Considering Electric Outboard - Advice ?

[44'cruisingcat]

Originally Posted by Eric ROGUE

If anyone has any information about real world performance of Torqeedo outboards in comparison with the gas outboard that had been propelling a particular sailboat, I sure would like to hear it. I talked to a dealer who used (I believe) an 801 mounted on a 19' full keel sailboat along the coast of Maine. It handled waves and current "like a six hp gas outboard". That motor was a beautiful design. LONG shaft. Can be tilted up. Can also slide up the length of the shaft.

A friend of mine fitted a pair of Torqueedos to his 44 foot cat, along with the 48 volt battery and generator required to power it. Torqueedo actually used video of his boat as part of their promotion.

Performance was probably just a little less than a pair of 9.9 hp outbards. Adequate, but not more.

What he did like was being able, on occassion, to leave a marina and get sailing without the genset having started.

However, the motors did not prove to be reliable, with frequent failures of the speed controllers, corrosion, water entry, a gearbox failure etc. etc..

IIRC he replaced 5 or maybe 6 motors in about 6 months. All done without hesitation under warranty. (Except one time when he had to wait a month or so for a replacement motor)

He also believes that a speed controller failure caused damage to his generator system on one occassion.

Finally the lack of reliability became too much, and he fitted an outboard, and has asked for a refund.
He also asked that they stop using video of his boat to promote themselves.

[FrankZ]

Originally Posted by 44'cruisingcat

A friend of mine fitted a pair of Torqueedos to his 44 foot cat, along with the 48 volt battery and generator required to power it. Torqueedo actually used video of his boat as part of their promotion.

I saw a video of a small boat using the Torqueedo and what struck me how insanely loud it was. Did you friend have issues with noise as well?

[Eric ROGUE]

Thank you for the very informative post.

Thank you for saving me a lot of stress. That settles the question about Torqueedo. I was already concerned that they are overly expensive, but unreliable as well is completely unacceptable. What if your friend had not used his Torqueedos enough to discover their flaws while still under warranty? That would have been a real disaster.

Diesel-electric drives are common on large ferries and other large vessels. Seems like the advantages could be well used on sailboats at no greater expense than all mechanical drives. The flexibility of installation seems compelling. And how nice to leave the marina quietly on battery power and return as well, but to be able to use the engine until the diesel runs out if desired. Save wear and tear on the diesel as well. DC motors can have very high torque low speed to swing a very large prop spinning at maximum efficiency for sailboat speeds hidden by the at the aft end of a rudder, keel or skeg in front of a rudder (motor mounted in the rudder, keel, or skeg), or lowered on a shaft into the water only when needed.

I can dream can't I.

At any rate a sailor on another forum who has used electric propulsion for many years ( writes, "The Torquesdo is silly expensive and it's high price is more related to a glitzy
advertising campaign rather than the tech that goes into it. If you want to buy
a production electric propulsion system talk to Scott at Electric Yacht
(http://www.electricyacht.com)"

I'm skiing. I'll pursue propulsion options in the spring or stick with my current outboard powered tug propulsion (inflatable).

[Adelie]

Originally Posted by Eric ROGUE

Diesel-electric drives are common on large ferries and other large vessels. Seems like the advantages could be well used on sailboats at no greater expense than all mechanical drives. The flexibility of installation seems compelling. And how nice to leave the marina quietly on battery power and return as well, but to be able to use the engine until the diesel runs out if desired. Save wear and tear on the diesel as well. DC motors can have very high torque low speed to swing a very large prop spinning at maximum efficiency for sailboat speeds hidden by the at the aft end of a rudder, keel or skeg in front of a rudder (motor mounted in the rudder, keel, or skeg), or lowered on a shaft into the water only when needed.

I can dream can't I.

Diesel electric works on medium-large ferries despite it's large power loss of 20-30% because it can respond very quickly changing thrust levels or even reversing thrust and because This is neccessary for quick turnaround times at ferry landings. On very large motor vessels, reverse is obtained by stopping the motor and restarting it spinning backwards, there is no reverse gear. At cruising speeds mechanical drives have a 3-10% power loss.

Also ferry runs are typically shorter than normal frieght or passenger vessels so the ferry's engines aren't operating at optimum RPM's for very long so the efficiency advantage of mechanical drive does not have as long to kick in, the better turn around times make up for the efficiency advantage.

For a cruiser the efficiency of a mechanical drive is the way to go.

Sorry to rain on your nice idea, I've had it to.

Personally I intend to add a small trolling motor on a outboard bracket to the next boat so I can ghost out of marinas on battery power.

Optimally someone would design an electric motor that piggy backs onto the prop shaft between the transmission and the packing gland. That way the boat can be ghosted on battery or solar power, or it can generate power when the wind is up and the boat is moving along well under sails.

[beau]

Buy a 2 or 4 stroke outboard motor.

This whole Solar, electric motors stuff is a load of BS.
Batteries ar not advanced enough to be efficient and the power "rating" of Solar panels is also BS.
It is all a big con getting at you green's and do gooders to "do the right thing"

[Eric ROGUE]

Good points Adelie. Good reminders. In my enthusiasm I had forgotten how efficient some mechanical drives can be made to be, and how inefficient it is to convert energy from one form to another.

There are lots of efficiencies: total cost of operation per thrust, weight vs thrust, size vs thrust, etc.. Low maintenance costs and high torque of DC motors are distinct advantages. Total cost of operations are not always immediately obvious in a system such as the propulsion and electrical generation systems of a boat, and are worth considering.

I don't use an engine much and would usually only need docking power. 110 amps at 48v would propel me at hull speed for over an hour, and a couple of hours at reduced speed. A DC motor that can also be a generator when the prop is dragged through the water would allow recharging any time the wind is blowing enough for the drag not to matter. Batteries and Diesel or gas generator could be located anywhere convenient, or helpful to stability. They would not have to occupy some of the best part of the vessel inboard installations often do, nor the other frequent option of being crammed into a maintenance nightmare box.

As for do-gooder solar nuts... During the 1970s oil crisis there was lots of discussion about oil, how much left, etc., etc.. I did a calculation based upon the rate of growth of energy consumption since the discovery of oil to 1970, and projecting that growth rate out to infinity assuming that every particle of earth could be converted to energy as efficiently as oil can be in order to answer the question, how long before every particle of earth would be gone. Answer: approximately 500 years. The world has to move from fossil fuels to renewable forms of energy and the sooner the world does so the more freedom of the seas us cruisers will continue to enjoy, and the less chaos, death, and destruction there will be (Oil grows food. Nations exist or fail based on whether they can feed their people or not. We've seen the problems created by just a couple of failed states.)

I can only justify the continued use of my ecologically horrible 2 cycle outboard because it gets very little use and I spill more oil changing the oil in my car than pours through its exhaust. Given current reality I will probably replace it with a 4 cycle outboard, because a feasible electric option is not immediately obvious. But until I do buy a new outboard, I am not done exploring the possibility of electric drive. For those needing to replace an inboard drive there apparently are viable cost and performance options (see the link in my prior post).