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Old 24-08-2010, 13:49   #46
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I realize you dislike diesel for various reasons, but the only thing I would prefer would be a small diesel genset simply for the sake of keeping petrol off my boat. As long as you have adequate forced ventilation, though, it would be reasonably safe.
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You certainly can install a diesel generator if you want. My plan when I installed electric propulsion in 2008 was that I could always install a diesel generator later if I really needed to. That is one of the nice things about an electric propulsion system you add things and change things rather easily as technologies evolve. As I found out I really don't need the diesel generator at all. The Honda 2000 generator fits my needs for charging and propulsion and I can even make ice at the same time. I have two 48 volt solar panels and a Marine AirX 48 volt wind generator in the mix too. Since I'm on a mooring or at anchor most of the time I use the Honda to just charge through the bulk charge then let the solar and wind generator top things off. If I'm at a dock then I just plug into the dockside power. As far as having petrol on board I always had to carry it onboard anyway for the Dingy's outboard. I use common sense on it's storage. But, now I only have to carry one fuel since there is no more Diesel engine. Along with all the oil, antifreeze and parts that go along with it are off the boat. Any petrol leftover can always go in my car before it goes bad unlike the Diesel fuel which would tend to just sit in the on board fuel tank.
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Old 24-08-2010, 14:11   #47
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Have any electric monohulls transited Panama?

Maybe this should be setup as a challenge. See who could be the first to transit Panama in an electric mono hull with just one propeller and less than 35' LOA that has been converted from diesel. In theory it sounds like it is possible but can one of the puddle jumpers actually do it? It would be a great educational tool.
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Old 24-08-2010, 14:35   #48
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Hi Mike,

Not that I am planning to in the foreseeable future, but if my diesel ever gives up the ghost and needs to be replaced, some sort of diesel electric system will certainly be worth looking into, particularly since I would not normally use my motor all that much on long trips.
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Old 24-08-2010, 16:34   #49
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Several people on this thread have discussed making a diesel hybrid system which certainly solves the issues of range provided that the diesel has sufficient output but in the big picture, it may not be any better for some applications. We are talking about series hybrids, not parallel hybrids like you would find in a prius. Series hybrids do not have many of the benefits mileage wise that a parallel does but a parallel doesn't make sense for boats due to the constant output nature of the application.

The biggest advantage to going to a series hybrid is that you can operate the engine at a constant rpm where it very efficient. However, in a sailboat application, this rpm is very close to what a normal cruising rpm would be anyways so if you have a good setup to start with, there isn't that much advantage. In certain applications, the ability to have the diesel somewhere other than right next to the prop is certainly helpful. In the case of a catamaran, it can make a lot of sense.

There are a few big disadvantages to hybrids. For one, every time you convert forms of energy, you loose some of it to heat. An example of a well designed electric drive system would be:
Battery charging efficiency 95%
Motor controller efficiency 95%
Motor efficiency 90% (this really depends on the type)
Gearing efficiency (almost all electric drive systems will need gearing) 95%
Total efficiency 77%

Comparing 77% to something like 30% for diesel shows that you need to store a lot less energy. If you wanted to do a fair comparison from an environmental perspective, you would need to go all the way back to extracting the fuel but that isn't the point of this. So you need to store a lot less energy but that doesn't do you any good since energy density is poor in batteries. If you go to that hybrid drive system, even if you could magically raise your engine efficiency to 40% and generate power at 95% efficiency and have no charging losses (you wouldn't be charging), your total efficiency would still be 31% which is negligibly different.

To do this, you would be adding significant complexity and weight to your vessel while probably decreasing overall reliability. If your reason for going electric were noise, it wouldn't help you at all on long trips although the short motors would certainly be more pleasant.

I have ignored the operating costs of these systems since most people just don't burn enough fuel to make it matter. On my own boat, I haven't burned $100 worth of fuel yet this season even though I have been out a lot. Installation cost is very important in all of this but it is very system specific.


There have been a few responses of people on this thread who have gone electric and are very happy with it. However, none of them have claimed to motor at 6 knots for 40 hours which is something that some of us do on a somewhat regular basis when trying to make ground. It really comes back to how you use the boat and if you need range and decent power output, electric only isn't an option and hybrid is a complicated option that doesn't necessarily offer any improvement. For people who don't feel that having the ability to motor hard for long periods of time is a safety or otherwise necessary feature, electric is great, that is why I have 3 electric cars. In my mind, anyone considering it should carefully work out the worst case scenarios for their use and figure out what size battery bank/generator they would need and make their decision from there. The equations are really easy and they don't lie, the only thing that gets messed up are the inputs.
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Old 24-08-2010, 16:43   #50
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I've been looking at 38-45' cats for a year or so, giving preference to those with lots of hours on the diesels, with hopes of replacing them with electric hybrid drive soon.

No plans for long range cruising - just island hopping in bahamas mostly, but am enthused about minimizing stops for fuel, and the quiet motoring when gen not needed.

Slightly off topic question - Any ideas on where to look for cats that need work, or have old/blown engines? Can't find much on yachtworld.
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Old 24-08-2010, 18:23   #51
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Originally Posted by Eyeback View Post
Maybe this should be setup as a challenge. See who could be the first to transit Panama in an electric mono hull with just one propeller and less than 35' LOA that has been converted from diesel. In theory it sounds like it is possible but can one of the puddle jumpers actually do it? It would be a great educational tool.
Eyeback:

I probably could not do it with my current setup. I'd have to add another charger/supply and parallel to the battery bank to get the extra current needed. I could certainly get through the canal with my current system but, not at 8 knots. BTW 5 knots was pretty much top end with my old Diesel and that was with a lot of noise and vibration. I could think of other ways to do it but, they would not fall under your criteria.
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Old 24-08-2010, 19:46   #52
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Klem:

Yes it does depend on your needs and expectations when choosing to go with electric propulsion. In my case I have a sailboat first and foremost that's how I prefer to move it. I mostly only use electric propulsion when there is no wind or I'm docking. Though I will also motor sail sometimes when I want to point up and make it around a point of land on occassion without tacking. It meets all of my cruising needs and requires much less maintenance and $$$ than my old diesel. But, I certainly would not be motoring at 6 knots for 40 hours. I've never had to do that even when I had the diesel. Anyway 5 knots was pretty much top end for the iron pig and it was a noisy 5 knots at that. If 40 hours at 6 knots is what you need yes you will need a bigger generator than I have. But, you probably could get by with a smaller battery bank since you'll be using the generator to provide the power for the motor. Or just stay with diesel like you suggest. But, like you alluded to having a generator means you have the ability to install it in other locations on board. Making for easier maintenance. This may not be an issue on the bigger boats where there is a lot of room but, on smaller ones like my 30 footer it became a real pain to access some of areas of the diesel engine. One of the reasons why I'm glad I don't need to have one on board when I went electric. But, if I did feel the need to instal one I would make sure it had easy access for maintenance. Though on sailboats most diesels don't wear out but, either rust out or suffer some type of damage from the hot cool hot cycles that they see in a sailboats intermittant powered propulsion use. I think electric propulsion is much better suited for many sailboats and how they are used. My boat is probably worse case scenerio for an electric propulsion system. I'm on a mooring and anchor out most of the time. Yet, I able to keep things charged up up and ready to go without a problem. If someone is on a gotta gotta schedule perhaps it might not be them. But, IMO electric propulsion is not just for those who are daysailers either.
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Old 24-08-2010, 20:04   #53
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Originally Posted by muskoka View Post
Has anyone looked at a diesel-electric system? I don't think running engines from batteries is realistic, but using a genset to power multiple electric drives seems completely workable. This setup has been used by ocean liners and trains for decades.

The current setup on our boat seems absurd to me: Two auxiliary diesel engines + diesel genset. If I was re-powering I'd set up a large genset hooked to two electric motors for propulsion. And perhaps have a very small genset for running house loads when on the hook. Simple and easy to service.

The advantages I can see would be to reduce the number of engines from 3 to 1 genset (or maybe 2); you could put the genset wherever it makes sense weightwise; and you could fit the electric drives on legs which could be retracted whilst sailing.
Now thats what Im talkin about, I'm not try to get ride of a diesel, just trying to get the best use out of one. Plus...no more alignment issues, yay.
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Old 24-08-2010, 22:14   #54
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Now thats what Im talkin about, I'm not try to get ride of a diesel, just trying to get the best use out of one. Plus...no more alignment issues, yay.
Windgeist:

Well you will have to do an initial alignment after the install. But, you will be aligning a 45 pound motor as opposed to a 400 pound engine. But, for me even better was the ease of access to the stuffing box
THE BIANKA LOG BLOG: GOING ELECTRIC PART 13: Motor on!
which after living with V drive transmission on the diesel was like a gift from heaven.
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Old 24-08-2010, 22:53   #55
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Astrid:
You certainly can install a diesel generator if you want. My plan when I installed electric propulsion in 2008 was that I could always install a diesel generator later if I really needed to. That is one of the nice things about an electric propulsion system you add things and change things rather easily as technologies evolve.
That really is a massive advantage - the electric system is scalable!! Whilst you're doing local cruising you go with electric, solar & honda backup. If you wanted to do longer cruising maybe you install a small genset. And you can put things where they make sense.

The problem with conventional diesel systems is that you make a decision during manufacture to install X auxiliary engines + genset. Great if the needs of the boat owners don't change. In the case of my boat that means 3 diesel engines!!! What a waste of weight, space and effort to maintain them.

I'd have loved to install one big genset and 2 electric motors. If future needs dictated we could have installed a small second genset for house loads and as an emergency backup. At the very least that would eliminate one engine.
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Old 25-08-2010, 07:07   #56
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Muskoka:

You might want to check out the Gato Verde a catamaran charter boat that has been operating with just such a system since 2006 in the northwest. They use the same motor I do in my 30 foot monohull except being a cat are using two with one generator like you would like to do.


"Gato Verde's Sustainability & Efficiency Upgrades
Propulsion: In March of 2006 the Gato Verde became the first charter vessel on the west coast to replace her diesel auxiliary propulsion engines with a plug-in diesel-electric hybrid propulsion system. The conversion to this cutting edge system involved removing the 2 old 27HP diesel engines and replacing them with Two 9000 watt Thoosa electric motors, a single 12KW diesel generator, and a large battery bank. The resulting system is quite amazing. The goals of this conversion were to:
Provide a cruising speed of 6 knots or more with the generator running
Silent electric only performance of 4 knots for at least 1 hour
Decrease underwater noise by at least %50
decrease fuel consumption by at least %30
Regeneration of electricity under sail
All of these goals were met or exceeded! If there is any wind at all on trips out of our Bellingham Cruise Terminal base of operations the diesel generator is usually not needed at all since the boat is able to get to and from the dock silently under battery power alone."

Here's a video of one of their trips and it seems to be moving along quite nicely.
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Old 25-08-2010, 07:13   #57
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electric is fine if you can plug into 30 amps avery night. plus you can install the new lithium ion batteries but you better have the credit card handy.
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Old 25-08-2010, 07:17   #58
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I'm looking for a cat hull or midsize displacement hull with a blown engine also. The last hull I bought ended up on the freeway during Ike.
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Old 25-08-2010, 07:40   #59
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electric is fine if you can plug into 30 amps avery night. plus you can install the new lithium ion batteries but you better have the credit card handy.

Pah! I'm on a mooring and anchor out most of the time when cruising. Yet, I able to keep things charged up and ready to go without a problem. Yeah, I could have gone with lith ion batteries but, I agree they are too expensive for my EP needs and wallet at this point. But, if/when the price comes down I might consider them or perhaps some other new breakthrough battery technology that comes along. Until then AGM's are fine.
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Old 25-08-2010, 09:35   #60
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Lithium is old teck now.

Battery tech is an increasingly important field of research. And just as lithium is becoming increasingly affordable it is going to be on it's way out. New battery banks are going to look more like capacitors with the advantage of being able to hold their charge longer than what most of us are familiar with when dealing with a capacitor. This will have many advantages for electric vehicles. Right now one of the biggest drawbacks to the electric car is the time it takes to charge the battery, you could travel "X" distance then need to plug in for several hours. With these new batteries you could charge the batteries in less time than it takes to fill a 20 gallon tank. Think about that. Even if you were charging a battery off of a generator how much of that energy is going into the battery? They have a fixed charge rate and it realy is incredibly low! So alot of your generated power is lost. Now more of your potential energy will be captured in you battery bank, improving fuel economy by a whole new factor. The potential energy storage for these batteries will be twice of that of a comparable battery double it's size! The obvious poit here is you can double your range or cut your weight by half when under battery power alone.

These are all short articles that show what is coming down the pipe in the next three to five years! The good news is it's all cheaper to make than what we have now!

Technology Review: TR10: Liquid Battery

Technology Review: A Quantum Leap in Battery Design
Technology Review: Big Energy Storage in Thin Films

Technology Review: Nanocapacitors with Big-Energy Storage

Technology Review: A Blended Battery Pack for Cars

Now here is the real kicker for those of you who looked at the links! The implication for people who build Ferro cement or Fiberglass hulls is boats of this type won't need batteries. The hull could be a battery. And that would be better and of greater capacity than any fuel tank.
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