Is diesel-electric or all-electric the future?

[wingssail]

Originally Posted by Na Mara

...But to be honest all these calculations are making wonder whether I should just not bother with the repower. Why not just avoid using the 90hp Yanmar as much as possible, fit sufficient renewables to cover my power needs without relying on the engine, and stick with gas for cooking. Probably the embodied emissions in upgrading to diesel electric over what I have is likely not to be worth it even given the fuel savings, and I could do a really mean power and gas system upgrade for about 20000 euro.

One consideration which is not often addressed is the simplicity factor.

For us, as long distance (and long term) cruisers we opted for the most simple and most easily repairable overall system.

Breakdowns are a fact of life. On a cruising boat the owner/operator is often responsible for diagnosing and repairing whatever failed. The most simple system, the one with the fewest and most reliable components, and therefore requiring the fewest spares, is the one which I prefer. Either the diesel-electric or all electric have far more components and far fewer diagnostic tools than a simple straight diesel engine set-up.

Advocates of the all electric or diesel electric systems are optimistic to the point of foolishness if they think their complex systems which might (but not necessarily) run perfectly when new will continue to run perfectly for many years.

So we have opted for a simple, straight diesel engine, with electric refrigeration and gas cooking and otherwise very moderate electrical demands, a moderate 450AH battery and a couple of solar cells. Most of our engine use is for battery charging, but we carry 60 gallons of diesel fuel (surprisingly not stinky) and that provides at least 500 miles of motoring, if needed, and/or at least one month of total independence from shore or sunny days, should that happen.

That system is also the lightest possible system where moving significant extra weight has direct increased cost and dramatically reduced sailing performance, for anyone who cares about that.

So, for us at least, repowering to get away from diesel is contra indicated.

[merrydolphin]

To answer the question, just follow Uma on YouTube for a while. They have been successfully cruising all electric now for a good while. They of course had a learning curve. But now have a system that seems to work well. And no, they are not sailing a super modern hi-performance boat. They have a 1970’s vintage Pierson 36 very nicely tweaked out. They have cruised a good chunk of the world and have a re-genation system so that as they sail they are recharging their batteries. As well as solar. Now granted. They don’t motor unless they have to. So if you are not an avid sailor, it may not work, but they have proven that if you like to and are able to sail a lot it works and works well. They have even eliminated propane and have all electric galley. Fascinating channel and interesting people.

[noelex 77]

Originally Posted by merrydolphin

Now granted. They don’t motor unless they have to. So if you are not an avid sailor, it may not work, but they have proven that if you like to and are able to sail a lot it works and works well. They have even eliminated propane and have all electric galley. Fascinating channel and interesting people.

Keep in mind that their cruising is mostly marina hopping, where shore power is frequently used to replenish the battery bank. Many people prefer this style of sailing even if there are no power restrictions, but if you prefer long term anchoring I doubt if their system would work. The energy balance does not add up.

Still, they enjoy themselves . There are no rules; adopt the style of cruising that makes you happy.

[jojolimited]

Originally Posted by lightguy

My comment from the peanut gallery;
54' Alibi catamarans originally produced by design all electric propulsion systems in 2010.
These are performance cats not the big luxury ones.
Perhaps things have gotten more efficient but many owners have retired the electric motors and replaced with diesel engines. At considerable cost so there must be a good reason.
The one that is currently on the market has NO solar panels which I find quite odd in a boat originally intended to be all electric. Shore power charging or aux generator to provide electricity ??
One more consideration with a catamaran and especially a performance cat is weight.
I would assume "heavy" monohulls could absorb the additional weight penalty of big battery packs much better than that on cats where weight is an absolute killer of speed.

Funny you should mention that. Energy Observer is a converted racing cat. Relatively light weight compared to regular cats.

[Corvidae]

Uma is a great channel, they do show that a small generator would make life easier. Not that it's essential, but they do have to fight a lot more than if they could just flick on the motor. A small Honda could probably quadruple their motoring range at the least. Getting a generator the same size or larger kw as the original propulsion allows near the same performance with a VFD. It's basically replacing the transmission with an alternator/motor Using batteries it's more of a range extender, since you tend to get limited by battery charger size.

[Emoyeni]

Originally Posted by WhiteHill

“Jimmy, your concept may be right but it is premature......"
https://cornellsailing.com/2020/12/electric-shock/

I don’t understand why this guy didn’t add solar panels like everyone else?

[Hyprdrv]

Ok here we go again...
Lagoon 410 S2E Electric 41 ft. Cat, 1 of 3 built by Lagoon as a test bed for Electric Propulsion in 2004.
Twin 9kw Electric motors running at 144V
LiPo4 bank of 48 batteries
16KW genset capable of running the motors and charging the battery pack at 5 knots. Fuel burn is roughly 1g an hour. I have 40g of fuel on board.
Regen capable at speeds above 8 knots (sailing) but faster does it quicker.
Solar panels removes all house loads from propulsion pack. (2-260W panels) I haven't turned on the 144V to 12V charger since the panels where installed. This does NOT include AC systems which run through a 6KW inverter off the Propulsion Bank.

And of course shore power capable at 240V charging.

So the motors will eat 50A at 5 knots, the most efficient speed under electric power.
The genset is A/C rectified to 156V max which charges the batteries or/and runs the motors.

Located on the Chesapeake Bay we do 1 to 2 week long cruises and day sails. One of the sister boats is somewhere in South America and the second boat is coming back from the south of Florida outside, a trip made several times as well as doing the Carib. My boat sailed in the Carib for several years then brought to the bay. All 3 boats came over from Europe by way of the Atlantic.
The LiPo's have a life expectancy of 3000 discharges. That's fully charged to fully discharged. Since I have never discharged my batteries more than 50% then that gives me a life expectancy of, by my calcs of usage, my life time.
We motor into the river and then sail. If we have to run on electric we are good for around 25nm then run the genset. The only time the motors didn't meet our needs was during a Duratio (sp) of 75 knot winds. Anchor saved us that time.

You can do all the math you want but I wouldn't trade our system for a diesel any day. As far as boat value goes, more and more people are coming over to the "E" side. Two people on my dock are in the process of converting at this time. Back in 2010 I was here and got fed up with all the nay sayers who thought it would never work. At least at this point people are starting to look at "E" systems as an alternative.
NOT for everyone and do what you want.

Steve in Solomons, MD

[Corvidae]

What charger and motor controller are you using? I keep thinking about going to a 96 volt setup, hadn't even considered 144v. I keep reconfiguring what I could do in my head. The current system works great with 10kw motors at 48v, but always looking at how I could upgrade.

[kchristofferson]

Irrespective of all these arguments about efficiency, do you want to find yourself with a lee shore in heavy weather and only... how many watts do I have to get me out of trouble?

[Adelie]

Originally Posted by Dockhead

On a glassy calm, windless day?

What if you have to maneuver against a strong wind and head seas?

.....

Hmmmm. What could push a sailboat against a strong wind and head seas?

I just can’t think of anything except the Diesel engines that have be de rigueur for centuries. [emoji41]

[CaptainRivet]

You don't need diesel. If you take a 38ft cat two 10kw engines are enough, put in 2000AH of battery pack, 2KW OF Solar (LG or other high quality panels) and 2 Honda portable 2kw gennies plus a Victron Quattro 5kw. In inverter/charger. In 90% of the time the battery power should be enough, the 10% you need longer motoring you run both honda gens, which create enough power that you can do 5kn permanent for eg using the panama canal on motor.

[Adelie]

Originally Posted by noelex 77

Keep in mind that their cruising is mostly marina hopping, where shore power is frequently used to replenish the battery bank. Many people prefer this style of sailing even if there are no power restrictions, but if you prefer long term anchoring I doubt if their system would work. The energy balance does not add up.

Still, they enjoy themselves . There are no rules; adopt the style of cruising that makes you happy.

They crossed the Atlantic with a home brew electric drive, that’s not marina hopping.

In the UK and Norway they have been marina hopping but they just installed a watermaker so they could do less of that.

[valhalla360]

Originally Posted by merrydolphin

To answer the question, just follow Uma on YouTube for a while. They have been successfully cruising all electric now for a good while. They of course had a learning curve. But now have a system that seems to work well. And no, they are not sailing a super modern hi-performance boat. They have a 1970’s vintage Pierson 36 very nicely tweaked out. They have cruised a good chunk of the world and have a re-genation system so that as they sail they are recharging their batteries. As well as solar. Now granted. They don’t motor unless they have to. So if you are not an purist sailor, it may not work, but they have proven that if you like to and are able to sail a lot it works and works well. They have even eliminated propane and have all electric galley. Fascinating channel and interesting people.

Of course, they didn't prove anything. There was a time when no boats had motors.

Fact is the status quo is the ability to motor on command at 80% or better of hull speed into a significant head wind for many hours. If you drastically reduce those expectations, it's possible now.

Looping back to the title of the thread: In order for this to become the future, you will have to come up with a system that at least gets close to that capability or have some means to take choice away from those who expect that capability if you expect it to become mainstream.

Met a guy doing the ICW in a canoe with his stuff in garbage bags to keep it sort of dry. Doesn't mean that's the future of cruising simply because it can be done.

[MichaelPrichard]

Originally Posted by Na Mara

That right there is fricking genius!!!!

Seriously.

I can absolutely see exactly how I could do that as well. A neighbour in my marina has exactly the same make of boat as mine and he has a WattSea mounted on his boarding platform on one side. I would just do exactly like him but would instead have the Navy 6.0 on both sides. I could put power tilts on them and even have some way of coupling and decoupling them from the helm. With those and my bow thruster I could really make my boat dance in the marina. When in harbour or in really light winds I can lift them. When powered up I lower them for the recharge. If really crappy weather is coming I just take them off and stow them below. Hell I could even loan one for the dinghy when needed. No holes in the bottom of my boat and its cheap in comparison with alternatives.

You wouldn't want to rely on them in any kind of sloppy seas or for serious distances but then that is not the point.

TOTAL FRICKING GENIUS!!!

I am going to look very seriously into this!!

P.s. Even just as an alternative to an aft thruster this is a seriously cool idea. My wife will love it.

Funny you should mention this, and while not exactly the same, and cheating a bit since it's on a catamaran which makes this easier, I've designed and built my own retractable drives using E-Tech 7.1kW POD motors. Quick benefits (apologies if these have been mentioned already):

- fixed 3-blade props for better regen and also much cheaper
- props out of water when sailing and docked so never fouled
- easy clearing of any prop obstructions
- trivial to service without haul-out (I installed them from dinghy)

This is a 38ft. FP Athana Catamaran that weighs in at around 12,000 partially loaded. Twin Yanmar 2GM20f with saildrives removed as both were at/near end of life, leaking a lot and blowing sooty exhaust. All related holes in hull filled in for much cleaner hull.

While most comparisons of BEV boats use new batteries and compare to already installed diesels, our example flips this around some which balances out some of the cost math. It was going to cost us upward of $15k to just clean up the diesels and replace the galvanically dissolved (doh!) sail drives. What we really needed were 2 new diesels and that was probably going to push us past $20k.

We bought the E-Tech drives new and the full setup with controllers and all ancillary controls/wire come in at around $6250, or ~$13k for the pair. We powered these with 4x recycled Tesla Model S battery modules out of a wrecked car with ~40k miles on them for ~$1100 each, or $4400. This gives us 21.2kWh of juice and can push us at 5.5knots for 4 hours (5kw) or ~20 hours at 3.5knots (1kw). There are a few analyses showing that these packs are overly engineered enough to likely last over 20 years, especially given the much gentler use they'll receive on a boat vs. the car. Our BMS will "store" them at 60% charge when we're not planning any long motoring sessions further preserving lifespan.

Part of this conversion was coupled with an inverter/charger upgrade to Victron 5kw Quattro which can remotely control a (future) generator, but can also provide 10kW of burst power, supplement the 30A dock power as needed and easily powers everything including HVAC, induction stove and combo microwave/convection oven.

Regen is usable at all speeds, and while it only produces 50-100w of power at 4 knots in light winds, it can get upwards of 500-600w at 8knots, each. They're apparently capable of more like 1.2kw if properly set up which likely involves larger props, but even with our lowly 15" they're providing useful power. Our catamaran can easily support 1.2kW of solar just over the dinghy davits (we've only got 600W at the moment).

There's no doubt that I occasionally look on with envy at the boats chugging along out of our 4 mile channel at hull speed without a care in the world while I suffer a bit of range anxiety and keep our speed at 4knots to maximize the range, we've always ended the day/weekend with ample power to return. We haven't embarked on long term cruising yet, and I'm weighing the benefits of a diesel genset or even just a Honda 2.2kW portable as a way to provide peace of mind and allow for more liberal use of the full battery capacity without fears of stranding.

On our boat, the diesels were beneath the aft berths which meant ripping our bed apart to check oil, raw water strainer, sail drive oil level, belts and coolant and we endured many nights embalmed by diesel fumes. No doubt there were better mitigation strategies to solve many of these problems, but the benefit of a hybrid setup for us is the freedom to locate the genset anywhere on the boat, not shackled to the shaft or saildrive location and inducing less vibration into the boat. In the case of the portable option, we don't even have to carry it for normal daysailing or weekend outings.

One last, perhaps fanciful ideal only achievable with electric drive; straight upwind "sailing" with sufficiently large wind turbine(s). Some quick math with a pair of 2kW household sized wind turbines would allow us to go straight into the wind at 4 knots indefinitely (or at least while the wind held out). Of course there are ample issues of mounting/clearance and stowability, but at least in theory, this is possible, and for anyone that wants to sail south on the west coast of the US but also sail back without just motoring the whole way or (tacking halfway to Hawaii), this seems like a tantalizing benefit that warrants a bit of effort.

[noelex 77]

Originally Posted by Adelie

In the UK and Norway they have been marina hopping but they just installed a watermaker so they could do less of that.

Now they need to find the power for the watermaker.

It is hard to believe with only 480w of solar and cruising northern latitudes that they have any power left over to devote to propulsion. They now have some regen to supplement their solar production, but on a 36 foot boat this is going to contribute little overall power compared to amount used when motoring under electric drive and will slow them down when sailing.

Their solution, which seems sensible, is to call into marinas frequently and replenish their battery capacity with shore power. There is nothing wrong with this answer. It would be great for many couples, but not all.