The rise of electric Boats

[capn_billl]

For most sailboats, you only use the props for short periods.

The electric motor I used has regeneration.

The low current (10% PI) causes very little drag.

Under normal operation regeneration plus solar could easily keep a battery bank topped off.

Electric drive has been the norm for Transoceanic freighters for over 50 years.

Price, and battery technology has brought this to smaller boats.

[Adelie]

Originally Posted by capn_billl

....

Electric drive has been the norm for Transoceanic freighters for over 50 years.

....

Not so. Marine Diesel-electric drive is only regularly used for specific uses:
Ferries that need quick response to helm commands.
Cruise ships that lately have tended to use electric azipods plus bow thrusters to make quicker docking without tugs at out of the way ports of call.
Ice breakers that need quick and repeated reversals of thrust, high thrust at low speed and high reliability.

Most large freighters use direct drive from the diesel. That is that in cases where they need reverse the engine is stopped and restarted running backward. There is no clutch.

Why direct drive? Efficiency and cost, both initial and maintenance.

There are plenty of smaller freighters with clutches and transmission or diesel-electric drive that are intended to serve smaller ports or places with limited tug services.

[Chotu]

Originally Posted by Yihang

Well. Your boat built out of carbon would be even lighter.

The lagoon example is just the extreme. looks like that is what silent yacht approach is.

We are not talking about sailing per se here. But balancing weight and load carrying is the way to make electric propulsion possible in the long run.

The issue is always weight of batteries is it not. Since it doesn't look like we will have a miracle battery anytime soon reducing weight in other areas is the way forward.

again, sailing performance is not the point here.

It’s in the sailing multihull section so aren’t we talking about sailboats?

My boat built of carbon then fitted out wrong would weigh way more than it does.

That’s my point. The weight is added after the hull is made. The hull isn’t that big of a deal actually. My hull weighs about 10,000-12,000 lbs. Boat has a 20,000 lbs max displacement. The less of that displacement I use, the better the boat.

Carbon isn’t a be all end all.

But dumping in all those 0/0/0/0/0 cables, massive controllers, huge Diesel engine, pair of electric motors, more batteries, etc etc will ruin any boat.

And yes, this is the sailing multihull section.

[BigBeakie]

Comparable sized electric motors with their controllers are about half the weight of a marine diesel. So what you save in engine weight, you add back in propulsion lithium bank. So it's a wash. The extra weight of cabling is more than made up for by savings in weight of diesel fuel to feed 2 diesel engines. The DC genset diesel can be smaller/lighter than the propulsion diesel that was replaced by the electric motors.

There should be a net savings in weight for an EP cat if the systems designed was done correctly.

However, there needs to be a careful analysis of what the power requirements are for the use case of the boat. If extended motoring in adverse conditions is expected ( ie beyond the planned propulsion battery bank capacity ) then the DC genset needs to be sized accordingly.

You will need the hull resistance data to do this analysis of what the EP specifications should be. And be sure to add in the wind resistance data as well, as this will be an important consideration, depending on where you cruise.

[Rennsail]

I've been observing this evolution from the sidelines. Don't really have a strong opinion on electric vs diesel vs hybrid. However, I did find this update interesting. S/Y "Top Secret" is/was a bit of an internet celebrity several years back as its owners had installed 4 Oceanvolt SD15 motors (she is a 58' Voyage catamaran). Apparently she took a lightning strike in 2019 while on the hook (I think) in Savannah. The electronics were severely damaged and the owners soon realized they no longer had any form of auxiliary propulsion. Subsequently they pulled two of the four SD15's and installed 2 55hp Volvo diesels in their place. This 2 electric / 2 diesel configuration seems to be working well for them now.


https://integrelsolutions.com/blog/2...580-catamaran/


EDIT: This boat is apparently for sale: https://www.yachtworld.com/boats/200...e-580-3736488/

[Chotu]

Originally Posted by BigBeakie

Comparable sized electric motors with their controllers are about half the weight of a marine diesel. So what you save in engine weight, you add back in propulsion lithium bank. So it's a wash. The extra weight of cabling is more than made up for by savings in weight of diesel fuel to feed 2 diesel engines. The DC genset diesel can be smaller/lighter than the propulsion diesel that was replaced by the electric motors.

There should be a net savings in weight for an EP cat if the systems designed was done correctly.

However, there needs to be a careful analysis of what the power requirements are for the use case of the boat. If extended motoring in adverse conditions is expected ( ie beyond the planned propulsion battery bank capacity ) then the DC genset needs to be sized accordingly.

You will need the hull resistance data to do this analysis of what the EP specifications should be. And be sure to add in the wind resistance data as well, as this will be an important consideration, depending on where you cruise.

Absolutely

My response is through the lens of cruising, which assumes anchoring our, motoring for days on end occasionally, few if any docks, etc.

In other words: you’d need that monster diesel generator that weighs as much as the propulsion system in a standard ICE boat.

If cruising, there’s no free lunch. You need the full diesel power and the diesel to burn to run it. If you’re going day sailing or for the weekend, electric makes perfect sense. So long as your utility costs are reasonable at the dock.

[newhaul]

Here is a bit of where reality meets fantasy
Electric Shock by Jimmy Cornell | Nautic Magazine
Its just not there yet.

[Rennsail]

Originally Posted by newhaul

Here is a bit of where reality meets fantasy
Electric Shock by Jimmy Cornell | Nautic Magazine
Its just not there yet.

Well, it was a noble effort. This quote form the article seems to summarize the current state of the evolution:


"An electrical engineer by profession, he was the best person to comment on my predicament. His verdict was unequivocal: “Jimmy, your concept may be right but it is premature. There is no way an electric sailing vessel of any size could regenerate sufficient electricity to keep the battery bank, however large, in balance and cover all consumption at the same time. This is why I decided on a hybrid solution. And by the way, after 18 months and an Atlantic crossing, my own regeneration system, based on an electric motor with shaft drive and folding propeller, is still not working to my satisfaction. In fact, it doesn’t work at all.”"

[Pete7]

Sounds like wild camping on a brand new 45ft cat

"we did not boil water, had no hot drinks"

[capn_billl]

Originally Posted by Adelie

Not so. Marine Diesel-electric drive is only regularly used for specific uses:
Ferries that need quick response to helm commands.
Cruise ships that lately have tended to use electric azipods plus bow thrusters to make quicker docking without tugs at out of the way ports of call.
Ice breakers that need quick and repeated reversals of thrust, high thrust at low speed and high reliability.

Most large freighters use direct drive from the diesel. That is that in cases where they need reverse the engine is stopped and restarted running backward. There is no clutch.

Why direct drive? Efficiency and cost, both initial and maintenance.

There are plenty of smaller freighters with clutches and transmission or diesel-electric drive that are intended to serve smaller ports or places with limited tug services.

The Bulkgear boats, and several lines of container ships, and tankers I worked on had electric drive with superconductor motors, and cryo systems.

I did the automation controls for the system.

They had two 12mw turbo diesel generators on the aft deck to charge the battery banks, and produce auxiliary power.

[Seaslug Caravan]

Originally Posted by BigBeakie

Comparable sized electric motors with their controllers are about half the weight of a marine diesel. .

Once again you miss out the important facts.

Add the weight of a diesel plus attached generator, which you state is necessary, plus cabling plus fuel plus fuel tanks etc etc and blind Freedy can see you are being misleading.

The crux of the failure lies here...... " On average we found that the two propellers could only produce an hourly net charge of 0.6% of the total battery capacity, equivalent to 336 Watts."

good luck if you own a mono with one motor.

from... Electric Shock by Jimmy Cornell | Nautic Magazine

Thats right, the average speeds/conditions in the real world for that passage would only allow an average of 168 watts per hour per motor.

Thank goodness they didnt run into bad weather or lose the rig where extended / full power motoring was required.

[Yihang]

Originally Posted by Chotu

It’s in the sailing multihull section so aren’t we talking about sailboats?

My boat built of carbon then fitted out wrong would weigh way more than it does.

That’s my point. The weight is added after the hull is made. The hull isn’t that big of a deal actually. My hull weighs about 10,000-12,000 lbs. Boat has a 20,000 lbs max displacement. The less of that displacement I use, the better the boat.

Carbon isn’t a be all end all.

But dumping in all those 0/0/0/0/0 cables, massive controllers, huge Diesel engine, pair of electric motors, more batteries, etc etc will ruin any boat.

And yes, this is the sailing multihull section.

Ok, i'll stop mentioning carbon, seems to be a trigger for you. Let's just say a lightweight composite...

All the furniture would have to be foam cored and built into the structure as well of course. Condomarans can reduce weight easily with this and composite bulkheads, right now they are still using plywood.

The thread is about electric boats, not sailing per se. Unfortunately we don't have an electric boat section. We will eventually run out diesel so the discussion is about pure electric. I don't know why you keep bringing a heavy generator into the discussion.

All I'm saying is when diesel is no longer an option sometime around 2030(no more new IC cars allowed) we will need boats that are lighter to accommodate more batteries so people who like heavy condomarans can still motor a decent distance, this can be done easily with foam cored bulkheads and furniture in condomarans. People like us who like lightweight perf multis can benefit from the denser battery technology, although it would be harder for us to get significantly more battery capacity because performance hulls are already as light as they can be, without going carbon nanotube/Graphene (sorry ).

For the charter market this will be an easy transition. Just add more batteries and take out the weight from somewhere else. For the long distance cruiser market or perf cat market we will need to be more creative in reducing weight.

For sure without diesel the older heavy mono hulls will be in trouble.


PS OCTenders can reduce the weight in their tenders by 20% purely from going to pure carbon so the weight savings is not insignificant. We will need everything we can get for batteries. Again we are talking abut pure electric here.

[Yihang]

https://www.carsguide.com.au/car-new...ext-year-81254

Take it for what it is but Volvo is ending diesel engine production next year in it's cars.

[newhaul]

Originally Posted by Yihang

https://www.carsguide.com.au/car-new...ext-year-81254

Take it for what it is but Volvo is ending diesel engine production next year in it's cars.

You keep missing the fact that marine is not terrestrial. They will never ( in my lifetime) get rid of diesel fuels.

[Yihang]

Originally Posted by newhaul

You keep missing the fact that marine is not terrestrial. They will never ( in my lifetime) get rid of diesel fuels.

Yes, that's why I said take it for what it is.

For sure diesel will be available for industrial use for some time to come but I wonder about it's availability to recreational boating. After all, the charter market and marina set can probably get by with electric that leaves the cruisers, which make up a niche within a niche market.

In 10 years when I'm in the market I don't think a new diesel engine would be wise or even available if the ban on new IC engines extends to recreational boating.

Things are moving fast. I think we can all agree governments don't give a crap about recreational boaters and certainly not cruisers.