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Going electric?


Marfal
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Hi everyone, 

 

I am dreaming of one day building a boat. The Ocracoke 20 and Marissa are beautiful designs and are right now the favourites. 

 

However, since I am in the dreaming stage and will remain here for at least some time I can't help but think about future rigging options that will be available to me once I actually get to building. 

 

I live in Europe where the green movement is strong and there is strong support for electric propulsion. And if these trends persist I am not going to have much of an option, I will have to go electric. 

 

A key feature of electric boats is fuel economy, which I think works really well with the ocracoke and marissa designs as they are very economic. But how much battery weight can for example a Marissa manage before having to make major modifications? Does putting 150kgs of batteries under the console ruin the design? How about 300kgs?

 

I am assuming it will be powered by a 40-60 hp equivalent outboard. 

 

Batteries are constantly getting lighter and more powerful (and thankfully cheaper as well) . To me it would be interesting to try to understand when my requirements for weight, range, and price will be met. 

 

So what do you guys think? Are these design suitable for electric propulsion? 

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Small electrics are already practical, though pricey compared to petrol. The larger ones are starting to catch on, but they don't seem to have a great range/run time and are very expensive. Technology in DC electric and storage of it are moving fast. It may well come down in price over the next few years.

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Hi Marfal,

 

We get asked this question a lot. We have been following EP for a long time and we have seen some real improvements especially for slow speed displacement boats. There are some planing hulls that have gone electric which is exciting but at this point in the evolution it is still hard to compete with the amount energy that a liter of petrol has stored.

 

To get a boat to plane, it is all about power to weight. Yes you can go fast for a short time and if you have somewhere to recharge you are good to go again but that is not often available or convenient. If you want range then the weight of batteries and Euros starts really going up.

 

To answer your question, 150 kgs of batteries under the console would be no problem on the Marissa. Even 300 kg is acceptable. Some of that weight would be offset by leaving out the fuel and tank. Also electric motors are usually lighter than outboards so it would be like having to carry an extra couple of people on board. As to 300 kgs of batteries fitting exactly under the console, there would probably have to be some redesign as we do not know their dimensions.

 

Perhaps when it is time for you to stop dreaming and make it a reality, the cost of a KW of battery energy will compete with a KW of petrol but as Dave was suggesting, we are not there yet. With the high cost of petrol in Europe you will probably get there before us.

 

 

 

 

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Hmm, well, Torqeedo's Deep Blue 25 outboard is about 305 lbs vs. a Yamaha 40 hp 4 stroke at 215 hp, so the motor is a bit heavier. Not a surprise.  I've been working w/ high speed aerospace brushless PMAC motors in the same power range for a while, and they are pretty dense, if compact.  There's quite a bit of copper and magnet mass there.  It looks like Torqeedo is configuring full systems using a BMW i3 battery pack (at 360V it's not a DIY install) weighing a bit over 600 lbs.  That's equivalent to 97 gallons of gasoline (not counting the tanks, etc.) in weight, but not in total energy.  Figure tanks, etc for gas would be 100 lbs so that'd be 79 gallons of gas.  I do like that they are going to an existing, production battery system so fewer surprises and probably more reliable price structure.  And the system is targeted at planing boats as well as displacement.

torqeedo-deep-blue-40-rl-measurements.pd

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On 9/9/2021 at 10:00 PM, Hirilonde said:

Small electrics are already practical, though pricey compared to petrol. The larger ones are starting to catch on, but they don't seem to have a great range/run time and are very expensive. Technology in DC electric and storage of it are moving fast. It may well come down in price over the next few years.

Technology is indeed moving fast. However I fear that demand will keep prices high for at least a few years. But like with computers etc, prices will come down and performance will keep improving. 

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On 9/10/2021 at 2:08 AM, Designer said:

Hi Marfal,

 

We get asked this question a lot. We have been following EP for a long time and we have seen some real improvements especially for slow speed displacement boats. There are some planing hulls that have gone electric which is exciting but at this point in the evolution it is still hard to compete with the amount energy that a liter of petrol has stored.

 

To get a boat to plane, it is all about power to weight. Yes you can go fast for a short time and if you have somewhere to recharge you are good to go again but that is not often available or convenient. If you want range then the weight of batteries and Euros starts really going up.

 

To answer your question, 150 kgs of batteries under the console would be no problem on the Marissa. Even 300 kg is acceptable. Some of that weight would be offset by leaving out the fuel and tank. Also electric motors are usually lighter than outboards so it would be like having to carry an extra couple of people on board. As to 300 kgs of batteries fitting exactly under the console, there would probably have to be some redesign as we do not know their dimensions.

 

Perhaps when it is time for you to stop dreaming and make it a reality, the cost of a KW of battery energy will compete with a KW of petrol but as Dave was suggesting, we are not there yet. With the high cost of petrol in Europe you will probably get there before us.

 

 

 

 

I agree that today EP does not compete with ICEs. But as technology and regulation progresses I believe it will catch on. 

 

I can manage a shorter range since I typically never use even half of the available fuel today. But it is always nice to have the range if my situation would change. 

 

Unfortunately most electric outboards seem to weigh close to their petrol counterparts, and costs more! Proponents of EP always say that it's superior from a service perspective with only 3 moving parts.. Well, that should translate to less manufacturing cost. Higher efficiency should also translate to lower weight. I'm a bit disappointed with EP in this regard. 

 

Good to hear that it is feasible to make an EP version of marissa. Then I can keep daydreaming. Or as I like to call it, mentally prepare. 

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21 hours ago, BradW said:

Hmm, well, Torqeedo's Deep Blue 25 outboard is about 305 lbs vs. a Yamaha 40 hp 4 stroke at 215 hp, so the motor is a bit heavier. Not a surprise.  I've been working w/ high speed aerospace brushless PMAC motors in the same power range for a while, and they are pretty dense, if compact.  There's quite a bit of copper and magnet mass there.  It looks like Torqeedo is configuring full systems using a BMW i3 battery pack (at 360V it's not a DIY install) weighing a bit over 600 lbs.  That's equivalent to 97 gallons of gasoline (not counting the tanks, etc.) in weight, but not in total energy.  Figure tanks, etc for gas would be 100 lbs so that'd be 79 gallons of gas.  I do like that they are going to an existing, production battery system so fewer surprises and probably more reliable price structure.  And the system is targeted at planing boats as well as displacement.

torqeedo-deep-blue-40-rl-measurements.pd

Yeah, torqeedo does not make sense to me. Also looking at their range charts it shows very short range at speed. I believe they are using bigger boats in their calculations as other calculations I have seen are more favourable. 

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