Replace Diesel with electric engine

[Student_Driver]

https://gettozero.com/marine_overview.php

Link to the BAE Marine Systems overview Page. Note the link to brochures and schematics on the right side of the web page.

[Adelie]

SD:

Your existing motor is 50-60kW depending on configuration. Unless you have some unusual needs there’s no reason to get a 100kW genset.

If you can accept very moderate cruising speeds (3kt) under power with limited range (20nm) and generally only count on using the motor to set and retrieve the anchor, get in and out of marinas and small harbors, TE help you thru tacks in heavy air and to get you out of the way of ship that might run you down then you could go all electric charging the batteries with wind and solar and having a 2.2kW genset as the ultimate backup.

If you want the above plus the ability to to motor long distances as 5-6kt then get a 20hp parallel hybrid. Beta Marine is one supplier: https://betamarine.co.uk/he-hybrid-propulsion/ .You can do all of the above, cruising speed efficiency will be slightly better than you existing motor but you can have similar power to existing by using electric and ICE together.

If you want to motor at hull speed for any significant period, stick with the existing motor or similar. If you convert to electric drive with a genset for the prime mover you maintenance will go up and you fuel economy will go down by 15-20%.

I would suggest updating your profile with your general location and your boat make & model in the "Boat" category. This info shows up under your UserName in every post in the web view. Many questions are boat and/or location dependent and having these tidbits under your UserName saves answering those questions repeatedly. If you need help setting up your profile then click on this link: https://www.cruisersforum.com/forums...ml#post3308797

I would happily help more if the link above is not enough.

[Student_Driver]

Adelle,

Thanks for the comments. My boat is a tank and weighed in at 48,000 on the travel lift. I'd not consider less than the 75HP I currently have. When I re-power (with conventional or hybrid), I'll want the same or more power for safety. I need to power into a heavy sea and make good time under power. Currently, I can motor 7.5kts at 1800 rpm sipping fuel.

Problems are 1) Perkins needs replacement 2) I need a gen set or hybrid solution 3) I am doing a major refit (If I keep the boat, tbd) and am adding more hotel loads. Aircon, heating, water maker, clothes washer etc. I want to be able to cruise 2-4 people offshore and for distance.

[wingssail]

Originally Posted by Student_Driver

Adelle,

Thanks for the comments. My boat is a tank and weighed in at 48,000 on the travel lift. I'd not consider less than the 75HP I currently have. When I re-power (with conventional or hybrid), I'll want the same or more power for safety. I need to power into a heavy sea and make good time under power. Currently, I can motor 7.5kts at 1800 rpm sipping fuel.

Problems are 1) Perkins needs replacement 2) I need a gen set or hybrid solution 3) I am doing a major refit (If I keep the boat, tbd) and am adding more hotel loads. Aircon, heating, water maker, clothes washer etc. I want to be able to cruise 2-4 people offshore and for distance.

In my opinion you'll not only need 100kw gen set to meet the above requirements but a motor of similar capacity, plus quite a substantial battery and all the associated electronic bits.

With those requirements electric is not a suitable engineering plant for you.

There is probably no cost savings and definitely running the gen set to make the speeds and distance you think you need will not be a green solution.

Replace the diesel if you really like the boat, or consider getting one that is not such a "tank".

[Student_Driver]

I like the tank.

[wingssail]

Originally Posted by Student_Driver

I like the tank.

OK, fine. But to retain the motoring performance you desire and protect the resale value, replace or rebuild the diesel.

[Student_Driver]

I’m considering the refit because I really like how my boat handles a following/quartering sea and the low center of gravity. Am not looking to loose weight.

It’s more likely that I’ll go conventional and add a genset but I will consider the proposal.

If the genset and electric motor are similar in size/capacity, it should allow continuous use with the gen set running.

I saw the setup at the shipyard being put into commercial ferry boats around 80’. The fact that SW is using the system made me take note.

[Student_Driver]

Originally Posted by wingssail

OK, fine. But to retain the motoring performance you desire and protect the resale value, replace or rebuild the diesel.

I always thought this was the only choice. OTOH a 100kw electric drive would give plenty of power and a 100kw gen set could power it till the fuel runs dry.

This is not at all like the systems on most hybrids.


BAE builds military equipment and this system is in use in commercial vessels today.

[Adelie]

Going to diesel-electric drive will hurt you resale value, the fact that you are using a commercial system just means you will spend more money up front. When you sell it what people will see is an off brand system.
It may be a commercial system but that means that service will need to be by an authorized representative. The are fewer BAE service reps around the world than there are Betamarine and Kubota service techs.
Diesel electric is not appropriate for long distance cruising. It gives up significant fuel efficiency, like a 10-15% hit. It works well for ferries because it offers quick changes in thrust and even reversal of thrust in exchange for the lower fuel efficiency.

You need an ICE prime mover, you can’t cruise primarily on electric only. Series Diesel electric will cost you extra in fuel costs while you own it and will cost you in resale value at the end. That leaves you with either a diesel only propulsion system or a parallel hybrid system like Betamarine’s system.

[Dirk01]

@Adelie
IMHO - your totally wrong.
The fuel efficiency is 10-15% better, not worse. That's only natural.
The design point for displacement ships is around 75% of the maximum output. This also corresponds to the optimal working point of a diesel. At the same time, this also corresponds to 80% of the maximum speed.
Which cruiser lets its machine run permanently at this speed (approx. 3000 rpm) and power? I do not know anyone! Most leave their diesels between 1800 and 2100 (maybe
up to 2300 sometimes) rpm. And then use 50% less diesel at 20% less speed. For the diesel, however, it is still not the optimal operating point.
However, a variable speed hybrid system works differently. Regardless of the propeller speed, the diesel can run in the best possible speed range and thus close to the best efficiency point. This saves about 10-15% fuel.
Adelie, have you noticed that there are more and more BEVs? Worldwide! In Germany, more BEVs and hybrid systems are approved this year than pure diesel ICEs. Do you really think that in 10-15 years it will be a disadvantage to have a hybrid system?
All I know is that in 10 years I will only be able to give away an ICE car for nothing instead of selling it. That's why I bought a BEV. And yachts are developing in the same direction. However, there is still a long way to go without a diesel hybrid system. Until there will also be fuel cell technology with natural gas or even H2 here. And yachts that have already installed a maintenance-free electric drive can be converted to newer technology much more easily. That makes them more attractive on the used boat market.
But, you have to be able to think outside the box and have patience for 10-15 years.

There are many more advantages to hybridization. There are also many advantages outside of the drive system. But to explain that would go beyond the scope.
However, where I agree with the opinion of others - the intended performance of the OP are completely exaggerated. Obviously, he doesn't know the incredible thrust that an electric motor brings into the water. An electric motor from FMT Marinetechnik (Herzlich willkommen!) with Pn = 13kW (type M220) brings 2374N. At just 22kg weight! (There is now even a 25kW prototype with absolutely insane performance data.)
Just my 5 Cts...

Cheers
Dirk

[Adelie]

#$%&Dirk:
The HYMAR project the EU did in 2012 pretty conclusively determined that parallel hybrid was substantially more efficient than series. They started with the premise that series would be but learned otherwise.

There are various niches where series makes sense and is preferred, but the efficiency advantage of running the ICE prime mover at optimum RPM can not overcome the efficiency loss of converting mechanical energy to electrical, transformer, frequency controller, and electric motor which runs 8-12% for large diesel-electric marine installations.
See pg7 of http://www.trpa.org/wp-content/uploads/ABB-AS_2003.pdf.

Series electric works well in specific niches:
A. Uses where the load varies considerably over time (various work boats such as nearshore fishing vessels and coastal support vessels)
B. Uses where quick response to thrust or reversal of thrust are needed (ferries)
C. Uses where high maneuverability is needed (cruise ships using azipods which have the added benefit of using less space that could otherwise be revenue generating.)

Recreational cruise boats are most akin to offshore cargo vessels, they motor for long periods as constant speed and relatively short periods at slower speeds coming into port/marina and setting/retrieving anchor.

Part of the advantage of diesel electric in it's niches is the ability to use several prime movers and shut extra ones down when operating at lower loads. Works well in those niches, here's a discussion: http://www.interreg-danube.eu/upload...bd186ef916.pdf

The OP is not going to install multiple gensets so that he can shut 1 or more down when in a low load condition. Nor is any monohull cruising boat less than 80-100' long.

The best economy for cruising boats that want ICE prime movers is going to be parallel hybrids where the ICE is sized at or slightly above the optimum size for the owner's desired cruising speed, where electrical power from the battery can provide a 30-50% power boost for moderate periods of very high load. At lower loads when coming into a marina or anchoring the ICE can shut down and propulsion provided by battery power alone.

Parallel hybrid provides some redundancy that series does not. If the electric motor or any part of it's power system fails the ICE motor can still propell the vessel and provide some house power using the fitted alternator. For a Series system the generator will be a single point of failure, nobody is going to put in multiple gensets on a cruising boat except maybe a cat. There may or may not be duplicate drive motors and control electronics. Depends on the system.


Comparisons to land vehicles are not appropriate, most land vehicles tend to have variable loading and be used for relatively short periods of time with the ability to recharge daily from utility electrical sources, ie commuter vehicles. Ice engines will remain for the foreseeable future for specific uses but fueling them will become more specific.

[Dirk01]

Originally Posted by Adelie

#$%&Dirk:
The HYMAR project the EU did in 2012 pretty conclusively determined that parallel hybrid was substantially more efficient than series. They started with the premise that series would be but learned otherwise.

There are various niches where series makes sense and is preferred, but the efficiency advantage of running the ICE prime mover at optimum RPM can not overcome the efficiency loss of converting mechanical energy to electrical, transformer, frequency controller, and electric motor which runs 8-12% for large diesel-electric marine installations.
See pg7 of http://www.trpa.org/wp-content/uploads/ABB-AS_2003.pdf.

Series electric works well in specific niches:
A. Uses where the load varies considerably over time (various work boats such as nearshore fishing vessels and coastal support vessels)
B. Uses where quick response to thrust or reversal of thrust are needed (ferries)
C. Uses where high maneuverability is needed (cruise ships using azipods which have the added benefit of using less space that could otherwise be revenue generating.)

Recreational cruise boats are most akin to offshore cargo vessels, they motor for long periods as constant speed and relatively short periods at slower speeds coming into port/marina and setting/retrieving anchor.

Part of the advantage of diesel electric in it's niches is the ability to use several prime movers and shut extra ones down when operating at lower loads. Works well in those niches, here's a discussion: http://www.interreg-danube.eu/upload...bd186ef916.pdf

The OP is not going to install multiple gensets so that he can shut 1 or more down when in a low load condition. Nor is any monohull cruising boat less than 80-100' long.

The best economy for cruising boats that want ICE prime movers is going to be parallel hybrids where the ICE is sized at or slightly above the optimum size for the owner's desired cruising speed, where electrical power from the battery can provide a 30-50% power boost for moderate periods of very high load. At lower loads when coming into a marina or anchoring the ICE can shut down and propulsion provided by battery power alone.

Parallel hybrid provides some redundancy that series does not. If the electric motor or any part of it's power system fails the ICE motor can still propell the vessel and provide some house power using the fitted alternator. For a Series system the generator will be a single point of failure, nobody is going to put in multiple gensets on a cruising boat except maybe a cat. There may or may not be duplicate drive motors and control electronics. Depends on the system.

If I interpret the characters # $% & correctly, then the discussion is over for me.

[Adelie]

I'm Adelie, not @Adelie. This is not twitter.

"#$%&" was meant as a gentle mockery rather than swearing, though in hindsight I can see that interpretation and I apologize, I should have only used one punctuation mark with your name.

[Dirk01]

Originally Posted by Adelie

I'm Adelie, not @Adelie. This is not twitter.

"#$%&" was meant as a gentle mockery rather than swearing, though in hindsight I can see that interpretation and I apologize, I should have only used one punctuation mark with your name.

Apology accepted. That shows your honesty.
But I also have to apologize! To say that you are totally wrong - was wrong also! Because many of your arguments are correct. Even if it is your point of view and not necessarily mine.
I am actually thinking of a catamaran. And you couldn't have known that. Nevertheless, in my opinion, a single generator is sufficient even on a catamaran. Incidentally, most yachts in the 38-45ft range (often even up to 55ft) have only one engine and thus a single point of failure. And they are fine with it.
With a purely electric drive system, however, a small, portable 2kW petrol generator can be used very, very simply, to feed in the (very, very small) drive power. That should be enough for up to 2kts in calm. For larger (heavier) yachts it can of course be two generators. (And BTW, if there's wind there's no need for a drive system until you are a sailing yacht.)
So there are definitely more options ...
However, I'm talking about 2x13kW electrical power (2x18kW for short-term emergencies) and about 10kVA generator power for the long run.
I still consider the requirements outlined by the OP to be completely exaggerated. It just doesn't fit in my eyes. Unless he wants to glide into the next marina ... But that's only my 5 Cts.

Cheers
Dirk

P.S.:
Adelie, in Germany it is customary to write an @ in front of the name when others are reading a message too, to make it clear to whom the message is addressed.
So we all have our "specialties". I've heard that 2/3 of the messages are misunderstood ...

[wingssail]

I've found this boat, and the new owner (studentdriver) on Aluminum Anarchy, https://forums.sailinganarchy.com/in...minum-anarchy/

It is a beautiful and valuable boat. What it needs is some TLC, not the diesel/electric conversion he is contemplating.

Clean this boat up, get everything working, and he'll have a wonderful liveaboard and/or world cruiser.

But, install a big gen set, electric drive, and all the electrical bits to go with it, as well as removing vast amounts of what it there, unless done totally professionally will destroy the potential value of this boat. And if it is done totally professionally it will be a huge project and a huge cost.

Reconsider