Norm of Bandersnatch wrote: > > Ken has often been on the cutting edge of marine electronics so I expect > great things from him. >
Ahh flattery, I love it! <G> Wish I could live up to it! > > I have only two thoughts on the subject. > > > 1. Every time energy is changed (as in an alternator or motor), controlled, > or transported there are losses. From the fire in the engine to the > propeller, a standard engine/transmission/shaft/prop is likely to have the > least losses. You can always put a big alternator on a PTO on the forward > end of the engine. True, for a given RPM/loading it MAY have the least losses, but since a standard set up requires the engine to run at many different speeds with differing loading, and the hybrid set up can make the engine stay much closer to it optimum performance, it is a documented fact (see links below)that such a system can be more efficient than a standard set up. As I mentioned, the key to making it practical is to minimize the losses that will occur, and with modern tech these can be reduced to the point that even under the worst conditions, IE the engine with the standard set up is run at its best operating point, even then the hybrid can be very close to that efficiency, and when you then consider the entire total run times at all points, the hybrid can often come out on top. Glacier Bay has some very good info regarding this on their site. Overview; http://www.ossapowerlite.com/overview.htm From FAQ's at; http://www.ossapowerlite.com/faq.htm "4. How can you get better fuel efficiency by generating electrical power and putting it through a motor than by powering the propeller directly from the engine? Since no electric motor or generator is 100% efficient, it seems counter-intuitive that placing them between the diesel engine and propeller could improve fuel efficiency. Nevertheless, the fact is that, when a diesel-electric system is properly designed and configured, it can and does substantially improve fuel economy. (Remember, the move to diesel-electric drive for commercial ships is largely driven by the desire to reduce fuel costs.) The potential to improve efficiency is based in the fact that by "decoupling" the engine from the propeller, it is possible to reduce the substantial energy losses of the propeller while operating the engine within a more optimum power range regardless of load conditions. It is worth noting that simply "generating electricity and putting it through a motor" does not automatically accomplish this. A diesel-electric system simply creates the potential for fuel savings. A poorly designed electric drive system could be less efficient than a conventional drive. Improving fuel economy is a primary design goal of the OSSA Powerlite system." > > As for air conditioning. I have AC on board Bandersnatch but need to run > the genset to operate it. We rarely operate it, and when we do it has been > in heat mode for just a few minutes to take the morning chill off our > quarters . I agree AC on a boat is seldom needed at anchor...OTOH, I remember Singapore, man AC would sure be nice there! > > As for running the genset at a more efficient load level than the direct > drive engine, I don't see why. Either engine has only one load/rpm state > where it is most efficient, With modern inverter gensets, the RPM of the engine is de-coupled from the electrical load, since the voltage and freq are not dependent on engine speed. The result is much more efficient operation. A similar effect occurs between the controller and electrical prop motor, that is the prop motor pretty much always runs at an efficient point due to the way the power is supplied from the controller. The combonatian yeilds in effect a very efficient countiounsly variable transimission between the engine and the prop, one that is even more efficient than a fully variable propeller, so that the RPM or torque load on the engine can be pretty much the optimume for that power level regardless of what the propeller is doing. The result is a definate and very signifigant efficiency increase that can make such a set up more efficient than a standard installation. Note that in my design for my small boat I choose to be able to connect the genset to the motor via the controller instead of having it so the house bank could run the motor that way, so that in my design in pure electric mode the house banks battery power must run through an inverter first to get to the motor. This is in order to maximize diesel fuel range, since the lest losses occur in that mode this way. After all, I can only fill the diesel tank at a marina or whatever, but I can harvest alt energy all over! so I really don't see the advantage of the > genset over the direct drive in this regard since either way they would > both have similar and but unique to each load/rpm conditions to meet. > True, you can adjust both the load and the rpm on the DC genset but you can > also do the same with a controllable pitch prop on a direct drive engine > without the electrical losses in the diesel/electric system. Not as well with just a variable pitch prop. Even on USN ships such as Destroyers, the prop is able to account for only a fraction of the load matching, after that it is done by changing the speed of the gas turbines. Of course in the future it won't be done that way as the new Navy ships are going to use a hybrid drive similar to what I propose. But any boat > can be set up with the proper propeller to allow the engine to run at its > most efficient rpm/load at cruising speed. And if the conditions change, such as chop or heavy seas, strong currents, fouled hull, different weight loading for the boat, motor sailing, etc. then so will this 'set point'. In fact it is not often that a standard set up runs at its best point just as it is not often that a auto with a manual transmission does either. > > You could not power sand the boat in a yard because you cannot run the > water cooled engine while on the hill. Of course you could rig a radiator > with a fan, or perhaps pump water from a nearby river or connect the yard's > water hose when the yard boss was not around. Yes, I have seen it done, it is very easy, just fill a large drum with water and run hoses, works fine. But since my small genset was not going to be water cooled, it isn't a problem anyway. > > When attempting to back off a mud bank you will want all the power in a air > craft carrier, trust me on this. For YOUR boat...for mine often backing the main will suffice, and if not a little help from the engine is good if you want to save time and hassle. If more power is needed than pure electric mode (maybe I am on the ICW in GA and really in a sticky spot with a strong current)I could always start the genset and get more thrust than I could use! A battery powered electric motor would be > my last choice. For simply getting away from a mooring or anchorage or slipping out the bayou, it would be perfect. There are several boats here that are pure electric and they do fine in that regard. > > A wind genny of a size to put on a boat will not make enough electricity to > propel the boat. Sure it will! I know for a fact that larger boats than mine only require about 2KW to go fast enough in calm flat water to easily maneuver and get into a slip, and that would mean that a few hours of good wind with my Air Marine wind genny would provide all the power needed for harbor maneuvers. I also have solar and that helps some also, and if you then plug in the boat at the slip, you are out very little. Of course if I was going to anchor and used up all my electric power getting there, I may need to use the oil lamps for a night...oh well. But I doubt it would come to that since my led lights use such a tiny amount of power. In fact, I imagine that the force of the wind on the > wind genny would be more than the energy in the electricity it produced so > you would have a net loss when going up wind. I never said or would propose that the wind genny should drive the prop motor directly! (!) You would be better off > putting up more canvas. > > Putting electricity in and taking it out of batteries is not efficient. > Typically losses in the 10 to 20 percent area depending on load. Amp hours > also decrease with heavy loads, thence the Puckert factor. > > It is practical to generate electricity using a spinning propeller while > under sail. Never said it wasn't, I merely contend that if you are getting X watts from that, it is slowing the boat down more than the same X watts from a good wind genny would be. And a wind genny works well at anchor, regen almost never does. IMHO regen is just not worth the extra cost and complexity for a smaller boat. For a larger boat it would be different, as the size of a comparable wind genny might get to be too big. I have read articles in magazines covering the subject. It > works best with a controllable pitch propeller. I have the hardware to do > it at anchor in the rare strong enough current but have not found the > round-tuit to finish that project. > > > 2. Imagine dumping a bucket of seawater over your new invention. At sea, > eventually every place that can get salty will get salty. Sure. All things electric would be enclosed. Navy ships are almost nothing BUT electronics nowdays, and they are VERY reliable, given what they do. Of course it is just a given that sooner or later failures will occur in ANY system, mechanical or electric, and so redundancy, ease of repair, and expensive to fix must all be part of the equation. Since my system would use an off the shelf genset that could be mounted on rails anywhere, and all the other stuff is modular and easy to remove, I think my approach would actually be easier to work on. Engine malfunctioning? Hoist it out and throw it in the back of a pick up and take it down to the shop. Electric motor acting up? Un-bolt it and its power cables and take it in for testing or replace it, maybe one hour of work. I am not suggesting that there are no disadvantages to a hybrid drive on a boat, but I do think that with the way I want to do it the better fuel range, ability to get into and out of most if not all places using no fuel at all, flexibility of operation, and multi functioning of the system for many applications makes such a set up inherently more efficient, more compact, lighter weight, and cheaper than the traditional set up, IF it is done properly. -Ken _______________________________________________ Liveaboard mailing list Liveaboard@liveaboardnow.org To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [EMAIL PROTECTED] To unsubscribe send an email to [EMAIL PROTECTED] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/liveaboard@liveaboardnow.org The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
