Electric Propulsion on Catamarans

[yamez4u]

Originally Posted by StuM

>
Congratulations. That is even more irrelevant to the topic than the Russian missile boat engines.

More relevant then a guy talking about diesels on a thread about electric boats. And yet still no link on any petro engine with a MTBF above 10000 hours? Which is pretty run of the mill for any electric traction motor.

[BigBeakie]

Deckofficer,

Could you explain what you mean by chokes and other design issues that should be considered?

Induced current/back EMF is a strange effect. How do you calculate what cable length or length difference between 2 cables will cause the problem?

[nimblemotors]

I would put the motor controller right at/in the motor so it gets water cooled along with the motor.

You most definitely don't want to have a really long cable from controller to motor.

[yamez4u]

Originally Posted by 44'cruisingcat

If you knew anything about my past or my boat you know how absolutely stupid that post is. The abbreviation NFI could have been created just for you.

What's to know you keep say absolutely stupid things. The number one item on any boat that could break and does break is a petro engine, maybe followed by head system failures. Saying a petro engine is more reliable then an industrial electric traction motor it plain absurd, the fact you brought it up on a forum talking about an unrelated topic makes it even worse.

But beside say over and over if I only knew you.....instead backup your crazy talk with some comparative studies on MTBF of diesel versus industrial electric motors. A tiny bit of understanding of how much more reliable large electric motors are compared to your typical diesel should speak for itself.

There is a reason so much of the industry is installing electric hybrid systems. Reason number one is reliability. Followed closely by cost savings.

[handmer]

I have no experience with Torqeedo motors in person, but from what I have seen online the motor is mounted in the pod below the water.

In the electric trolling motors I have, the metal casing provides an excellent heat sink in the water. If the Torqeedo motors are designed so that despite the massive heat sinking available in the water, the motors can overheat, then that is a very big design flaw.

The idea that the mounting bracket is needed for motor cooling is very odd to me. Why use a part that could be in the sun and is far from the motor to cool a motor that is under the water? I think there must be a lot more to this story.

It seems more plausible that the bracket is used as a heat sink for the controller, but I don't know enough about the design. Maybe they are built with flaws. Maybe they were modified in ways that created problems.


From what I read of the boat though, the numbers on the hybrid solar electric system stacked up and the concept worked. The problem was an incorrect choice of motors (be it from a no user fault quality point of view or for suitability for the use) and/or incorrect modifications and mounting setup for the application. Of course it would be nice if there was the exact spec product to do what you need (or what a company says it will do) but in a fairly new field there will be always be some experimentation needed. It is just one of the factors to take into consideration when considering electric or not.

[yamez4u]

Originally Posted by BigBeakie

Induced current/back EMF is a strange effect. How do you calculate what cable length or length difference between 2 cables will cause the problem?

A good wire size calculator can save you a ton of grief later. Remember the positive and nagitive cables added together are a single path. Unless the table says otherwise. The two tables below might save you some time. If you are really worried about EMF and induced current they make shielded cables. But another strategy to help with that is to keep the cables the same length and twist them around each other.


Voltage Drop Calculator Genuinedealz.com
American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies and wire breaking strength

[yamez4u]

Originally Posted by nimblemotors

You most definitely don't want to have a really long cable from controller to motor.

Total agree with this statement. The cables from my controllers to my motors is 2 foot 1/0 cable. And I may replace them with 2/0 cable.

[BigBeakie]

Ok , my last post on the Torqeedo issue, I promise.

Look, I've got no dog in this hunt, other than I am CONSIDERING using a Torqeedo motor in a cruising cat and that is the basis of my questions. And I am no expert on electric motors, for sure.

BUT, when someone on the Internet rubbishes a vendor with sweeping statements about reliability (from a single incident) and then another cites an example with multiple motor replacements and clearly implies the product is at fault, then I thought it was worthwhile commenting.

For clarity, of course Torqeedo have overheating protection. Check your facts before making silly statements. They show over spec heating on the display with flashing lights, they have temp sensing and motor shutoff in high overheating situations. And BTW I never said the motor failed because of overheating, it apparently did not. Units failed because of the back EMF induced current in cable between the battery and motor & leaking prop shaft seal.

It is disingenuous of you 44'cruising cat to say the problems continued after the battery was moved closer to the motor. That fixed the EMF issue, and then there was the propshaft incident, a totally different cause of failure. But you want to grind that ax, so I now understand your lack of objectivity.

I am aware of several cats using cruise 4 motors for several years and have heard good news about all of them, and I have checked on Torqeedo's bona fides re quality and ongoing R&D and quality improvement, so I will judge accordingly between those facts and the opinions of individuals on a forum who obviously seem less than objective.

Over and out

[deckofficer]

Originally Posted by BigBeakie

Deckofficer,

Could you explain what you mean by chokes and other design issues that should be considered?

Induced current/back EMF is a strange effect. How do you calculate what cable length or length difference between 2 cables will cause the problem?

That is just it, we the end users shouldn't have to improve on their engineering to work. A choke will take out unwanted RF and a flywheel diode will keep back EMF coming from the motor into the controller.

[handmer]

Originally Posted by BigBeakie

And BTW I never said the motor failed because of overheating

I have nothing for or against Torqeedo, but BigBeakie you did say the motors overheated. You did not say that the motors failed due to overheating, but then again no one has accused you of saying that from I have seen.

Originally Posted by BigBeakie

he altered the design engineering principals of the product and that caused the motors to (1) overheat

So was it the motors that overheated or not? If so, can you shed light on why the case and brackets would be used to cool the underwater motor?

[BigBeakie]

Yes, that was me not being specific, sorry about that. I was using the term motor in the sense of the whole unit.

To be specific, as I understand it the controller is up in the casing, and you are correct the motor is cooled by water conduction, so it was not the motor that overheated, but the controller.

The owner removed the casing and thus removed the controller cooling.

The whole unit can withstand overheating and continue to operate, up to a point of course. There are warning lights and override/shutdown protection so the motor isn't cooked. When it cools down, it still runs.

By the way, the engineering sophistication of the Deep Blue system is very interesting indeed, and part of the reason I'm interested in it. Every Deep Blue installation, anywhere in the world, is carried out by a certified Torqeedo engineer, so DIY types like boat alexandra and 44'cruisincat's mate can't screw it up.

I would encourage anyone who has any questions, doubts, or needs clarification about anything to make a phone call to...Torqeedo. They know what they are talking about. I do not, on a technical level.

[handmer]

Fair enough, that is a different story then.

In the end it seemed that while there were issues, the concept behind the hybrid solar electric with generator cruising worked on that scale.

[44'cruisingcat]

[QUOTE=yamez4u;1586101]What's to know you keep say absolutely stupid things. The number one item on any boat that could break and does break is a petro engine, maybe followed by head system failures. Saying a petro engine is more reliable then an industrial electric traction motor it plain absurd, the fact you brought it up on a forum talking about an unrelated topic makes it even worse.

[QUOTE]

Can you show me where I have said anything you claim I've said?
That diesels are more reliable than industrial electric motors.

Fact is, I have NOT said that at all.

So go on, show me where I have.

Talk about crazy statements...

[44'cruisingcat]

Originally Posted by BigBeakie

Ok , my last post on the Torqeedo issue, I promise.

It is disingenuous of you 44'cruising cat to say the problems continued after the battery was moved closer to the motor. That fixed the EMF issue, and then there was the propshaft incident, a totally different cause of failure. But you want to grind that ax, so I now understand your lack of objectivity.


Over and out

No, it was a statement of FACT. There were FIVE failures of the Torqeedos. You seem to have been given the impression there were three.

I have no axe to grind. I've never owned a Torqeedo, and I'm not likely to,
so it's no problem to me.

In fact I'll even encourage you to go ahead with them. Go for it.

[nimblemotors]

You know we go around in circles all the time on these kind of subjects.

Schools Out had quite a cool setup, being innovative and trying new things, unfortunately early adopters often find themselves in rough seas.
The electric pods were simply too small for that size boat in my opinion.
Not much penalty to have motors a little bigger than one might possibly get away with, particularly for a larger boat when 20 lbs means nothing.
On a dinghy 20 lbs might matter.

By the way, '44' did an impressive job putting in the outboards when repairing that boat.