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Old 10-12-2020, 08:10   #1
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The rise of electric Boats

A little inspiration for those that are looking into this . Multiple companies heading in that direction .
https://boattest.com/article/rise-el...s#main-content
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Old 10-12-2020, 09:02   #2
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Re: The rise of electric Boats

Hmmm. Diesel-electric power has some nice advantages, notably instanteous reverse by flipping a (large) switch. But for cruisers, the issue of the power source looms. Cruising boats don't return to the marina after a few hours to get a recharge.

Think about diesel direct to a propeller versus diesel to an electric motor to a propeller. You've got one extra layer of efficiency loss. It's going to take more diesel power to get the same propeller power. Solar sounds good, but it's going to take a bunch of it stored up in a Lithium ion battery bank to reliably get you to the marina, and you lose the backup that a tank of diesel fuel supplies.

Diesel-electric, like diesel-hydraulic, does have the advantage of allowing placement of the engine wherever you like. I could think that attractive to catamarans.
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Old 10-12-2020, 09:46   #3
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Re: The rise of electric Boats

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Hmmm. Diesel-electric power has some nice advantages, notably instanteous reverse by flipping a (large) switch. But for cruisers, the issue of the power source looms. Cruising boats don't return to the marina after a few hours to get a recharge.

Think about diesel direct to a propeller versus diesel to an electric motor to a propeller. You've got one extra layer of efficiency loss. It's going to take more diesel power to get the same propeller power. Solar sounds good, but it's going to take a bunch of it stored up in a Lithium ion battery bank to reliably get you to the marina, and you lose the backup that a tank of diesel fuel supplies.

Diesel-electric, like diesel-hydraulic, does have the advantage of allowing placement of the engine wherever you like. I could think that attractive to catamarans.
I like the idea of being able to have a single generator conveniently placed and quietly thumping along pretty much all the time, along with solar and maybe wind generators as well, all working together to top up some massive battery bank(s). Maybe as much as 200kWh.

I think most sailing cruisers don't actually do very many long passages where they run the engines solid for days on end. Or at least, with a little planning, wouldn't NEED to. The engines seem to get run for docking, anchoring, and a mid-day reposition round the island. Then they just sit and drink and watch the clouds go by.

As battery prices continue to fall and solar installs get more creative I totally see this being a more common option. The electric motors are coming down in price as well.

It's going to take a huge amount of battery, though. Even if it's cheap.
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Old 10-12-2020, 09:46   #4
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Re: The rise of electric Boats

If you want diesel electric then a real dual power system may be the answer for you .
https://www.sailingtoday.co.uk/pract...ectric-yachts/
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Old 10-12-2020, 13:46   #5
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Re: The rise of electric Boats

Hmmm again. There's a difference between what engine propulsion usually does and what you might need it to do, such as in a storm and you just ripped out your sails or demasted. Or, the marina is upstream on a falling tide. But, if you size the engine/generator to be able to run the props at hull speed without drawing on the batteries, then you are limited only by the size of your tank. Let solar and batteries do the job while they can, but have the engine for when they can't.

It's really the same issue as electric cars. As long as it takes longer to charge the batteries than it takes to fill a gas tank, they are at a disadvantage for anyone that wants to travel farther than one charge, and typically need a backup emgine.
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Old 10-12-2020, 14:25   #6
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Re: The rise of electric Boats

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Hmmm again. There's a difference between what engine propulsion usually does and what you might need it to do, such as in a storm and you just ripped out your sails or demasted. Or, the marina is upstream on a falling tide. But, if you size the engine/generator to be able to run the props at hull speed without drawing on the batteries, then you are limited only by the size of your tank. Let solar and batteries do the job while they can, but have the engine for when they can't.

It's really the same issue as electric cars. As long as it takes longer to charge the batteries than it takes to fill a gas tank, they are at a disadvantage for anyone that wants to travel farther than one charge, and typically need a backup emgine.
great point about "what you might need it to do"

realistically though, if you've ripped one of your sails you probably have others.
tearing the mast off...well that does seem like a doomsday situation there for a single masted boat anyway.

I've been thinking about this topic for a while now myself.
Watching Sailing Uma on youtube and their homeade electric rig seems to get them by ok with some intelligent and careful planning.

I keep thinking that having a twin engine boat with one being electric might be the ticket...or maybe better an electric main with a small petrol wing engine...but then I think that this idea might only make real sense if the petrol engine is for a generator. Now though I think that probably doesn't make as much sense as it once did.

I'd parallel the decision between hybrid EV cars and Battery EV (BEV). I used to not be overly interested in electric, but used to think that if I ever did a plug-in hybrid would be the way to go.
Plug in and go all electric for short trips but have the small generator to take you on further if ever needed. I came to realize though that this approach is a compromise... you get SOME of the advantages of an EV, but still have ALL of the disadvantages of a gasser.

Eventually, I came around to the side of BEV. I've been driving one since August. (& I'm not doing to for some sort of 'green statement'...not even close) Mine doesn't have the longest range of what's available on the market but it does me just fine... and I think your comparison of time to charge compared to time to fill up doesn't quite hit the mark. So far I'm charging at home nightly (could really go about a week without charging if necessary) and so that's wonderful...99% of my driving
but, on a road trip the time spent actually charging is longer than filling up, true... but the total time spent at the station isn't much different than what I'd spend at a gas station once you figure restroom break, buying some food, etc... so it's almost a wash...and getting better all the time with better charging networks and longer range cars...

Seems to me the key to EV boats is to have multiple charging methods available.
and perhaps redundant systems.... twin motors with isolated battery banks.
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Old 11-12-2020, 02:46   #7
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Re: The rise of electric Boats

Have a read of this article.
Even with the experts it is very difficult, and expensive, to get something to replace diesel engines / generators.
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Old 11-12-2020, 02:58   #8
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The rise of electric Boats

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Originally Posted by tkeithlu View Post
......

It's really the same issue as electric cars. As long as it takes longer to charge the batteries than it takes to fill a gas tank, they are at a disadvantage for anyone that wants to travel farther than one charge, and typically need a backup emgine.


All cars are compromises.Evs have a current disadvantage that refilling them with “ fuel” takes more time

Against that, they are typically cheaper to run insure , tax , accelerate faster , quieter , nicer to drive , need less to no servicing , and doesn’t use a monopolistic supply chain fuel source

It’s all about the balance of compromises.

And EVs don’t “ need “ a backup engine mine does 450km and at that I fall off the island before that figure is reached
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Old 11-12-2020, 03:19   #9
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Re: The rise of electric Boats

I had a good look at this stuff for my cat. Cats are uniquely suited to diesel electric. Also gobs of extra electricity makes for wonderful conveniences in livability and a good way to get rid of a lot of marine stuff.

My conclusion?

If you want to turn a cat into a dog, this is how you do it. The weight is ridiculous.
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Old 11-12-2020, 03:53   #10
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Re: The rise of electric Boats

How much would a full carbon catamaran save in weight? 40%?

So if you built a lagoon 560 out of carbon then you have 12 tons of battery to play with. That's 43 BMW i3 batteries at 40kwh each for a total of 1726kwh.

On the other end you have a Two oceans 60 Carbon weighing 10 tons, so probably a decent amount of payload as well but a lot easier driven hull.

Answer is how do we make the boats lighter.

Here is a carbon nanotube/graphene prepreg boat. 54 foot weighing 8400lb or 3.9 tons. You probably need the batteries as ballast even in a cat. Still no way to generate that much power underway but you can probably charge her up and she would be able to cross the atlantic.

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Old 11-12-2020, 04:04   #11
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Re: The rise of electric Boats

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How much would a full carbon catamaran save in weight? 40%?

So if you built a lagoon 560 out of carbon then you have 12 tons of battery to play with. That's 43 BMW i3 batteries at 40kwh each for a total of 1726kwh.

On the other end you have a Two oceans 60 Carbon weighing 10 tons, so probably a decent amount of payload as well but a lot easier driven hull.

Answer is how do we make the boats lighter.

Here is a carbon nanotube/graphene prepreg boat. 54 foot weighing 8400lb or 3.9 tons. You probably need the batteries as ballast even in a cat.

This is a completely backwards way to look at it.

“Let me build the most advanced, lightweight boat imaginable. Now let me find ways to make it into a Lagoon.”

Carbon is not the be all, end all in weight reduction. Properly engineered glass boats can be built just as light or lighter if the design principle is adhered to throughout the process. Every pound/kg counts is the way to a high performance boat. For instance, my glass boat weighs significantly less than a carbon gunboat of the same dimensions. Hopefully I’ll be able to keep it that way. Although a few sacrifices for comfort have been made.

Having all the extra batteries, heavy wiring, heavy electrical control devices, plus a Diesel engine big enough to run the boat, plus a tank full of diesel, plus big props, plus starting batteries makes for a dog of a cat.
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Old 11-12-2020, 04:08   #12
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Re: The rise of electric Boats

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.
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Old 11-12-2020, 07:20   #13
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Re: The rise of electric Boats

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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.
Actually the biggest concern here is power generation to run the electric propulsion.
There aren't to many places to stop off and recharge between Avalon and Pape'ete.
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Old 11-12-2020, 07:32   #14
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Re: The rise of electric Boats

We are seriously hoping the new FP51 will introduce the new Volvo electric drives, should know next week.

What I’m thinking is that this comes down to hull length. Displacement hulls and power needed is efficient and longer/larger cat’s can take the weight of the batteries, have the area needed for the solar, can carry the generator needed to run the drives when battery capacity runs out and make this all work without a significant sacrifice.

I think this is not the answer for a 40 ft cat but if you look at the new eco Sunreef’s and how much solar they can put on it, it starts to make sense.

Again this seems to not be the solution for everyone.

As for the weight, keep in mind the electric motor weights a lot less than the Diesel engine and can be made for the prop speed thereby potentially eliminating a gear set. Water cooling and reuse of the heat makes them thermally efficient for a period of time.

Finally torque equals acceleration and horse power is speed. Speed is NOT a factor for displacement hulls so the increase in torque for electric over diesel means you need a smaller primary mover.

This is all about compromise. If you want to motor across an ocean don’t go electric. If you can live with the compromise then it’s an attractive solution.

Imagine not having to source “bad diesel” in remote islands around the world and your only down side is you can’t motor forever.

Like everything, good for some, not for others. Think about the charter market where they rarely sail, rarely move far and the elimination of maintenance and fuel costs. That market alone will drive this forward.
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Old 11-12-2020, 07:58   #15
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Re: The rise of electric Boats

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Actually the biggest concern here is power generation to run the electric propulsion.
There aren't to many places to stop off and recharge between Avalon and Pape'ete.
It is with the current cost of lithium and weight. But if we assume for a minute 2000kwh of lithium battery can be fitted into a large lagoon type boat. That would give it a range of about 2000 nautical miles according to ocean volt numbers, a steady 5 knots, lets half that to 1000NM, it's still decent. https://oceanvolt.com/twin-shaftdrive-20/

The way to get there would be using something like the new tesla batteries with an energy density of 350wh/kilo (current lifepo4 is about 100wh/kilo). This would make the battery pack about 7 tons assuming about a 20% increase in weight from packaging.

If you made a lagoon 560 from carbon it would save you 12 tons so it is possible.

Overall, I think with a light hull and denser cheaper batteries we can still have cruising when diesel is eventually gone. New IC cars will be banned by 2030/2035 so its not that far off. I'll be around when diesel is no longer an option.
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