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Old 04-09-2009, 22:58   #31
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Electric is definitely a reality, its just not reasonable if you need lots of power on demand for long periods. I imagine that a modest system would be ideal for those single-handers that already hate having the little outboard they keep for canal work. I'm aware of quite a few passage-making boats, unconcerned with inland waterways, canals and shipping lanes, who have sculled their small boats. So for the small boys, why not electric? If you don't use all those batteries for propulsion, you would have ample amperage for radar, running lights etc...

Someone already mentioned it, but couldn't a boat design that incorporates the use of batteries as ballast offset some of those weight issues? Afterall, most of our yachts have huge lead weights in them already, to keep it low and amidships would be a boon to stability, if secured properly.

As far as non-electric... I've always wondered, why isn't compressed natural gas considered for running diesels? It could double as cooking fuel, and be used for lighting if desired. I know it is not as readily available in some ports, but from what I understand it can be more efficient than diesel, and is considered nearly as safe.

I think my ideal (fantasy) system would be a Compressed Gas generator (and stove/heat set up), that could be used for supplemental charging of a large bank of wet cells used to power an electric motor. This would be in addition to all the other typical charging goodies. In extreme circumstances, where an extended range was necessary (rig trouble, running to port in front of a storm), I'd burn through the available battery power first, then throw a CNG generator to full RPM and motor off of the electric power it provides (unless there was a PTO that could move the shaft directly).

Ahh, gotta love pipe dream engineering. But I think it could work! >=)
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Old 04-09-2009, 23:04   #32
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BlackLight Power Inc Science.
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Originally Posted by Rising Star View Post
If you Google "BlackLight Power scam" you will get some more interesting reading.
Real life can be quite harsh; in that: sometimes we need to find a process for sifting out the wheat without getting buried in the chaff. Mountains of chaff attract globally warmed lightning.
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Old 04-09-2009, 23:29   #33
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In the end though isn't it the same thing? You burn fuel and the prop spins. It oesn't really matter that the energy you are creating goes through a battery bank. If anything it is actually less efficient. Correct me if I am wrong here. It would help if you could tell us a bit about how your system works and what a typical sail is like for you.
Here's what Rising Star posted on the thread:
Solar-Powered Motor

post #24

Electric power is a geometrical progression of speed/distance, I can power at 3.8 knots for 3 hours on one battery bank or drive at hull speed for 45 minutes. I can also "cheat" using my Honda 2000i generator. My longest usage to date was 17 hours straight.

I am retired and cruising. If you have deadlines and schedules to keep then this auxiliary system may not suit your lifestyle.

I prefer electric over diesel because it's reliable, quiet, and much cheaper.
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Old 05-09-2009, 00:39   #34
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Here's what Rising Star posted on the thread:
Solar-Powered Motor

post #24

Electric power is a geometrical progression of speed/distance, I can power at 3.8 knots for 3 hours on one battery bank or drive at hull speed for 45 minutes. I can also "cheat" using my Honda 2000i generator. My longest usage to date was 17 hours straight.

I am retired and cruising. If you have deadlines and schedules to keep then this auxiliary system may not suit your lifestyle.

I prefer electric over diesel because it's reliable, quiet, and much cheaper.
Thanks for pointing me in the right direction. What he is saying is that the generator is used to supplement the batteries in a pinch. This is a pretty cool system and would be perfect for a boat that you daysail and that is out on a mooring. I would like to see a cost analysis over 10 years for the two systems, diesel and electric, and see which one comes out on top. Everyone keeps saying this system is in it's infancy but it seems like it would work fine in a lot of applications just not cruising to far off lands just yet.

I think is is worth mentioning that a lot of people's engines do a lot more than propel the boat, they charge batteries, run inverters, cut your hands, and run fridge compressors.
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Old 05-09-2009, 06:06   #35
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OK - so it seems impossible for boats that have to motor for 10 hours and then run their fridge for 48 hours. As said above, however, one way is to use less - go for a sailing boat, skip the fridge. Go for electric motors (once available).

?

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Old 05-09-2009, 08:08   #36
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OK - so it seems impossible for boats that have to motor for 10 hours and then run their fridge for 48 hours. As said above, however, one way is to use less - go for a sailing boat, skip the fridge. Go for electric motors (once available).

?

b.
I use a 200W, 48V solar panel for my 2 motor banks (house bank seperate - with its own 50W solar panel). When anchored or out for a few days the solar panel not only fills the motor batteries, I also use the excess power for refrigeration by means of a DC/DC converter to step down power to 12V. All my refrigeration power this year has come from the solar panel. Having the CoolBlue unit that draws very little power and a super-insulated small box has been key to a small refrigeration footprint.
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Old 05-09-2009, 08:24   #38
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In the end though isn't it the same thing? You burn fuel and the prop spins. It oesn't really matter that the energy you are creating goes through a battery bank. If anything it is actually less efficient. Correct me if I am wrong here. It would help if you could tell us a bit about how your system works and what a typical sail is like for you.
The Honda generator is a last resort/emergency power item. One I have been glad I had several times in the past year.

Typically,....well, in cruising there seems to be little that is typical; however, with that caveat - a day from Tarpon Springs to Clearwater (FL) last April we used 5 minutes of 10% power to bring up the anchor and point into the wind to raise sails. Tacked half the day into the wind to reach Clearwater, took down sails in front of the bridge, and powered the next 1 1/2 miles to the marina, picking our way through the shallow bay at 3 knots - going aground within the channel markers once. Within 4 hours the solar panel had replaced the energy used.

Your results may vary
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Old 05-09-2009, 12:21   #39
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Batteries as ballast/Rising Star question/Lifeline query

One must keep in mind that if batteries are used low in the hull, there must be adequate ventilation during the charging cycle (to vent away the hydrogen gases, and in warmer climates, to keep the batteries from overheating (see thermal runaway info at Concorde Battery)). I am looking at various designs where I can install battery banks low but easily accessible (no boat currently so this is just a design project).

Rising Star, could you elaborate and give more details on your power grid on your vessel? Could you give model numbers for the DC appliances and let me know if you are using LED lighting?

Anyone out there using Lifeline AGM batteries? Other gel or AGM that you recommend?
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Old 05-09-2009, 13:39   #40
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Someone mentioned a hybrid system using batteries and a generator. I'm wondering if it would be possible to come up with a cost-effective re-powering option for a sailing cat along the following lines:

Two electric motors driving two retractable props (or one motor + two gearboxes driving two props).
A two-hour duration supplied from batteries alone.
A diesel-powered generator that automatically cuts in after two hours (or equivalent state of battery discharge).
The generator is powerful enough to run both electric motors at full power or both motors at say, 75% power + recharge the batteries.

Two hours of battery duration would comfortably take care of berthing and leaving the marina/harbour and the batteries would be easier (quicker) to recharge using solar and wind alone than 10/20/whatever hours battery usage, plus less ££/$$ on batteries.

The generator being able to supply the necessary power to run the motors directly would mean no need to continue running the generator once the props were retracted/sails were up/boat was moored.

Is this feasible, or would the cost/size of a powerful enough generator be prohibitive?
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Old 05-09-2009, 14:51   #41
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The genset hybrid way is a temptation to many. But personally I do not like it. If I am to use a genset, then just as well I can have a diesel motor.

So I know it is supposed to work and has been applied on a couple of boats, but would prefer solutions where the diesel thing is completely absent from the system.

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Old 05-09-2009, 15:22   #42
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Quote:
I'm wondering if it would be possible to come up with a cost-effective re-powering option for a sailing cat along the following lines:
Been done. The whole thing works but diesel to make electricity to make power is not a net gain or any greener. Diesel to make power directly is more efficient. You can not make any process 100% efficient so you lose on the generator then lose again on the batteries. They used 14 group 4 AGM batteries (about $700 each). You can find details on the Green Fastcat in several place on the forum. Charging 14 batteries has to be a fun thing too.
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Old 05-09-2009, 17:45   #43
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Example of electro conversion using E-pods

Hm, I guess there is always someone out there with the same thinking as yourself. Case in point is my pondering of a electro conversion of a catamaran (just recently the Gemini 105MC). Here is a website devoted to just that project, complete with pictures and work log. I am still not clear if these E-pods are the first thing that will hit bottom when the vessel runs aground. It looks like the pods are not level but on the incline up to the rudder. Anyone know of an electro conversion with a Mehe 36?

The Hurdle's focusing on sailing, boating, sailboat racing, diving and other family activities.
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Old 05-09-2009, 23:49   #44
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Been done. The whole thing works but diesel to make electricity to make power is not a net gain or any greener. Diesel to make power directly is more efficient. You can not make any process 100% efficient so you lose on the generator then lose again on the batteries. They used 14 group 4 AGM batteries (about $700 each). You can find details on the Green Fastcat in several place on the forum. Charging 14 batteries has to be a fun thing too.
But what if you only use the Genset on a very rare occasion, are only using the motor briefly to get in and out of the slip, and are recharging it with wind and solar? Then you would indeed have a more efficient rig in the long haul, you just have to look at the long term picture.
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Old 06-09-2009, 00:06   #45
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Also, what is often overlooked is that the conventional diesel drive for a small boat always uses a gearbox, which introduces losses just like the diesel-electric conversion loss. As you do not need a gearbox for diesel-electric, you gain, compensating the conversion loss (in part?).

When you use a diesel genset to charge batteries and use the batteries to power an electric drive, you loose a lot in the battery charge/discharge process. You do not have this loss when you first run down the batteries with the electric drive and next switch over to diesel genset to both drive the electric motors and charge the batteries.

I think the whole concept makes a lot of sense and it gets better with solar and/or wind gen power sources added to the picture. I would give it a lot of thought when the need for re-powering comes up.

And remember that submarines have been doing this for a long time, it's proven technology.

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