Hello everyone,
imagine a modern version of the classiest coronet models.
Preserving the timeless design and charm by providing modern technology inside, powered by powerful electric engines.

Which features and characteristics should such a boat bring on board?

We are thankful for any input.

best regards
JP

When i am bored i sometimes try to calculate the weight and range of my 32 OF if put in electrical motors instead.

I have 2 VP ad41p that have a (dry) weight of approx 538 kg. (including outdrives) That happens to also be the weight of a Tesla 85kwh battery.

So if i replace my engines with two 85 kwh tesla batteries, keep the outdrives and add some electric motors i would get approximately the same weight as my boat currently has when i have 600 liters of diesel on board.

At full throttle my VPs give 147 kw each.
When run on electric power the batteries would be able to sustain that power output for approx 35 minutes.
When i go full throttle my boat makes about 33 knots. giving the electric version of my of32 a range of approx 19 nm.

Not super impressive..... (especially since i just spent maybe 3 Msek on rebuilding the boat)

The diesel configuration gives a range of about 220 nm.

at lower speeds range would be much better (both for electric and diesel propulsion)

And of course if someone would actually do this they would convert into a single drive setup. That could give more efficiency - maybe 40 % longer range at top speed :-)

Still not very impressive

My conclusion is that unfortunately Coronet boats are not well suited for electric propulsion - they simply require to much power to drive. An electric boat needs to be light and narrow (like a canoe or a sailboat) or use some esoteric technology like hydrofoils....

I love the idea of a modern electric Coronet. Göstas findings based on his current boat seems fully correct and refitting his vessel with electric propulsion is probably out of the question. Both with regards to cost and performance. Doing a full redesign, using all state of the art findings around hull, weight, electric motors, driveline, battery technology, charging and why not, as Gösta suggests, hydrofoils(!) is a super-interesting project. The technology challenge is big but feasible, I''d say, and the idea of letting the classic Coronet charm be the driver from a design point of view is marvellous. I am a lucky new owner of a Coronet DC21 with Mercruiser 4,3 L , 220 hk, 2001 engine and I have already started to figure out how a future plug-in hybrid solution would give this 1968 boat another 50 years to live. So my kids and grandchildren can still enjoy the classic boat. Going in and out of harbours and also short swim- and fishing trips electrically and then longer ones on bio-fuel is a vision that I''d love to let come through. If I ever do this or not, I don''t know, but it would certainly be a good step on the learning curve of builing the E-Coronet! Some time ago before I decided to buy a motorboat I was thinking about a camper and since I am an electrical engineer I immediately started to juggle ideas around the "impossible " idea of a full-electric camper. I got excited and started a blog in order to maintain ideas around that and see how feasible it would be to get a full e-camper in place for 2022. The blog is still alive (with no visitors!) but is on hold since I now have a Coronet and no longer dream of campers. Reading your post left me inspired to pivot it into an E-Coronet blog instead. I''m in your project, for sure! My on-hold-blog (in swedish) is here https://andershusbilsblogg.blogspot.com and in the oktober-november posts of 2017 I made the maths around "My E-Camper". Same thing can of course be done on the E-Coronet. Send me a mail and we''ll do the outlining together! Again, I love the idea!

Fnm marine have a hybrid engine maybe that is what you are looking for regards hans

Since all electric charging directly or indirectly will have to be done with fossile fuel, all electric enginges will be less environmental sustainable than petrol och diesel ones. The electric enginge in itself is far more efficient, but energy losses in power plants and in transportation of the energy, will probably make it less efficient in all. And then production and destruction of all the batteries will make the total "footprint" far bigger.

Steyr has hybrid electric diesel engines that would work for a coronet.

http://www.steyr-motors.com/fileadmin%2Ffiles%2FDownloadCenter%2Fmanuals___spare_parts%2FBrochures%2FGeneral%2FMarine_STEYR-HDS_digital.pdf

They deliver max 20 kw on electric though so no planning speeds on electric.....

Here is another supplier that seems semi able to deliver a hybrid drivetrain: http://www.amperetta.com/

and another:
https://betamarine.co.uk/portfolio-item/he-hybrid-propulsion/

and another:
http://www.hybrid-marine.co.uk/5.html

i think this guy had a nice solution to retrofitting electric propulsion in addition to a diesel engine:
https://www.youtube.com/watch?v=wEqWjv-8I0U

Times are changing. Now there are actually engines that could work end even battery capacity (if you combine it with a small gas or diesel driven emergency charger). The issue now is more the cost so we might have to wait another 5 years maybe before conversation is a thing for real even for old heavy coronets