Sail boat engine choice - electric or diesel

[newhaul]

Originally Posted by Booysen

I believe they Uma have recently abandoned the Electric Motor and are returning to the more reliable Diesel! Check for yourself don’t believe me !

Nope they converted saildrives to electric

[Adelie]

About a year ago the Uma folks gave up their DIY electric drive for a used commercially available electric sail drive which more recently had some serious problems which the manufacturer repaired, probably because they are so high profile.

[Adelie]

Originally Posted by MichaelPrichard

This scenario is just as valid if inverted; IC engine cars make amazing long distance cruisers, but bring them into a city and they "no longer stack up". Electric cars are far superior with zero warm up time, fully charged in the morning, no trips to gas stations, no excessive engine wear due to frequent short trips that fail to heat the block up causing pre-mature carbonizing/wear/pollution, silent running, pre-warmed in winter/pre-cooled in summer, etc (the list is very long). Average commute in the US is 16 miles, but even extreme commutes are usually less than 200 miles round trip per day, well within the range of most electrics offered today. With much lower operating costs, you can easily afford to rent a long range IC car the half dozen times a year you might take a long trip. It's a difficult scenario for many of us (myself included) to break through the range anxiety that comes from the known long distance limitations of electrics, but every one of the dozens of friends of mine that have gone electric wonder why they didn't do it sooner and none has expressed any frustrations or regrets, and none have (thus far) switched back to an IC car.



I find hydrogen fuel cell cars a fascinating direction and hope for some expansion there, but they're fundamentally just electric cars with a fuel cell strapped on to provide a more "gas like" fueling experience which I see as a short term bridge to pure electric since the ability to "fuel up" at home with a large EV battery is really one of the ultimate conveniences. With the rapidly advancing battery tech already out there, I fear it's market window may be closing, but perhaps some form of chemical storage -> fuel cell -> electric propulsion will emerge that will allow full IC replacement for those that need regular long distance travel.



These technologies needn't be either/or; the greater variety there is, the better the optimization for each user's needs, ideally while lowering natural resource use and pollution. With 80% of driver's actual needs (probably higher) now met by pure EVs, we just need a wider array of them to expand their appeal beyond the technical.



Apologies for the thread digression, but this same basic principle is at play in the electric vs. diesel debate; many sailors needs can now be met by electric propulsion. There is hardly a market for it yet and the boat market is so much smaller with much slower turnover, but many of us enjoy the bleeding edge, especially as it turns into the new normal. I don't know how long this will take, but I don't think 20 years will be required to convert much of the new sailboat fleet into some form of electric propulsion. And I'm especially intrigued by the possibilities of an equally quick push toward large props as a really big efficiency advance as this does feel like thoroughly under-explored territory.

I saw a very good analysis of why hydrogen fuel cells would be a bad bet on taking over the car market. Big issues include:
1. Low energy density, needs a very large tank to have a reasonable range.
2. Weight penalties due to needing to store the hydrogen onboard as a compressed gas rather than as a liquid.
3. Various safety issues.
4. High cost of creating a new distribution network
5. High cost of generating hydrogen gas without using fossil fuels to do it.

As an example of issues 1-3 consider the use of CNG for cooking aboard instead of propane.

The reasons it won’t likely work for cars apply to boats too.


The energy density as specific energy of liquid fuels is very compelling and at some point I would expect someone to start making synthetic fuels using wind or solar as the primary energy source. Most of the existing engines will work on synth fuels and there is an existing distribution network.

[Q Xopa]

Originally Posted by Shaneesprit

I am sorry but all boat owners are evil by the logic in this forum, except those that sail on bamboo using cotton sails,
The rest of use have a huge chunk of floating plastic with, batteries- made of plastic and Acid with precious metals dug out of mines with huge environmental impact.
Don’t claim that you have batteries so you are superior to a Diesel engine owner, that’s just the thought of the decade, pretty soon your going to be the evil one when the battery disposal scandal starts in 10 years.
So far in my 46 years, I struggle to think of a single change for environmental reasons that didn’t back fire!
Any thoughts of ones that didn’t?
I have a long list that really did

Cotton sails environmental, pfaaaa. Maybe you havent heard of the environmental impact growing cotton has. Huge water usage, moth killing poison sprayed every few days etc

[Cloroxbottle]

Originally Posted by carstendenmark

I have a 44 year old inboard Volvo MD6A (10 HP) in my 29' Maxi 87 GRP sailboat. I bought the boat two years ago.

It starts every time, but it is tired (max is 1600RPM, rated 2200) and underpowered for the waters that I am sailing.

I am considering an upgrade to a 18KW electric watercooled motor (Thunderstruck or similar) for the benefits of low maintenance, low overall noise level and sufficient power in rough conditions.
And the best : No more diesel fumes below, no more oil spills, no more oil and filter changes !!!

Like you, I have a tired older Volvo Penta diesel. Not as old as yours, but 20 years. I just replaced the fuel line along with the filters and pumped contaminated diesel out of the tank and took it for recycling. VP wanted $250 for the fuel line with fittings... So I got to work on the cracked line with a dremel cutting tool, pulled the fittings, installed them in standard west marine fuel line with two stainless hose clamps and fabricated a serviceable replacement for $40.

I actually emailed Oceanvolt because I would like nothing more than to replace the engine, tank, filters, Jerry cans, spare belts, spare hoses, oil, coolant, biocide and all of it with an electric engine.

I can motor 175 miles on a full diesel tank... And I am prepared to sacrifice some of that range to make the switch. But I'm not prepared to go from a 175 mile range to a 30 mile range to do it.

Maybe someday (my personal cutoff is to be able to cross the Gulf stream from Miami to Bimini under engine power, just so you know).

[s/v Jedi]

For those demanding at least so many hours of motoring at hull speed before considering an electric motor to replace diesel: why hull speed? why not accept a lower speed or assist from a genset? Even if you would motor a lot and require running the genset regularly, it would still save a huge amount of fuel.

Our hull speed is 12 knots and when motoring, I accept 6 knots which is attained at only 1,500 rpm with the diesel.

Also, I see people write: why would I run a diesel genset to make electricity to charge batteries to run an electric motor when the diesel can turn the prop directly?! This is a flawed statement. First of all, you’re supposed to charge the batteries using shore power or better yet, solar panels. Second, when running a genset for sustained electric propulsion, you are not charging batteries: the generated power goes from genset straight into the electric drive, skipping the battery charge/discharge losses.

[Cloroxbottle]

Originally Posted by s/v Jedi

For those demanding at least so many hours of motoring at hull speed before considering an electric motor to replace diesel: why hull speed? why not accept a lower speed

Weather windows. Distances to motor from a berth to your sailing grounds. If you have a four mile motor from your slip to open water, accomplishing that at 2 knots vs 4 or 5 doubles the amount of time it takes to get in or out. Motoring into a 2 knot current at 75% of hull speed only yields 3 knots.

Or assist from a genset? Even if you would motor a lot and require running the genset regularly, it would still save a huge amount of fuel.

Our hull speed is 12 knots and when motoring, I accept 6 knots which is attained at only 1,500 rpm with the diesel.

Also, I see people write: why would I run a diesel genset to make electricity to charge batteries to run an electric motor when the diesel can turn the prop directly?! This is a flawed statement. First of all, you’re supposed to charge the batteries using shore power or better yet, solar panels. Second, when running a genset for sustained electric propulsion, you are not charging batteries: the generated power goes from genset straight into the electric drive, skipping the battery charge/discharge losses.

Replacing an inboard diesel with a genset + large battery bank + electric motor requires more room, increases systems complexity, and basically eliminates the advantages of having an all electric boat.

[Q Xopa]

Originally Posted by mcarthur

Ooo - can you say where you got those images? I'm interested if they have a clutch in there for the electric or not. The cost for such a clutch seems high from the quotes I've had, so I was intending just to run it without (yes, the gearbox model can freewheel!).

I used a Superiordriveline.com driveshaft disconnect. I dont know how much expensive is but I paid $790.

[MichaelPrichard]

Originally Posted by Cloroxbottle

Weather windows. Distances to motor from a berth to your sailing grounds. If you have a four mile motor from your slip to open water, accomplishing that at 2 knots vs 4 or 5 doubles the amount of time it takes to get in or out. Motoring into a 2 knot current at 75% of hull speed only yields 3 knots.

This scenario, however, does imply a day sail which would allow one to consume more power electrically at the expense of total range. For instance, we have around 40 miles of range at 4 knots, but if we're only going to day sail, we'll happily consume at our "20 mile" rate of 5.5-6knots to get there quicker; our channel is 3.5 miles, so that leaves ample margin.

Originally Posted by Cloroxbottle

Replacing an inboard diesel with a genset + large battery bank + electric motor requires more room, increases systems complexity, and basically eliminates the advantages of having an all electric boat.

Not necessarily; as per my example above, one would typically only need a genset of 50% the wattage of the diesel-only engine as long as the batteries could provide the difference for hull speed travel for the required distances (either emergency or just convenience). You'd still have all the other advantages of electric-only operation without sacrificing range, just long distance hull-speed travel, which in a sail boat will usually be accomplished by the sails anyway. If long distance cruising under power is common for you, upping the size of the generator is still an option while retaining the electric advantages and allowing for placement of the generator anywhere in the boat.

I'm not quite sure how your 3 component electric setup "eliminates the advantages of having an all electric boat"; we have no propane, a much nicer induction stove, can run the AC all night (with no generator), enjoy silent motoring in/out of our marina, to mention a few of the advantages retained even if we added that generator (which we haven't yet).

[newhaul]

Originally Posted by MichaelPrichard

This scenario, however, does imply a day sail which would allow one to consume more power electrically at the expense of total range. For instance, we have around 40 miles of range at 4 knots, but if we're only going to day sail, we'll happily consume at our "20 mile" rate of 5.5-6knots to get there quicker; our channel is 3.5 miles, so that leaves ample margin.



Not necessarily; as per my example above, one would typically only need a genset of 50% the wattage of the diesel-only engine as long as the batteries could provide the difference for hull speed travel for the required distances (either emergency or just convenience). You'd still have all the other advantages of electric-only operation without sacrificing range, just long distance hull-speed travel, which in a sail boat will usually be accomplished by the sails anyway. If long distance cruising under power is common for you, upping the size of the generator is still an option while retaining the electric advantages and allowing for placement of the generator anywhere in the boat.

I'm not quite sure how your 3 component electric setup "eliminates the advantages of having an all electric boat"; we have no propane, a much nicer induction stove, can run the AC all night (with no generator), enjoy silent motoring in/out of our marina, to mention a few of the advantages retained even if we added that generator (which we haven't yet).

If you can do all that without a generator what size is your lfp house bank? What was the cost of said bank to do all that?

[MichaelPrichard]

Originally Posted by newhaul

If you can do all that without a generator what size is your lfp house bank?

We've got 21.2 kWhrs of Li-Ion. Running the AC all night would likely consume 50-80%, so not really a "good" idea in most scenarios, just showing that it's a possibility. I feel that many general criticisms of electric propulsion don't account for the potential solutions in specific instances. With enough solar, we would potentially risk more frequent use of AC in anchorages, just haven't sailed to those destinations where that's required yet. We're still working out the best modes for our system, but I anticipate having a generator before we take any long cruises. Working out the size of the generator is the only question.

[newhaul]

Originally Posted by MichaelPrichard

We've got 21.2 kWhrs of Li-Ion. Running the AC all night would likely consume 50-80%, so not really a "good" idea in most scenarios, just showing that it's a possibility. I feel that many general criticisms of electric propulsion don't account for the potential solutions in specific instances. With enough solar, we would potentially risk more frequent use of AC in anchorages, just haven't sailed to those destinations where that's required yet. We're still working out the best modes for our system, but I anticipate having a generator before we take any long cruises. Working out the size of the generator is the only question.

So about 1600ah ( at 13.5 vdc )
How big is your battery charging capability? That's what you should gauge your genset on .
The charging ability should be about 75% of the capacity of the genset

[s/v Jedi]

Originally Posted by newhaul

So about 1600ah ( at 13.5 vdc )
How big is your battery charging capability? That's what you should gauge your genset on .
The charging ability should be about 75% of the capacity of the genset

When you charge LiFePO4 I think you want to do that at 0.5C so that is about 10kW in this case. That would be close to 400A for an 8S battery or 800A for a 4S battery.

I’m working on a 10kWh bank with about 3.5kW charging capacity from the inverter-chargers plus almost 2kW from solar.

[newhaul]

Originally Posted by s/v Jedi

When you charge LiFePO4 I think you want to do that at 0.5C so that is about 10kW in this case. That would be close to 400A for an 8S battery or 800A for a 4S battery.

I’m working on a 10kWh bank with about 3.5kW charging capacity from the inverter-chargers plus almost 2kW from solar.

That is correct for maximum life it is not recommend to charge at above a .5C. However it is very rare for a small boat to have that kind of charging capacity. Hence I asked what his charging capability is and use that to size the genset. Generators are most efficient at approximately 70% to 75% load. My own bank has a 50amp charger run off my 1kw genset
Which gives me a .3C.

Your setup will provide approx 5kw of charge when everything is perfect and all the stars are allined .
Honestly on your boat I would recommend a 4k genset.

[Allied39]

Originally Posted by

People buy a sailboat for [U

sailing[/U], not motoring, in my mind :-)

LOL!!
And sailors know that unfortunately a motor at times needs to be used, sometimes for longer periods than we wish.
I met a puritan many years back who had no motor....but was at last putting one in. The deciding factor for him was when he watched a number of boats motor away in the calm before the storm while he sat drifting waiting for the storm ......and then endured the storm while everyone else was not. I got the impression he got beat up pretty bad.
But to be honest, you seem not to be asking the question but hoping to get affirmative support.
Yeah, an excellent idea....go electric!!!!