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g550 · 06-11-2017, 19:05

Hello Everyone,

I own a Hunter 450 Passage with 8kw Kohler 220v AC Genset and Yanmar 4JH2 HTE engine. The engine is water damaged so I am thinking electric conversion.

The engine is 75 HP with the boat weight of 10000kg (its a 45ft boat). I think that 40-50 hp would be enough to get it to the 7-8 knots.

I also have two 90w solar panels and 8 Trojan 6v T105 225AH batteries.

What would be the best solution to repower?
Also are there controllers which can take 12v from the batteries as well as 220v AC from the genset to create a hybrid propulsion?

Thank you.

Jman · 06-11-2017, 19:37

Do some searches. There was even a pretty long thread recently. Short answer is no.

44'cruisingcat · 06-11-2017, 19:57

40 HP is about 30 kW. So you need to be able to produce 30 kW continuously. Your genset and solar don't.

g550 · 06-11-2017, 20:33

Ok, I have to add more info.

1. I am located in Hong Kong. It is very difficult to replace the engine here. It is very expensive and majority of mechanics are not reliable.

2. The boat will be used for coastal sailing. So most of the time the engine will be running only to get to my mooring and out. This is about 5 mins at 10% power or so.

3. I understand that 40hp diesel engine is about 20hp electric engine bcz of alternator, pumps etc loads. Please correct me if I am wrong.

4. 8kw coming out of my genset will give me 6-7 knots in calm conditions.

akprb · 07-11-2017, 08:06

Will kill the re-sale.

Reporter with a Yanmar, maybe even go up a horsepower.

Will improve resale, simple, fast and smart.

sailorboy1 · 07-11-2017, 08:16

get a new engine

Kenomac · 07-11-2017, 08:17

We previously owned a Hunter 450 passage; your plan is foolish. You'll be extremely lucky to even be able to power out of your marina under electric. The boat has such a high freeboard, any wind at all will overpower an electric motor.

You'd be better off attaching a 20-25hp outboard or installing a new diesel.

**a64pilot** · 07-11-2017, 08:19

Get another boat to tow you, honestly.
The electric just isn’t realistic, the levels of electrical power required are orders of magnitude of what you think they are.

**skipmac** · 07-11-2017, 09:15

Hi G550,

I have a fairly heavy 42' boat and for various reasons (including the fact that I am an electrical engineer) I would like to repower with electric but based on a lot of research it isn't practical or economical.

Comments below.

QUOTE=g550;2513961]Ok, I have to add more info.

1. I am located in Hong Kong. It is very difficult to replace the engine here. It is very expensive and majority of mechanics are not reliable.

If it's difficult to find good work on a standard boat engine it will be even more difficult and expensive to install a non standard system like electric.

2. The boat will be used for coastal sailing. So most of the time the engine will be running only to get to my mooring and out. This is about 5 mins at 10% power or so.

This will solve the biggest problem of cruising range under power. The generator will help but 8 kW will be barely enough to cruise in very calm conditions. Strong winds or currents you will slow to a crawl.

3. I understand that 40hp diesel engine is about 20hp electric engine bcz of alternator, pumps etc loads. Please correct me if I am wrong.

My opinion that is over optimistic. On an engine that size parasitic loads I think would be on the order of 5-10 hp tops. Also,
I don't recommend going short on the HP even if the plan is just for coastal and getting in/out of dock and harbor. I have found the times I have needed the most HP was maneuvering in tight quarters around the harbor.

4. 8kw coming out of my genset will give me 6-7 knots in calm conditions.

This I would say is about right.
[/QUOTE]

Other comments. There are very few if any ready to go marine electric systems that will come close to 40-50 HP. Even smaller motors I've found are as much or more than a new diesel, especially after you add the cost of controllers and such. You could go for an industrial electric motor but then you will be doing a custom job and either have to be very technical or pay an engineer for a custom install and again, there goes the savings.

Cadence · 07-11-2017, 09:50

Quote:

Originally Posted by g550

Ok, I have to add more info.

1. I am located in Hong Kong. It is very difficult to replace the engine here. It is very expensive and majority of mechanics are not reliable.

2. The boat will be used for coastal sailing. So most of the time the engine will be running only to get to my mooring and out. This is about 5 mins at 10% power or so.

3. I understand that 40hp diesel engine is about 20hp electric engine bcz of alternator, pumps etc loads. Please correct me if I am wrong.

4. 8kw coming out of my genset will give me 6-7 knots in calm conditions.

Diesel electric is generally for control and is DC with s significant power loss. Great for things like ferries that make short runs and controlled crashes into a slip.

dperchlik · 07-11-2017, 10:51

My first Electric boat was a Coronado 35. I refit with a 10kW DC motor and six 6V batteries in series. No solar panels and no generator. I sailed the boat for 4yrs in the PNW and was able to sell it for what I paid. I used the electric motor to get in and out of the marina. Yes there was the time it took me 15hrs to sail from Tacoma to Seattle, but I would rather sail then motor. It made me a better sailor and I learned to sail into and off the dock. Sure, there were times when there was no wind and I really wanted to get somewhere, that is the price you pay. Without the motor you plan ahead and I never felt that my safety was compromised. Sure if I had a big diesel motor I may have motored into the marina at full running of the tide and a nice cross wind but with my "underpowered" electric motor I would enjoy a few more hours sailing till the wind shifted and the current was manageable.

dperchlik · 07-11-2017, 11:28

My 2nd Electric Boat is a Formosa 47 with an Electric Yacht, QuietTorque™ 20.0 – 20kW, 48v, system with a Kobota Marine diesel 48V 20kW DC generator from Ample Power Company. I did the install myself.
I leave and return to the dock or anchor under electric power. It is nice not having to talk over the diesel engine. Nice to have the diesel generator even though I don't use if very often.

*Is it practical - for me yes

*Can I motor all day if I want - yes, but never have

*Was it more expensive than just replacing the dead 90hp Ford Lehman - Yes if you just count parts.

*Did I kill the resale value - much easier to sell a boat with a working electric motor than an non-working diesel motor. I didn't have any problem selling my last electric only boat, will find out if I ever put her up for sale.

*What I like -
1. not having to power up the diesel to leave the dock
2. Being able to go under power at the push of a handle
3. quite motor sailing, I can even hear prop cavitation and know to back off the throttle.
4. Smaller diesel engine has less noise than my old 90hp
5.I can run the electric motor at very low RPM, which has been helpful in tight docking situations
6. System takes less space in the engine compartment making it easier to get in there and do the minimal maintenance required.

*What I don't like-
1. I still have a diesel motor
2. I have to spend more time monitoring battery state of charge and water level.

hamburking · 07-11-2017, 11:42

Quote:

Originally Posted by akprb

Will kill the re-sale.

Reporter with a Yanmar, maybe even go up a horsepower.

Will improve resale, simple, fast and smart.

I have to disagree. I believe diesel electric is the future of auxiliary power. I would definitely buy his electric powered boat over a conventional yanmar...and I hope to find one to buy when my turn comes around.

I understand the benefits of conventional diesel power. And I understand the limitations of electric. For the PO it sounds like a GREAT solution.

There will always be resistance to change. Get the electric motor...you will love the calm and quiet coming into a dock/anchorage under battery power.

Cadence · 07-11-2017, 12:35

Quote:

Originally Posted by dperchlik

My 2nd Electric Boat is a Formosa 47 with an Electric Yacht, QuietTorque™ 20.0 – 20kW, 48v, system with a Kobota Marine diesel 48V 20kW DC generator from Ample Power Company. I did the install myself.
I leave and return to the dock or anchor under electric power. It is nice not having to talk over the diesel engine. Nice to have the diesel generator even though I don't use if very often.

*Is it practical - for me yes

*Can I motor all day if I want - yes, but never have

*Was it more expensive than just replacing the dead 90hp Ford Lehman - Yes if you just count parts.

*Did I kill the resale value - much easier to sell a boat with a working electric motor than an non-working diesel motor. I didn't have any problem selling my last electric only boat, will find out if I ever put her up for sale.

*What I like -
1. not having to power up the diesel to leave the dock
2. Being able to go under power at the push of a handle
3. quite motor sailing, I can even hear prop cavitation and know to back off the throttle.
4. Smaller diesel engine has less noise than my old 90hp
5.I can run the electric motor at very low RPM, which has been helpful in tight docking situations
6. System takes less space in the engine compartment making it easier to get in there and do the minimal maintenance required.

*What I don't like-
1. I still have a diesel motor
2. I have to spend more time monitoring battery state of charge and water level.

A very honest assessment thanks. I doubt I'd want the complexitt but some may.