Electric ala Rube Goldberg

Discussion in 'Hybrid' started by Justaguy, Dec 24, 2015.

  1. Justaguy
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    Justaguy Junior Member

    Hi and Happy Holidays to all,

    Today seems to be the day for "electric" topics. Though similar in some ways to the new "current wisdom on electric" thread, didn't want to hijack it, so started a new thread. I understand that my knowledge and presentation here are oversimplified. I'd appreciate any thoughts.

    Background: I'm considering DIY electric propulsion options for a decidedly DIY plywood boatbuilding project (box sailing barge, triloboat, etc). My motivations for considering electric are environmental and compatibility with the planned electric "ecosystem" on the boat (solar, battery bank, generator, etc). If I'm going to have to drop this idea, and stick with the standard gas outboard, I want that to happen based on solid reasons vs. "we don't normally do this".

    Concern: I've only seen reasonable installed electric systems on high-dollar boats or similar retrofits (example -- http://en.wikipedia.org/wiki/File:"e-Tolly"_bildge,_a_1973_Tollycraft_Electric_Retrofit.jpg). If that is a permanent limitation, it would be a show-stopper for a low-budget DIY build.

    My overall idea:
    12,000 lbs displacement hull with speed in the 5-8kt range. If high speed is not a goal (and it isn’t for me), I am intrigued by the combination of an ordinary industrial electric motor (large shop tool type – table saw, etc. or larger), solar power, and gas-powered electric generator. My reasoning goes like this:

    * If I buy a normal gas outboard motor, it would work if correctly installed. However, that motor could only propel the boat, and in a perfect set-up, provide a little power to the battery bank via its alternator. For simplicity, my conclusion: “propulsion only – non-maximized option”.

    * Electric outboard motors have the same limitation as above, plus they are exorbitantly expensive; $ to power ratio all wrong. Plus, won't get rid of the shaft length problem (undescribed here). My conclusion: “too expensive – infeasible option”.

    * If I buy a normal gas-powered electric generator (Honda-type used in construction / marine applications), now things get interesting. The generator would be more easily portable (reusable in other situations), could be used for many onboard purposes: appliances, tools, charge battery bank, and propulsion, if I use a suitable electric motor. Likely installed as inboard/outboard. The cost might end up being equal to one of the other options, but even if so, the utility would be much higher. My conclusion: “multi-purpose – maximized option”. So, this option seems best (most "overall liveaboard" bang for the buck), if it can be done well.

    While details are always appreciated, I especially needed generalized comments about the overall concept (knee bone connected to the shin bone, shin bone ...)

    Thanks.
     
  2. FAST FRED
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    FAST FRED Senior Member

    The simplest option would be a large prop deep gear reduction OB that will push the boat

    AND the Honda for house and other service.

    Not sexy, but practical with zero experimental risk.
     
  3. cmckesson
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    cmckesson Naval Architect

    My system is the "electric generator" option. I was motivated by early impressions of cruising when I was 12 years old: My observation was that we ran the yacht's diesel as much to charge the batteries as we did to drive the vessel. So I thought "What if, instead of a propulsion engine that can 'oh by the way' charge the batteries, what if I had a battery charging system that can 'oh by the way' propel the boat?"

    My current system is a re-purposed golf cart motor, lead acid batteries, and a Honda eu3000is genset. Features I like include that no single component weighs more than I can easily pick up. And that a change of any one component (e.g. when I replaced the previous rube goldberg generator with the Honda) was as simple as unplugging the shore power cable and pitching the old unit onto the pier.

    Drawback is of course range/speed, as the other fellows are belaboring in the other thread.

    We've been electric since 2000. Have taken the boat from Canada to Mexico. Have no regrets.

    Chris McKesson
     
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  4. FAST FRED
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    FAST FRED Senior Member

    Of course the other option could be to toss the high draw house items on the pier like refrigeration.

    Example,,DC fridges need about 100AH a day.

    A propane reefer requires a 20# bottle every 6 weeks or so.
     
  5. Justaguy
    Joined: Nov 2015
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    Justaguy Junior Member

    Good info.

    My thought exactly!


    A few questions please:
    1. Type of boat / displacement?
    2. Is your generator (or could it be) in a separate ventilated, but insulated well to reduce the sound?
    3. Is your golf cart motor simply connected to a straight shaft through the hull?
    4. In the simplest terms, what component gives you variable speed and reverse?
     
  6. philSweet
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    philSweet Senior Member

    re #2. No, that is against regs. A portable genset must be on the deck, and not permanently mounted. No fuel system mods to draw from tanks. No electrical mods to bypass the plugs. You can put it in a box on the deck, but a well in the deck would most likely be considered a permanent mount. Routing the portable genset output to the boat's shore power connection is arguably the best approach. The layout of the boat's electrical system should take this into consideration. A 3' pigtail is better than having a 30' shore cord strung across the deck. The Honda 3000 is really marginal for a/c though. I think there is one marine portable a/c that can run off the small portable inverter style generators. A pair of e2000's bridged gives you a bit more headroom, and would give you about 3200 watts of cruise power. Considering golfcart controllers run around 15kw, you might want the extra oomph.
     
  7. cmckesson
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    cmckesson Naval Architect

    The yacht is a 1968 Columbia 36. 17,000 lbs according to the travelift gauge.

    I previously had a Honda 2000 which was installed inside a deck box (for additional noise attenuation.) The 3000 is actually 3 dB quieter than the 2000, so I have it on deck exposed (except when its canvas cover is on.) I know of no regulation for recreational boats that limits your ability to mount the generator below decks, but I consider gasoline belowdecks to be imprudent. (Ironically, I am comfortable with propane for cooking and heating.)

    The challenge with the shafting installation is to find a place for the thrust bearing. Since I already had a F-N-R gearbox with internal thrust bearing, the simplest solution was to retain it. So no, my motor is couple to a gearbox, and the direction control is via the gearbox.

    Speed control is via an ALLTRAX 300 Amp DC controller. It works just fine. The critical failure-prone component was the $0.99 potentiometer used as a throttle, but I replaced that with a MILSPEC pot about ten years ago and have had no trouble.

    The battery bank is one-deep in Trojan Group 31 size industrial (floor polisher) batteries. Each of six 12V batteries is ~120 Ah (20hr rating), thus I carry about 10 kWh of stored power. This battery battery bank supplies the ship's house loads as well (via a 72:12 DC:DC converterer.) I also have a small (300W) 110 VAC inverter installed.

    We have an array of six solar panels (~50W each). In summer the solar panels will supply all of our normal needs. If we do need to steam for a long distance (which I try to avoid) then we will run the generator. Our normal cruise is 8 weeks in the waters of British Columbia, about 500 miles punctuated with some exciting rapids and tidal narrows that are better dealt with under power. In such a cruise we use about 5 - 10 gallons of gasoline.

    Now, for all the "it will never work" fellows, let me just admit that this is a SAILBOAT. We sail everywhere. We spend a lot of time at one or two knots waiting for the wind. We like it. We had no engine at all for many years. I finally installed the electric drive to eliminate the "joy" of drifting 100 yards outside the anchorage when the wind went flat...or worse still, paddling the boat that last mile! (smile) If you are impatient, then I fear you would be dissatisfied with the level of performance we have.

    All the best,

    Chris McKesson
     
  8. gonzo
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    gonzo Senior Member

    There are several regulations that forbid installing a portable generator below decks. There is no vent to the outside of the hull for the fuel fumes, the electrics are not spark proof, the exhaust is not vented outside, the exhaust does not have a proper heat shield.
     
  9. cmckesson
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    cmckesson Naval Architect

    I am interested in what you say Gonzo. Can you provide me with the citation for those regulations? I was looking in 46 CFR and not finding them, and that worries me - I don't like missing the rules.

    Thanks in advance.

    Chris
     
  10. cmckesson
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    cmckesson Naval Architect

    Still looking for regs on this subject, and the only ones I find are 46 CFR Subchapter C Subpart 25.35 about backfire flame control and 25.40-1 about venting the engine spaces.

    Note that I am asking about actual laws - requirements the violation of which can result in termination of voyage, and not guidelines or best practices. I fully agree with the suggestions about best practices.

    Err, just to be complete, I am also viewing this from the standpoint of my own boat, thus a US-flagged uninspected non-commercial non-passenger-carrying vessel constructed prior to 1969.

    Thanks again!

    Chris
     
  11. philSweet
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    philSweet Senior Member

    Edit.

    I just realized what you are probably doing. There are no regs covering portable generators. That's the point. But if you do any of the four things I mentioned, they then can be treated as an onboard generator which is subject to regulation.
     
  12. gonzo
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    gonzo Senior Member

  13. philSweet
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    philSweet Senior Member

    cmcK, while you are here, a couple more questions on your set up.

    With both solar and genset, and both 72Vdc and 12Vdc, how do you maintain the 12Vdc service. Is it always tied to the 72Vdc side with a dc/dc converter? Are there any batts dedicated to the 12Vdc side?

    Is your tranny direct driven or belted?

    Is your 72Vdc side fused for 300A, or something less?
     
  14. cmckesson
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    cmckesson Naval Architect

    Thank you both, that was helpful. Gonzo I see that 33 CFR 175.201 imposes upon the operator (not just the manufacturer) the duty of compliance with 33 CFR 183.6xx, that's good to know.

    Regarding the regs in 183.4xx, labeled "manufacturer requirements," do you interpret those as being mandatory for owner installed systems as well? I have seen a LOT of boats wherein the batteries are not held down to resist a vertical force of 90 lbs for one minute or more, and I have never had a boarding officer check such a feature on my own boat. (Again, I am not concerned about the wisdom or prudence of the matter, just about "the letter of the law.")

    Relevant to the present conversation are also the conductor sizing rules in 183.435. I'm in compliance with those, but I am not in compliance with the rule to have a plastic cap on each of the battery terminals (183.445), and the 200 Amp fuse on the propulsion circuit is more than seven inches from the nearest battery...perhaps I'll look into improving these two items.

    Thanks again for the link.

    Chris
     

  15. gonzo
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    gonzo Senior Member

    If you use a regular battery tie-down strap or bar system, it will comply with the regulation.
     
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