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PmWiki /
AuxiliaryPropulsionElectric
Howard Ray 1506-16-2005 09:04 AM ET (US) I started building my (as yet unnamed) Eun Mara in September 2003 and am now nearing completion. The spars are the major component left to do. Mine has the inboard rudder option and no motor well. I plan to rig a temporary thwart across the stern with an electric motor on the outboard end to use for power when necessary. Alec Percival 2806-24-2005 04:54 AM ET (US) Speaking of bouyancy, Ive just finished a 12 electric boat and used lots of those childrens pool "noodles " cut up as flotation. Richard Almond 31709-18-2006 07:18 AM ET (US) Now here's a thought to throw open to discussion (and I'll be surprised if nobody else has considered it) - electric propulsion. The lake here in Canberra is quite small, with notoriously variable winds (due to surrounding hills, I assume), and I can see that when Skerry is eventually in the water I might well end up using her largely as a motor boat when I'm using her locally. I don't want to have huge banks of batteries, and wonder whether I could rig up a "petrol-electric" system (akin to a diesel-electic locomotive). In other words, I could have a smallish battery with enough capacity to run the motor for 30 minutes or so (enough for berthing maneuvers when we are actually sailing), but with a small portable generator on-board which could be used to keep the battery charged while doing more serious motoring. (The type of generator that springs to mind is the sort of thing that might be used for camping.) The propulsion unit might be in a "pod" form that bolts on to the outside of the hull, thereby avoiding the need for an outboard well. Advantages:
One downside I assume would be cost, but maybe not so bad if I don't include the cost of the generator, which would have uses other than for boating. This is just a thought at this stage, and any comments would be appreciated!!! DaleH 31809-18-2006 11:59 PM ET (US) As far as electric propulsion goes, have you seen: http://re-e-power.com/? I'm sure it's quite possible but the thing that finally made me go with an outboard (yes, I thought about it) is the feeling that electric power is still too "young" for my tastes. Let us know how it goes for you. Ian Milne 31909-19-2006 02:46 AM ET (US) Those E-pods are interesting! I remember that "Adagio", which isn't on the web now, had an electric trolling motor which fitted in the cockpit locker when not in use, and Howard's Eun Mara was going to have one on a bracket over the side, presumably also in the cockpit locker when not in use. Alan Hosler 32009-19-2006 07:56 PM ET (US) Richard: Regarding your idea for gas-electric propulsion you may want to read an article by Steve Graham in Water Craft (Jan/Feb 2006, No. 55). It describes work being done by Graeme Hawksley on a hybrid diesel-electric system. While his work is on a much larger scale, both physically and technically, than what you would want for your Eun Mara he still has some interesting ideas to share about this type of a system. Also, Steve included the following in his list of contacts which I found interesting: http://electric-boat-association.org.uk/ I was wondering, however, where you would place the gas powered generator. alec Percival 32109-20-2006 08:16 PM ET (US) Richard, I've been through this with a good friend of mine who is also an electronics engineer and it's very marginal. As a way of getting on the water prior to the launch of the "Heather-Mary" I installed a 56lb thrust electric motor into a 12' launch thatI rebuilt from a discarded hull.I dismantled the brand new motor (scary) and fitted the drive unit in a pod that i had moulded into the new keel. the switch gear was wired up to the cockpit. It works really well but i'm carrying around 4x 56 ampere batteries. One of the main problems is actually finding specs for these motors so it turned out to be a fast track build and try again sort of a project. I finally found from the Web that the motor drew 3.6 amps at full throttle. What they didn't tell you was that was "in air" which is very useful in a water craft. In fact the motor draws some 28 amps under full load. The little generators that you are looking at produce ac current and you would need to convert this to dc, I don't think it would produce enough current. Ihave a good book called living with 12 volt power which youre welcome to borrow. Dick Whitfield from the club is a good source of info as well. I seriously considered a Lynch motor for the H M but the switch gear required cost more than the motor which 5 years ago was over $4000. Sorry for being so long winded but it really is a very tricky undertaking. Richard Almond 32309-21-2006 03:58 AM ET (US) Thanks to all who provided feedback re' electric power (just about all our regular contributors, I think. It must be an option everyone has though of). However, I think it would be too costly to do it properly so I doubt that I'll pursue the matter further. Dale, yes, those pods from re-e-power are just the sort of thing I was thinking of, but expensive by the time you factor in batteries and my small generator idea. As you say, the technology is evolving. I think I'll just defer committing to an outboard well for as long as possible in the hope that something affordable appears! Alan, I have had a short e-mail correspondence with the UK people and am waiting for some information to come in the mail. Where to put the generator? Not sure, but I'm sure I could think of somewhere. It would not be a permanent fixture, so even just a shallow tray (to stop it slipping around) on the foredeck could be an option. Alec, that's all really interesting. Clearly I'd have to do a lot more homework if I were to get serious about electric power. As it stands at the moment I think that price will put me off putting too much time into investigating further - it just doesn't sound like a go-er. I haven't talked seriously with people at the club (don't get to many meetings at the moment). Did you know that Nigel Cox has fitted an electric motor inside the rudder of his catboat? He extracted it from an old outboard and it seems to move him around very nicely when he's not sailing. (For everyone else's information, "the club" is the Traditional Boat Squadron, based here in Canberra, of which Alec and I are both members.) DaleH 32409-23-2006 11:39 AM ET (US) Richard, I have been involved with radio controlled airplanes for 30 years and the change in electric powered airplanes are an interesting example of power source evolution. Not too long ago it was all NiCads especially the sub C sizes from Sanyo. A battery pack could weigh a few pounds in the larger configurations. Today, thanks to the LiPo technology (cell phones and laptops) we have way more capacity (several times more in some applications) and the packs weigh only a few ounces. Yes, there are new concerns and hazards, but with proper care, these packs are amazing. I think the development of electric and hybrid vehicles will push the development of these full sized systems fairly quickly, perhaps in only a few years. One day we may all be running fuel cel power systems on our boats- I wouldn't rule anything out. Bob L 32510-08-2006 10:36 PM ET (US) Hi Everyone, we have just returned from 4 weeks away, and interesting to read all about the electric propulsion debate. I had thought about it with batteries mounted low as part of the ballast, but at a remote location the thought of recharging batteries V simply refilling a can of petrol, turned me right off. Interesting to think of a generator though, so thanks everyone, nothing ventured, nothing gained. Paul Frederiksen 34411-05-2006 12:43 AM ET (US) Richard, You brought up electric propulsion about six weeks ago so I thought I would mention that Adagio's auxilary power is electric. It has advantages and disadvantages. If you like I can go into further detail, just let me know. Paul Frederiksen 34811-06-2006 11:42 PM ET (US) Richard, It all depends on what you intend to use your auxilary for. I sail primarily in the San Francisco bay, and on the numerous lakes in Northern California. Therefore I use aux power almost exclusively to navigate in and out of the marinas. I never see blue water and am always close to safe harbor. This is why I chose electric. After doing the math regarding battery weight, charging times, and available power, I concluded that I would be satisfied. However If I intended to go off-shore I would not consider it sufficient. Here is why. With Three large Marine cycle batteries, and the largest Minn Kota trolling motor (which produces 101 pounds of thrust), I am able to do just over 3 knots at full throttle... in calm water. With the sails down but heading into a twenty knot wind I can only do about 2 knots at full throttle. Battery life is just a bit over two hours at full throttle. As you can see, this is ok for what I need it for, but would be woefully insufficient to pull you off a lee shore in a wicked blow. My personal belief is that you should never sail into anything you can't sail out of and that this should preclude the need for an aux for anything other than emergency manuvering in tight marinas and the occasional puttering back in when the wind dies to dead calm and leaves you sitting out in the middle of the lake for three hours. The exact method I used for mounting my system is a variation of the outboard well idea. It is slick nearly invisible, totally silent and doesn't stink. These things were very important to me. I just couldn't see mucking up such a beautiful design with the ugliness of an outboard. I hope this is enough to get you started. If you need more details, don't hesitate to ask. Alan Hosler 36212-30-2006 11:40 PM ET (US) The Jan/Feb 2007 issue of Water Craft (No. 61) has four articles that will be of interest to some of the users of Dale's site. 1."Iain Oughtred's Work Ethic." As story about Iain including mention of his visit to the Wooden Boat Festival in Goolwa. The picture of his design office is interesting. 2 and 3. "Haiku - Poetry in Motion" and "Haiku - From the Keel Up." Haiku is an Oughtred-designed flat bottom; like an American sharpie. 4. "Strictly on the Quiet?" An article about electric outboards. |