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Diesel Electric Drive System
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Patrick Twohig
San Diego, CA
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April 29, 2014 - 12:57 am
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A few months back, before I bought my DE38, I was looking at the electric motor solutions provided by Elco Motor Yachts.  I was curious if anybody here had any experience with these systems.  I've been looking pretty hard at the system, but would need ot save up the cash and figure out a way to get the old Universal 5432 engine out of the boat.  ANybody have any thoughts on this?

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Scott Carle
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April 29, 2014 - 11:57 am
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I moved your post over to the engines forums πŸ™‚

 

sigh... an electric motor system is to me the holy grail πŸ™‚ I would love to be electric or diesel electric. The bottom line though is for a boat our size and weight it is really cost prohibitive and hard energy density wise to put in an electric motor and power supply (ie battery bank) big enough to give enough power for a reasonable duration. Boats in the 30 ft range and under are now doing this both semi economically and with reasonable power levels. Jumping from a 6 to 9 thousand lb boat to a 20,000 lb boat creates a lot of problems scaling the power up.

 

Options are

  • straight up electric with a battery bank to power it. Disadvantages are how to charge it and power density. You can get an hour to 4 or 5 hours of motoring out of this system depending on if you go with low density but much cheaper lead acid batteries or with Lithium batteries. Charging needs a shore charger or generator. Large solar array would work but probably take a couple days to fully charge in ideal conditions.
  • Diesel Electric is the most usable solution... for our boats though you would need a 12 to 20 kilowatt generator and a massive 30 to 40 hp continues duty electric motor plus all the attendant controllers and such. You could run off smaller battery bank for moving around the harbor  and use the diesel generator for longer distance motoring. In effect you will have to put in the diesel engine and the electric system. This should give you a little better fuel economy over the long run I think but I doubt you would recoup the initial investment over just having a setup like we have now.
  • Auxilary electric.. I think this is the most practical alternative. You have your currant engine and setup and add a smaller 10 hp or so motor on a clutch that can turn the existing shaft and prop when the engine is in neutral. A reasonable battery bank and you can cruise for hours a half of hull speed and maneuver around the harbor all day long under electric but for hull speed long distance you can use your engine. You might also be able to run the electric motor as a powerful generator to charge the battery bank while motoring.
  • true auxiliary electric. You have a big battery bank and and smaller electric motor able to push you 3 knots or so for close in and harbor maneuvering and to give you a little push when sailing in light air. Otherwise you sail like you have no engine at all. πŸ™‚

so the elco system.. looking at the ep-2000 which would be the motor I would choose. Your cost for straight electric would push 18 grand or so between motor, controllers, chargers and batteries..  Adding the hybrid option would bump you to about 30 grand. [Image Can Not Be Found] however based on their numbers, and I think they are probably realistic on our hull, with our 90 gallon fuel tank you would have a range under power of about 1500 nm at around 5 knots. πŸ™‚ my estimates of cost don't include installation unless their pricing on the website already includes that which I think is not likely[Image Can Not Be Found]

 

If your handy and put together your own system you could probably do close to the same system pieced together for about 13 to 15 grand for electric motor, batteries and generator. Still pretty damn pricey.

 

I would love to see it done though, so we are all waiting on you to do it first and let us know how well it works [Image Can Not Be Found]

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Scott Carle DE38 Cutter s/v Valkyr
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Patrick Twohig
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April 30, 2014 - 1:06 am
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The MSRP for the EP-2000 is still $8k according to the Elco site, plus the recommend a Fischer Panda 5kw marine electric generator to power the system.  I see used generators on ebay in the 5kw range that seem to foot the bill so I think if you wanted to be thrifty it's possible to get away with spending less money.  The sales guy recommended the EP-2000 as well.  I originally thought I would have needed one up.  My original engine is a 5432, so that's not that large.  I've seen lots of boats in that size fitted with 50HP engines.  For whatever it's worth, when I really punched the throttle hard on my boat she only got to 6 knots, I couldn't get her to hull speed on the engine alone.  Of course, given my boat's history I wasn't about to push things.

 

I don't know that the costs would total $30k, though for the hybrid.  The system's price on the site is $9k, plust $2k for batteries.  A brand new 5kw genset on eBay shows a price of $6000 and used ones are less.  I don't see that adding up to $30k honestly, unless I'm missing something.  The Elco sales guy said I could just buy a Honda generator and "just add it", though that seems like ghetto rigging a generator that's not designed for marine use.

 

Something still doesn't add up to me because if the motor is rated for 20 HP (max) that's ~15,000 watts.  How does a 5kw generator power that system.  Even at half the engine's rated capacity 5kw isn't going to cut it for continuous operation.  Though, I assume it's still practical if you can go 1500nm before you totally drain your bank.  You're still looking at a cruising distance that beats out a straight diesel drive.  I'm not sure how I feel about a parallel add-on drive system.  I wouldn't see much value in adding that in addition to the engine that's there.

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Scott Carle
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April 30, 2014 - 12:38 pm
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They play with numbers... those generators will not be able to run the electric motor at full throttle

20hp electric is what..... 14,800 watts so no it won't push you to hull speed on a 4000 watt generator. However it might get you to 5 knots. Or maybe to close to hull speed in flat water with no headwind. Our boats are real easy to push through the water. If you ever notice under power how little wake we create, this shows how little resistance through the water our hull form is giving us.

 

Of course that 20 hp number they are throwing out isn't the actually output of their motor. Actually their motor is putting out less than that. That number is their equivalency number to a diesel engine hp. The big difference is torque.. We normally never run our motors wide open, max rpm.. which is where our hp rating comes from. We can create a lot of torque with a electric motor at much lower actual HP which allows us to swing a bigger prop which increases efficiency greatly.

 

I could probably explain it a bit better than that, as this is a rough analogy, but my brain is hurting and I just don't feel like being that intelligent right this moment πŸ™‚ lol.  I swear once in a while... well every decade or so... I might rise to feeling smart πŸ™‚

 

as to the prices.. I just used there prices on the site and then added 30% for labor. You definitely could do it for much cheaper. Actually look at http://www.electricyacht.com .. I think they are pretty comparable.. hmm pricing for same size unit is about the same. Their smaller kits up to 12000 lbs displacement are under 3000 for the motor kit. They have a kit for 5 grand range to add an 8 kilowatt system to your existing motor between the transmission and the prop shaft. They say it only needs 4 inches of clearance between the tranny and the stuffing box.

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Scott Carle DE38 Cutter s/v Valkyr
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Patrick Twohig
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May 1, 2014 - 2:33 am
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20hp electric is what….. 14,800 watts so no it won't push you to hull speed on a 4000 watt generator. However it might get you to 5 knots. Or maybe to close to hull speed in flat water with no headwind. Our boats are real easy to push through the water. If you ever notice under power how little wake we create, this shows how little resistance through the water our hull form is giving us.

20 hp is ~14.9 kw.  Elco claims to have only an 8% power loss after the DC to AC conversion and leveraging only the "useful" AC power.  So that means that that the power draw is something like 16kw.  With a 5kw generator it is true that your propulsion batteries are operating at a net loss, but so long as the net loss allows the range meet or exceed the cruising range of the direct drive diesel system then it is still a viable solution.  Even at that, though the maths still don't make sense.

One thing I do like about the Elco vs hte Electric Yacht product is that the Elco is actually a sealed all-in-one unit with the motor control integrated.  The Elco motor is rated to run, even if the engine itself is partially submerged.

In case you're curious this is my engine running in forward.  This is at low RPMs and you can hear the gear clang: https://www.dropbox.com/s/jvrcqcnet191j9f/2014-04-25%2018.27.42.mp4

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Scott Carle
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May 1, 2014 - 8:29 am
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hmm.. yeah that doesn't sound good... engine itself doesn't sound bad.. maybe adjust the valves.. They sound a little lose but that rattling/clang isn't good.. maybe something just needs to be serviced in it.? I don't know a lot about transmissions other than the general idea of what they do though. I also know I would want to find someone really reputable to look at it as lots of mechanics will just tell you "oh you need to replace it" when it could just be a simple adjustment.

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Scott Carle DE38 Cutter s/v Valkyr
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Patrick Twohig
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May 2, 2014 - 11:01 pm
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From what I understand the gear clatter happens when the prop is momentarily spinning faster than the engine is, and then the engine catches up or the prop slows down.  Between the flywheel, torque characteristics of the engine, and some fluid mechanics it just happens.  At low RPMs it's not damaging to the transmission at all but makes a nasty sound.  I guess there's what's called a dampening bearing that is springloaded and acts as a slight buffer between the transmission and the prop.  When that starts to have issues you get gear clatter.

 

I just wondered if anybody else had that issue and if that is definitely gear clatter caused by a bad dampening bearing, or if it's something else.

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Scott Carle
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May 3, 2014 - 11:23 am
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Hopefully someone else here will know.. other than that you might try one of the boat forums that are focused on engines and transmissions.. I think one is iboat? I know when looking for parts for outboards and my universal that I have run across them a few times and people were answering questions there. If you hear something on one of them let us know here πŸ™‚

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Scott Carle DE38 Cutter s/v Valkyr
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Patrick Twohig
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May 3, 2014 - 3:37 pm
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I've heard of people pulling the gearbox by loosening the aft engine mounts, disconnecting the drive shaft coupling, and then using a winch to gently raise the engine up to undo the bell housing nuts.  From there you can just pull the entire gearbox, transmission, and dampening coupler and throw it on the workbench for a complete rebuild.

I'm just worried about doing that and having the prop fall out of the back of the boat, knowing my luck.

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Scott Carle
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May 3, 2014 - 9:43 pm
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I don't think you can get the shaft on our boats out to the rear without removing the rudder. Easiest way to do it would actually be to pull the engine up and pull the shaft forward and out. Mine would only move 8 or 9 inches before it hits the rudder. Actually there is only and exactly enough space between it and the rudder to get the prop between them to get it on and off the shaft.

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Scott Carle DE38 Cutter s/v Valkyr
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Patrick Twohig
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May 5, 2014 - 11:00 am
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Well.  I went to take the boat out yesterday and I finally killed it.  Stuck in reverse, linkage blew out 'cause I had to pull so hard trying to get out of gear.  Luckily we did this just before undoing all of our dock lines.

Scott, can you do me a favor and restore the images in this article: /info-index/engine/transmision-removal-guide

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