, or 360 lbs theoretical and probably 5-600 pounds actual, which would put a real crimp in your cruising speed.

As far as solar charging goes, 1200 watts of solar is good for 3-8 kwhr/day, depending on insolation. If you ran at 10 kw motor for 5 hours, that's 50 kwhr, which is going to take you a week or two to put back, even if there were no other house loads on the panel.
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