Viability of electric only propulsion in 2018 - is there a good option after all?

[CaptainIglo]

This https://youtu.be/-uTy5owBsUE is a pretty good analysis of what it would mean to dispense with Diesel engines and go fully electric for propulsion.

The tldr is electric range 20nm with 4 Tesla power walls (which aren’t marine certified but are used for thought experiments sake) versus 800nm with the 700 liter diesel tank of the leopard 45. (Its 800nm at 5 knots or 400nm at close to 8 knots, more on that later)

OUCH!

Double ouch because 4 Tesla power walls provide enough power to supply 3 single family homes with enough power for 24 hours.

That really is a shame, it seems to me that not only is electric a more elegant solution (more quiet, no smelly exhaust) but has so many benefits. Feel free to correct me if I’m wrong or missing something

- maintenance on a electric drive train is less complicated because they are mechanically much simpler, engines last longer
- engines like the oceanvolt servoprop can double as hydrogenerators when not in use without clumsy mechanisms to lower them into the water (I’m looking at you watt&more)
- having a large battery bank for engines provides a big comfort bonus and gives you a lifestyle close to onshore living

But... Is there another option that would give a similar range than Diesel engines?

I did some quick napkin math.

The above mentioned oceanvolt Servoprop has a 15kw engine. According to some online resources a 20kw generator (so we have some spare capacity) uses about 1.6 gallons/ 6.4 liters per hour at full load. That means you could run it for about 109 hours on above mentioned 700 liter tank.

Ocean volt specs say the max Speed of a servo prop on a 45 foot multihull is about 8.5 knots.

Let’s assume 8 knots sustained is realistic. This would give you a range of 872 nm - which is not only a superior range to diesel but at almost twice the speed on top of it. And the 872nm are not the hard limit of the range but only what you could do in “one go”. You would still be able to do 20nm indefinitely per recharge cycle if you have wind to hydro generate or solar.

So is hybrid the way to go? Even if running a single generator still means relying on diesel, it is easier, quieter, requires less maintenance than running 2 large Diesel engines

Certainly, the initial purchasing cost is higher but you would likely find the 20nm range provided by hydro generated power sufficient in most cases for things like getting back to the Marina or get into the wind so this would amortize against reduced diesel cost.

Am I missing something?

Shouldn’t this be the holy grail of sailing propulsion?