Diesel Electric Propulsion

[Hyprdrv]

Ranger,
For an 800AH pack for your house bank you would need 16 180AH LP's. There is a quite long string on LP's for a house bank here at CF. Some very good info if you can wade through it all. Most of the manufactures batteries are actually more than their rated AH so with a 180AH battery you might get 190AH or more but never less. I'm not planning at this time to convert my AGM house bank to LP's only because I plan on adding solar to charge those and my House Pack batteries are only a couple years old. A side note, my genset battery is separate from all else and the Alternator ONLY charges that. I don't believe in adding complications that arise from oversized pulleys and Alternators but that's a personal thing. If I ever have a problem with my Genset battery I can run jumpers to 15 other batteries until it starts. 8o)


Steve in Solomons MD
Lagoon 410 S2E

[Maine Sail]

I do think hybrid propulsion can work on boats but right now the box that it fits into may not work well for everyone.

Some thoughts on this having recently chartered a previously electric hybrid cat that was converted BACK to diesel.

The catamaran we just chartered was one of the much applauded hybrid fleet. To sum up the charter company owners comments; "It was a miserable failure.". Evidently it was so bad, the builder took it back and converted it back to a diesel powered vessel.

Apparently the engineers who told the owners they could do 4 hours before the 22kW hybrid genset would kick in had never heard of Peukert, the effect of the Caribbean heat on lead acid batteries etc. In short the huge 22kW genset ran almost continuously in order to run that boat...

According to the owner of the charter company the boat could barely make it to the outer Road Harbor buoy before the 22kW genset kicked in.

That original hybrid genset, which is still installed, was considerably louder than both Yanmar diesel propulsion engines at cruise RPM...

22kW is a lot of diesel and genset and noise. This was a factory engineered hybrid boat that was supposed to do 4+ hours on electric and it barely made 30 minutes when new and only got worse as the batteries aged in the Caribbean heat.

Consider that a genset, sized to power a hybrid propulsion system, may actually be louder than a diesel propulsion engine. It certainly was on the cat we just chartered...... The boat was great but the left-over 22kW hybrid genset was obnoxious... Food for thought....

[Hyprdrv]

Mainsail,
I'm assuming this was the Lagoon 420?
I did not buy my 410 cat new. in all 3 cases of the 410E's the original batteries provided by Lagoon crapped out in about 1 year. If you ask any Lagoon owners with any boat from Lagoon the house bank/engine Bats provided by them are junk. They are the same batteries that were provided for the 420E so they didn't last long. Add the fact that they were on a charter boat I'm surprised they got out of the harbor.
I know you know as well as I do that a system like I have is not for the inattentive market that most would fall into in the charter business. The "clients" don't want to have to think when on board and to make it worse, don't really care about things like batteries. In most cases the Charter Companies didn't understand the systems either so we have a system that was doomed to fail from the start. Lagoon had sold the 420 as the answer to charter boat nirvana. less fuel, less maintenance, and quite motoring. They were hit so hard in such a short time they offered to replace the system with the proven diesel system. Once the panic had hit the majority wasn't going to take a chance so switched back. As for the noise Im not sure what they used by my 16KW is In a sound enclosure up front and it's not that noticeable. I do like the new DC gensets though and would jump on one of those. The Db rating looks pretty good.


To sum it up Lagoon made a lot of mistakes and bailed. Several 420 owners who have upgraded their batteries to good AGM's are happy with their boats but concerned with the fallout from the negative press.


That's another plus for LP's, they are less effected by the heat and not at all by Peukert.


Steve in Solomons MD
Lagoon 410 S2E

[valhalla360]

Originally Posted by Hyprdrv

Hi Skip,
First off the Cat has a large face to weather above the decks so any direct windage dead on is going to have an effect on speed. In the conditions you mentioned I would probably do around 4-5 knots. With those conditions I would tend to tack instead and continue to sail as much as possible. I run into those conditions on the bay quite often and will hug the shore to lesson the sea state. The 410 came standard with 28HP diesels. Go to https://groups.yahoo.com/neo/groups/electricboats/info


and see what a few sailors with large Monos have done. These guys are doing it! Depending on where you are there are companies on both the east and west coasts that have done conversions or supplied equipment that could size the motors for you.


Don't forget that the Electrics have a lot more torque. Even at 9 tons I can get up to speed in a boat length and even come to a complete stop in that length. The real issue is selecting the prop (bigger and higher pitch) to maximize the motors. I run 18" props. And no folding ones. No regen if they fold up. I could care less about loosing a knot under sail when I'm above hull speed already
The story on the A/C was not mine but the owner of the first 410E "Waypoint" coming across the Atlantic. The Regen had fully charged the batteries so they had to "bleed of power. The real solution was to put the motors "slightly" in reverse so the regen wasn't working but they forgot to tell the owner that before they left.
First Electric Lagoon Crosses Atlantic to Annapolis...Then Heads to Tortola
Electric drive for Lagoon catamarans


The Generator and Regen go directly to the 144V bank then power is sent to the house bank through a charger (144V to 12V). I run a 6KW Inverter to go from 144V DC to 120V AC for the A/C system or any other 120V appliance (a hair drier comes to mind) at anchor. To reduce loads on the Propulsion bank I plan on 2 solar panels off the Davits. They don't make a controller (yet) to go to 144V plus I don't plan on covering the decks in SP's.


Steve in Solomons MD
Lagoon 410 S2E

This sounds like you are confirming what several of us have been saying.

Yes, you can do a hybrid system and it will work fine. The problem is it is more complicated and the up front price is higher for an equivilent system (this system is not equivilent to the standard diesels but if I remember correctly it was still more expensive)

The 12hp electric motors sound like they are putting out similar performance to what 12hp diesels would put out. With no wind on the nose, they can get you up to hull speed but there isn't enough HP to fight a strong head wind, so top speed drops quickly. Based on your statements, you are simply accepting the lower motoring performance. If you went with the standard 28hp diesels, you could probably maintain hull speed in those strong headwinds where you instead start tacking.

Everyone agreed instand torque would be good around the docks (ie: up to speed in a boat length) but once up to speed, HP in equals HP out.

Yes, newer generators are more efficent and using the high voltage DC helps also but it's still more efficent to hook the prop directly to the diesel.

Good info. Thanks for sharing.

[Hyprdrv]

No Valhala Electric motors do not put out the same HP as diesels, or 1 to 1. The common formula to somewhat equalize electric motors to diesels is 1 to 2.5 meaning for every 1 EHP you need 2.5 DHP do to efficiency of the Emotor. So my 12HP Emotor is equal to a 30HP Dmotor.
I've had this conversation before with my Nabors at the dock. A 40ft mono has a top speed of 8 knots which it seems is the typical speed of most boats of any size based on their motor size. If they hit a short steep wave of 4 feet with head winds their pretty much in the same range I am when I do the same. A "standard" diesel running at 2400 RPMs (typically their max) can throttle up higher but so could I. In my case the torque will remain the same with higher RPMs to the props giving me more speed but my limit is the Amp Draw from the batteries or genset. The genset is limited by it's max output of 110A or in actuality 80A do to limits of an overdraw safety switch. Electric motors are far more efficient than diesels across the board. As far as fighting head winds and waves we both loose something.


Complicated is subjective. My wife's sawing machine to me is complicated. 8O)


Steve in Solomons MD
Lagoon 410 S2E

[skipmac]

Hi Steve,

Thanks for the answers. My comments and further questions below.

Originally Posted by Hyprdrv

Hi Skip,
First off the Cat has a large face to weather above the decks so any direct windage dead on is going to have an effect on speed. In the conditions you mentioned I would probably do around 4-5 knots. With those conditions I would tend to tack instead and continue to sail as much as possible.

Sailing of course is always my preference (or I would have a trawler ) but having made a few trips to the USVI from south FL have determined that motor sailing will get you there in half the time it would take to tack 1000 miles.

I run into those conditions on the bay quite often and will hug the shore to lesson the sea state. The 410 came standard with 28HP diesels. Go to https://groups.yahoo.com/neo/groups/electricboats/info


and see what a few sailors with large Monos have done. These guys are doing it! Depending on where you are there are companies on both the east and west coasts that have done conversions or supplied equipment that could size the motors for you.

I know that it is doable and a few large monos have done so. However a couple of things.

Until recently there were no off the shelf systems that had a single electric motor big enough to push my boat in anything but a dead calm. I have now found a couple of companies supplying large motors BUT the cost is outrageous. I have posted this question on the forum several times and so far have gotten not a single response. Why does an electric motor for a boat cost many thousands of dollars, over $10,000 for some of the high power units when I can buy a continuous duty, high quality industrial motor for around $1,000? The electric motor for my wife's Prius, rated about 60 HP if I recall, is less than $1000.

Yes I understand the economy of scale, marine rating yadayadayada but that does not justify a price increase by a factor of ten.

That is also part of the other main objection that needs to be overcome to make electric feasible, the overall cost. After the cost of the overpriced motor and adding a large diesel genset to give you the cruising range, an electric system will cost 2-3 times more than a complete new engine and transmission. That for me is really hard to justify.


Don't forget that the Electrics have a lot more torque. Even at 9 tons I can get up to speed in a boat length and even come to a complete stop in that length. The real issue is selecting the prop (bigger and higher pitch) to maximize the motors. I run 18" props. And no folding ones. No regen if they fold up. I could care less about loosing a knot under sail when I'm above hull speed already

In my situation I am not really very interested in the regen capabilities. To really benefit from regen I think one needs significant battery capacity to store the power. However when adding a large generator to get the extended cruising range and a large battery bank as well the weight and space will become an issue.


The story on the A/C was not mine but the owner of the first 410E "Waypoint" coming across the Atlantic. The Regen had fully charged the batteries so they had to "bleed of power. The real solution was to put the motors "slightly" in reverse so the regen wasn't working but they forgot to tell the owner that before they left.
First Electric Lagoon Crosses Atlantic to Annapolis...Then Heads to Tortola
Electric drive for Lagoon catamarans

I have to confess that I am just a little skeptical that regen could power an air con system, at least full time. I think realistically it could take 3000 watts or so of regen to keep a boat size air con running. Does the regen in this system have that much capacity?


The Generator and Regen go directly to the 144V bank then power is sent to the house bank through a charger (144V to 12V). I run a 6KW Inverter to go from 144V DC to 120V AC for the A/C system or any other 120V appliance (a hair drier comes to mind) at anchor. To reduce loads on the Propulsion bank I plan on 2 solar panels off the Davits. They don't make a controller (yet) to go to 144V plus I don't plan on covering the decks in SP's.


Steve in Solomons MD
Lagoon 410 S2E

[Hyprdrv]

Skip, Your last comment on the regen. I didn't word that correctly. The regen had charged the batteries full on it's own so to bleed some power off they ran the A/C until the power was down to continue regen. The regen wasn't what was powering the A/C, the batteries were. You see on electric DC motors whenever the prop is spinning the motor turns into a generator so you leave the motors on all the time your out and about. Brings up an interesting question about whether your under sail or power if you come across a another boat sometimes. I always give right of way. By putting them into a slight reverse it shut off the regen. Something that wasn't in the manual. Regen doesn't amount to much unless your traveling for a few days straight with real good wind and speed.


Sorry about the confusion,


Steve in Solomons MD
Lagoon 410 S2E

[valhalla360]

Originally Posted by Hyprdrv

No Valhala Electric motors do not put out the same HP as diesels, or 1 to 1. The common formula to somewhat equalize electric motors to diesels is 1 to 2.5 meaning for every 1 EHP you need 2.5 DHP do to efficiency of the Emotor. So my 12HP Emotor is equal to a 30HP Dmotor.
I've had this conversation before with my Nabors at the dock. A 40ft mono has a top speed of 8 knots which it seems is the typical speed of most boats of any size based on their motor size. If they hit a short steep wave of 4 feet with head winds their pretty much in the same range I am when I do the same. A "standard" diesel running at 2400 RPMs (typically their max) can throttle up higher but so could I. In my case the torque will remain the same with higher RPMs to the props giving me more speed but my limit is the Amp Draw from the batteries or genset. The genset is limited by it's max output of 110A or in actuality 80A do to limits of an overdraw safety switch. Electric motors are far more efficient than diesels across the board. As far as fighting head winds and waves we both loose something.


Complicated is subjective. My wife's sawing machine to me is complicated. 8O)


Steve in Solomons MD
Lagoon 410 S2E

Please enlighten us. This subject was already discussed a few pages back and no one came up with an explaination for how electric motors break the laws of physics.

HP is HP. It is defined the same regardless of where power is derived from. Saying it's complicated is dodging the question. HP is what determines cruising and top speed. The instant torque from zero RPM will result in better acceleration but it won't get you to a higher speed.

The closest someone came was the ability to use larger propellers but to achieve any significant increase in efficency would require masive propellers and you could achieve the same effect with a diesel by running it thru a reduction gear to boost the torque and turn the same giant propellers. Even with massive propellers, you aren't going to get anything close to 2.5 times the efficency.

I believe you are confusing hull speed with electric motors having some special ability. In calm conditions, it doesn't take a lot of power to get a boat up to hull speed. Most boats are outfitted with more HP than is needed to reach hull speed but when you try to do hull speed and fight a strong headwind you need that extra HP if you expect to maintain hull speed or punch thru waves. The standard approach with early electric powered boats is to keep costs down by accepting that you won't be able to maintain hull speed. You could achieve the same thing by outfitting 12hp diesels.

I am happy to learn. On another thread I was corrected on my understanding of how GPS calcualtes speed and I learned from it. If I am missing something, I would open to learning but so far no one has come up with an explaination and your description fits perfectly with the limitations of a hybrid system runnng smaller HP motors.

[Hyprdrv]

You would have to look at how HP ratings are derived. Hp for fuel burning motors are rated differently than electric motors is what I am saying. The standard conversion for the 2 types is 2.67 to be exact.

One hp = 0.746 Kw. A Dyno engine Hp is usually a brake-horsepower rating, while an electric motor Hp rating is output HP.


This might help.


Horsepower vs. Torque

[Juniper]

No Valhala Electric motors do not put out the same HP as diesels, or 1 to 1. The common formula to somewhat equalize electric motors to diesels is 1 to 2.5 meaning for every 1 EHP you need 2.5 DHP do to efficiency of the Emotor. So my 12HP Emotor is equal to a 30HP Dmotor.


Electric drive motors have more then one HP rating, a max HP, 30 sec rating, 5 minute rating, continuos rating,
I have a 2.3 HP GE shunt motor that can handle 300 amps at 36 volts 10+ KW or 14 HP, it can do that for 30 seconds then it trips an interal temperture switch, otherwise it would burn its self up, it will go at about 5 HP for about half an hour.
So your 12 HP Emotor could possibly crank out 50-60 HP for a short time, Emergency stop/start. the controller has to be able to handle it too. and you run into Purket.
BHP for electric is different the infernal combustion engines, with electric as rpm goes down torque goes up, ICE rpm goes down torque goes down too.

[Arthur Garfield]

Hp is Hp
Watts are watts
Kw are Kw

"eHp" are Hp generated by electric though are still equal in force/power to mechanically generated Hp.

There is the conversion ratio difference of KW to Hp.
1 hp = 0.745699872 kilowatts
1 kilowatt = 1.34102209 hp
A person is able to talk themselves into anything !
Any talk of "eHp" somehow more powerful than Hp is entirely magical thinking !

I am all for "Ep" but ICE/carbon fuels still rule but not for much longer.



All the Best

[Seaguy]

Originally Posted by Hyprdrv

So you have 2 diesel motors to spin your props and a Genset on board. Those 2 motors are going to double the fuel used plus the wife wants that hair drier running so you need the Genset on every so often. How is that more efficient?


So let's look at generators for a second. The new ones are lighter and much more efficient than mine is but it still weighs less than the 2 motors and sail drives your boat will have. I can carry the electric motors out on my own (about 120# each) by the way. So let's just say it's a 300# savings at this point. You have to maintain 3 motors were I have 2 of the 3 that require checking the torque on the connecting wires once a year and replacing 2 shaft bearings (at a cost of $20) every 300,000 hours of run time. No my fingers didn't stutter.


One last note because you mentioned your boat was a "performance" cat.
Didn't Gunboat select Electric Drives for their 60' cat? Pretty much the same system I have onboard EG.


Steve in Solomons MD
Lagoon 410 S2E

Don't want to start a long drawn out discussion, but the diesel engines will use less fuel for the same power. You seem to be ignoring the simple fact that when you burn diesel in a generator to create electricity and then store and reuse that electricity to drive a motor, there are significant inefficiencies. The best generators are around 98% efficient and the best mid sized electric motors (less than 50HP) are around 90% efficient. So you end up with .90*.98 or about 88% efficiency or 12% loss relative to driving a propeller directly. Doesn't matter how light your generator is, the diesel engine would be more efficiently used to drive a prop. And this doesn't include the added weight and cost of the electric motors and batteries.

I do not have a genset, just two Yanmars -- YM30s with 160Amp alternators at around 350 lbs each including cooling system.

A new 8kW generator weighs about 350 lbs. And say you get your two 8kW electric motors and batteries to come in at around 350lbs (this would be minimal batteries). You now have a system that weighs the same yet you will burn more fuel for same power, have significantly less max power and anything more than 1/2 power will be available for a very limited duration (as the 8kW generator will only give you 1/2 power to 2 motors or full power to one). And your system is totally reliant on a single diesel generator. Solar panels can help the system but since the panels generate a small % of power needed, it only helps if you aren't using your engine much (which is a common scenario).

Gunboat offers hybrid options but most buyers choose all diesel. Gunboat is very clear with the limitations of the hybrid option.

But hybrid systems do work and I'm glad you are happy with yours.

[Hyprdrv]

Arthur you are correct!
We really shouldn't be using the term HP for the differences but we were comparing replacements for the 2 and I stand by the 2.5 as the number to replace an Emotor for the Deisel in HP.


"Horsepower is a misleading term, especially in marine engines. A diesel's horsepower rating is not a measured quantity, but a calculated one. It only applies at a specific rpm, usually around 2500-2800 for a typical marine diesel. At the low rpm used during most sailboat operations, actual diesel horsepower is much less than advertised. More importantly, diesel torque is much less as well."


Torque is what turns the propeller, not horsepower. Torque is the twisting or rotary force applied to a shaft. It's measured as a force pushing at a fixed distance on a lever attached at right angles to the motor shaft. In the English system, force is expressed in pounds and the distance is a foot, so the torque unit is the pound-foot (not foot-pound, which is work.) In the metric system, force is in Newtons and the distance is one meter, so the torque unit is the Newton-meter.

When an engine is tested in the laboratory on a dynamometer, torque is the quantity actually measured. Horsepower is then calculated by multiplying the torque in pound-feet by the rpm and then dividing by 5,252. (For the derivation of the formula, see "Mechanical horsepower" and "Relationship with torque" in this Wikipedia article.)


Steve in Solomons MD
Lagoon 410 S2E

[valhalla360]

Originally Posted by Hyprdrv

You would have to look at how HP ratings are derived. Hp for fuel burning motors are rated differently than electric motors is what I am saying. The standard conversion for the 2 types is 2.67 to be exact.

One hp = 0.746 Kw. A Dyno engine Hp is usually a brake-horsepower rating, while an electric motor Hp rating is output HP.

This might help.

Horsepower vs. Torque

Nothing new there. Good analysis but incorrect conclusion.

This description explains why smaller electric motors work well in cars. Your typical compact car only needs 30-50hp to maintain freeway speeds but the 0-60mph times would be horrific. They put in somewhere areound 100-120hp make up for the fact that at idle the engine is only putting out a small fraction of the rated HP and torque.

With a displacement boat, no one really cares about the 0-6kts time and in a docking situation too much power is downright scary (I've seen power boaters get throttle happy while docking and it's not a good thing, saw a lady get thrown off the bow once). The diesel powered boats set up the drivetrain so that the motor is humming along at an ideal output when at hull speed so there is no significant HP difference and the torque is right up there also at cruise speed.

[valhalla360]

Originally Posted by Juniper

No Valhala Electric motors do not put out the same HP as diesels, or 1 to 1. The common formula to somewhat equalize electric motors to diesels is 1 to 2.5 meaning for every 1 EHP you need 2.5 DHP do to efficiency of the Emotor. So my 12HP Emotor is equal to a 30HP Dmotor.


Electric drive motors have more then one HP rating, a max HP, 30 sec rating, 5 minute rating, continuos rating,
I have a 2.3 HP GE shunt motor that can handle 300 amps at 36 volts 10+ KW or 14 HP, it can do that for 30 seconds then it trips an interal temperture switch, otherwise it would burn its self up, it will go at about 5 HP for about half an hour.
So your 12 HP Emotor could possibly crank out 50-60 HP for a short time, Emergency stop/start. the controller has to be able to handle it too. and you run into Purket.
BHP for electric is different the infernal combustion engines, with electric as rpm goes down torque goes up, ICE rpm goes down torque goes down too.

That's like saying you can strap a turbo on the diesel and pump crazy boost and you will take a 40hp motor up to 120hp. The motor won't last long but you could do it.

In a cruising situaiton where you are fighting a strong headwind and waves, it's unlikely 30 sec or 5 min will do much for you, so it's about as useful as keeping a turbo in the spares kit in case you need more power.